[RFC PATCH] powerpc/ftrace: Refactoring and support for -fpatchable-function-entry
Naveen N Rao
naveen at kernel.org
Sat May 20 05:26:00 AEST 2023
Refactor ftrace code and move to using ftrace_replace_code() to help
simplify and make the code more maintainable.
- The existing ftrace.c code is moved to a separate file so that ppc64
elfv1 and clang -pg only support continue. This makes it possible to
converge ppc32 and ppc64 support further.
- Drop code to re-purpose compiler-generated long branches for ftrace
use in support of large kernels. We still retain the ftrace stubs at
the end of .text, so we now support kernels upto ~64MB.
- Add ftrace_init_nop() to keep boot-time validations and init separate
from runtime.
- Implement ftrace_replace_code() to simplify overall ftrace setup. This
will be especially useful when adding ability to nop out 'mflr r0'
later, and for other subsequent ftrace features.
- Add support for -fpatchable-function-entry. On ppc64, this needs gcc
v13.1 so that the nops are generated at LEP. This also moves ppc32 to
using the same two-instruction sequence as that of ppc64.
This applies atop patches 1-3 of Nick's series for elfv2 conversion, as
well as Nick's patch enabling -mprofile-kernel for elfv2 BE:
- https://lore.kernel.org/all/20230505071850.228734-1-npiggin@gmail.com/
- https://lore.kernel.org/all/20230506011814.8766-1-npiggin@gmail.com/
This builds for me and passes a quick test, posting this as an early
RFC.
Signed-off-by: Naveen N Rao <naveen at kernel.org>
---
arch/powerpc/Kconfig | 10 +
arch/powerpc/Makefile | 5 +
arch/powerpc/include/asm/ftrace.h | 10 +-
arch/powerpc/include/asm/module.h | 4 -
arch/powerpc/kernel/trace/Makefile | 8 +-
arch/powerpc/kernel/trace/ftrace.c | 816 +++++------------
arch/powerpc/kernel/trace/ftrace_pg.c | 846 ++++++++++++++++++
.../gcc-check-fpatchable-function-entry.sh | 20 +
8 files changed, 1106 insertions(+), 613 deletions(-)
create mode 100644 arch/powerpc/kernel/trace/ftrace_pg.c
create mode 100755 arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 902b6b99f7ecd5..6db94723af7d30 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -187,6 +187,7 @@ config PPC
select DYNAMIC_FTRACE if FUNCTION_TRACER
select EDAC_ATOMIC_SCRUB
select EDAC_SUPPORT
+ select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY if ARCH_USING_PATCHABLE_FUNCTION_ENTRY
select GENERIC_ATOMIC64 if PPC32
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_CMOS_UPDATE
@@ -552,6 +553,15 @@ config MPROFILE_KERNEL
def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN
def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN
+config ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP
+ depends on PPC64_ELF_ABI_V2 && FUNCTION_TRACER
+ def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mlittle-endian) if CPU_LITTLE_ENDIAN
+ def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh $(CC) -mbig-endian) if CPU_BIG_ENDIAN
+
+config ARCH_USING_PATCHABLE_FUNCTION_ENTRY
+ depends on FUNCTION_TRACER && (PPC32 || PPC64_ELF_ABI_V2)
+ def_bool ARCH_HAS_PATCHABLE_FUNCTION_ENTRY_AT_LEP || (PPC32 && $(cc-option, -fpatchable-function-entry=2))
+
config HOTPLUG_CPU
bool "Support for enabling/disabling CPUs"
depends on SMP && (PPC_PSERIES || \
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index dca73f673d7046..de39478b1c9e9f 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -148,11 +148,16 @@ CFLAGS-$(CONFIG_PPC32) += $(call cc-option, $(MULTIPLEWORD))
CFLAGS-$(CONFIG_PPC32) += $(call cc-option,-mno-readonly-in-sdata)
ifdef CONFIG_FUNCTION_TRACER
+ifdef CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY
+KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
+CC_FLAGS_FTRACE := -fpatchable-function-entry=2
+else
CC_FLAGS_FTRACE := -pg
ifdef CONFIG_MPROFILE_KERNEL
CC_FLAGS_FTRACE += -mprofile-kernel
endif
endif
+endif
CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 91c049d51d0e10..d1a16543a37b00 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -22,18 +22,26 @@ extern void _mcount(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
- /* relocation of mcount call site is the same as the address */
+ if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY))
+ addr += MCOUNT_INSN_SIZE;
+
return addr;
}
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
unsigned long sp);
+struct module;
+struct dyn_ftrace;
struct dyn_arch_ftrace {
struct module *mod;
};
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
+#define ftrace_need_init_nop() (true)
+int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
+#define ftrace_init_nop ftrace_init_nop
+
struct ftrace_regs {
struct pt_regs regs;
};
diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index ac53606c259430..a8e2e8339fb7f4 100644
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -75,10 +75,6 @@ struct mod_arch_specific {
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
-# ifdef MODULE
- asm(".section .ftrace.tramp,\"ax\", at nobits; .align 3; .previous");
-# endif /* MODULE */
-
int module_trampoline_target(struct module *mod, unsigned long trampoline,
unsigned long *target);
int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs);
diff --git a/arch/powerpc/kernel/trace/Makefile b/arch/powerpc/kernel/trace/Makefile
index b16a9f9c0b35f2..2296bbbd775ac8 100644
--- a/arch/powerpc/kernel/trace/Makefile
+++ b/arch/powerpc/kernel/trace/Makefile
@@ -8,13 +8,13 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
endif
-obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o
+obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o
ifdef CONFIG_MPROFILE_KERNEL
-obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o
+obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_mprofile.o ftrace.o
else
-obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o
+obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64_pg.o ftrace_pg.o
endif
-obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o ftrace.o
+obj-$(CONFIG_FUNCTION_TRACER) += ftrace_low.o
obj-$(CONFIG_TRACING) += trace_clock.o
obj-$(CONFIG_PPC64) += $(obj64-y)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index a47f303734233b..a9d57f338bd78e 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -28,64 +28,52 @@
#include <asm/syscall.h>
#include <asm/inst.h>
-/*
- * We generally only have a single long_branch tramp and at most 2 or 3 plt
- * tramps generated. But, we don't use the plt tramps currently. We also allot
- * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
- * tramps in total. Set aside 8 just to be sure.
- */
-#define NUM_FTRACE_TRAMPS 8
+#define NUM_FTRACE_TRAMPS 2
static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
-static ppc_inst_t
-ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
+static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
{
ppc_inst_t op;
- addr = ppc_function_entry((void *)addr);
-
- /* if (link) set op to 'bl' else 'b' */
+ WARN_ON(!is_offset_in_branch_range(addr - ip));
create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
return op;
}
-static inline int
-ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
+static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
{
- ppc_inst_t replaced;
-
- /*
- * Note:
- * We are paranoid about modifying text, as if a bug was to happen, it
- * could cause us to read or write to someplace that could cause harm.
- * Carefully read and modify the code with probe_kernel_*(), and make
- * sure what we read is what we expected it to be before modifying it.
- */
-
- /* read the text we want to modify */
- if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
+ if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
+ pr_err("0x%lx: fetching instruction failed\n", ip);
return -EFAULT;
-
- /* Make sure it is what we expect it to be */
- if (!ppc_inst_equal(replaced, old)) {
- pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
- ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
- return -EINVAL;
}
- /* replace the text with the new text */
- return patch_instruction((u32 *)ip, new);
+ return 0;
}
-/*
- * Helper functions that are the same for both PPC64 and PPC32.
- */
-static int test_24bit_addr(unsigned long ip, unsigned long addr)
+static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
{
- addr = ppc_function_entry((void *)addr);
+ ppc_inst_t op;
+ int ret;
- return is_offset_in_branch_range(addr - ip);
+ ret = ftrace_read_inst(ip, &op);
+ if (!ret && !ppc_inst_equal(op, inst)) {
+ pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
+ ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
+{
+ int ret = ftrace_validate_inst(ip, old);
+
+ if (!ret)
+ ret = patch_instruction((u32 *)ip, new);
+
+ return ret;
}
static int is_bl_op(ppc_inst_t op)
@@ -93,138 +81,11 @@ static int is_bl_op(ppc_inst_t op)
return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
}
-static int is_b_op(ppc_inst_t op)
-{
- return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
-}
-
-static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
-{
- int offset;
-
- offset = PPC_LI(ppc_inst_val(op));
- /* make it signed */
- if (offset & 0x02000000)
- offset |= 0xfe000000;
-
- return ip + (long)offset;
-}
-
-#ifdef CONFIG_MODULES
-static int
-__ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long entry, ptr, tramp;
- unsigned long ip = rec->ip;
- ppc_inst_t op, pop;
-
- /* read where this goes */
- if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
- pr_err("Fetching opcode failed.\n");
- return -EFAULT;
- }
-
- /* Make sure that this is still a 24bit jump */
- if (!is_bl_op(op)) {
- pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
- return -EINVAL;
- }
-
- /* lets find where the pointer goes */
- tramp = find_bl_target(ip, op);
-
- pr_devel("ip:%lx jumps to %lx", ip, tramp);
-
- if (module_trampoline_target(mod, tramp, &ptr)) {
- pr_err("Failed to get trampoline target\n");
- return -EFAULT;
- }
-
- pr_devel("trampoline target %lx", ptr);
-
- entry = ppc_global_function_entry((void *)addr);
- /* This should match what was called */
- if (ptr != entry) {
- pr_err("addr %lx does not match expected %lx\n", ptr, entry);
- return -EINVAL;
- }
-
- if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
- if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
- pr_err("Fetching instruction at %lx failed.\n", ip - 4);
- return -EFAULT;
- }
-
- /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
- if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
- !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
- pr_err("Unexpected instruction %08lx around bl _mcount\n",
- ppc_inst_as_ulong(op));
- return -EINVAL;
- }
- } else if (IS_ENABLED(CONFIG_PPC64)) {
- /*
- * Check what is in the next instruction. We can see ld r2,40(r1), but
- * on first pass after boot we will see mflr r0.
- */
- if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
- pr_err("Fetching op failed.\n");
- return -EFAULT;
- }
-
- if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
- pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
- ppc_inst_as_ulong(op));
- return -EINVAL;
- }
- }
-
- /*
- * When using -mprofile-kernel or PPC32 there is no load to jump over.
- *
- * Otherwise our original call site looks like:
- *
- * bl <tramp>
- * ld r2,XX(r1)
- *
- * Milton Miller pointed out that we can not simply nop the branch.
- * If a task was preempted when calling a trace function, the nops
- * will remove the way to restore the TOC in r2 and the r2 TOC will
- * get corrupted.
- *
- * Use a b +8 to jump over the load.
- * XXX: could make PCREL depend on MPROFILE_KERNEL
- * XXX: check PCREL && MPROFILE_KERNEL calling sequence
- */
- if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
- pop = ppc_inst(PPC_RAW_NOP());
- else
- pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
-
- if (patch_instruction((u32 *)ip, pop)) {
- pr_err("Patching NOP failed.\n");
- return -EPERM;
- }
-
- return 0;
-}
-#else
-static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
-{
- return 0;
-}
-#endif /* CONFIG_MODULES */
-
static unsigned long find_ftrace_tramp(unsigned long ip)
{
int i;
- /*
- * We have the compiler generated long_branch tramps at the end
- * and we prefer those
- */
- for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
if (!ftrace_tramps[i])
continue;
else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
@@ -233,449 +94,200 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
return 0;
}
-static int add_ftrace_tramp(unsigned long tramp)
+static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
{
- int i;
-
- for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
- if (!ftrace_tramps[i]) {
- ftrace_tramps[i] = tramp;
- return 0;
- }
-
- return -1;
-}
-
-/*
- * If this is a compiler generated long_branch trampoline (essentially, a
- * trampoline that has a branch to _mcount()), we re-write the branch to
- * instead go to ftrace_[regs_]caller() and note down the location of this
- * trampoline.
- */
-static int setup_mcount_compiler_tramp(unsigned long tramp)
-{
- int i;
- ppc_inst_t op;
- unsigned long ptr;
-
- /* Is this a known long jump tramp? */
- for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
- if (ftrace_tramps[i] == tramp)
- return 0;
-
- /* New trampoline -- read where this goes */
- if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
- pr_debug("Fetching opcode failed.\n");
- return -1;
- }
-
- /* Is this a 24 bit branch? */
- if (!is_b_op(op)) {
- pr_debug("Trampoline is not a long branch tramp.\n");
- return -1;
- }
-
- /* lets find where the pointer goes */
- ptr = find_bl_target(tramp, op);
-
- if (ptr != ppc_global_function_entry((void *)_mcount)) {
- pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
- return -1;
- }
-
- /* Let's re-write the tramp to go to ftrace_[regs_]caller */
- if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
- ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
- else
- ptr = ppc_global_function_entry((void *)ftrace_caller);
-
- if (patch_branch((u32 *)tramp, ptr, 0)) {
- pr_debug("REL24 out of range!\n");
- return -1;
- }
-
- if (add_ftrace_tramp(tramp)) {
- pr_debug("No tramp locations left\n");
- return -1;
- }
-
- return 0;
-}
-
-static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long tramp, ip = rec->ip;
- ppc_inst_t op;
-
- /* Read where this goes */
- if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
- pr_err("Fetching opcode failed.\n");
- return -EFAULT;
- }
-
- /* Make sure that this is still a 24bit jump */
- if (!is_bl_op(op)) {
- pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
- return -EINVAL;
- }
-
- /* Let's find where the pointer goes */
- tramp = find_bl_target(ip, op);
-
- pr_devel("ip:%lx jumps to %lx", ip, tramp);
-
- if (setup_mcount_compiler_tramp(tramp)) {
- /* Are other trampolines reachable? */
- if (!find_ftrace_tramp(ip)) {
- pr_err("No ftrace trampolines reachable from %ps\n",
- (void *)ip);
- return -EINVAL;
- }
- }
-
- if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
- pr_err("Patching NOP failed.\n");
- return -EPERM;
- }
-
- return 0;
-}
-
-int ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long ip = rec->ip;
- ppc_inst_t old, new;
-
- /*
- * If the calling address is more that 24 bits away,
- * then we had to use a trampoline to make the call.
- * Otherwise just update the call site.
- */
- if (test_24bit_addr(ip, addr)) {
- /* within range */
- old = ftrace_call_replace(ip, addr, 1);
- new = ppc_inst(PPC_RAW_NOP());
- return ftrace_modify_code(ip, old, new);
- } else if (core_kernel_text(ip)) {
- return __ftrace_make_nop_kernel(rec, addr);
- } else if (!IS_ENABLED(CONFIG_MODULES)) {
- return -EINVAL;
- }
-
- /*
- * Out of range jumps are called from modules.
- * We should either already have a pointer to the module
- * or it has been passed in.
- */
- if (!rec->arch.mod) {
- if (!mod) {
- pr_err("No module loaded addr=%lx\n", addr);
- return -EFAULT;
- }
- rec->arch.mod = mod;
- } else if (mod) {
- if (mod != rec->arch.mod) {
- pr_err("Record mod %p not equal to passed in mod %p\n",
- rec->arch.mod, mod);
- return -EINVAL;
- }
- /* nothing to do if mod == rec->arch.mod */
- } else
- mod = rec->arch.mod;
-
- return __ftrace_make_nop(mod, rec, addr);
-}
-
-#ifdef CONFIG_MODULES
-/*
- * Examine the existing instructions for __ftrace_make_call.
- * They should effectively be a NOP, and follow formal constraints,
- * depending on the ABI. Return false if they don't.
- */
-static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
-{
- if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
- return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
- else
- return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
- ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
-}
-
-static int
-__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- ppc_inst_t op[2];
- void *ip = (void *)rec->ip;
- unsigned long entry, ptr, tramp;
struct module *mod = rec->arch.mod;
-
- /* read where this goes */
- if (copy_inst_from_kernel_nofault(op, ip))
- return -EFAULT;
-
- if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
- copy_inst_from_kernel_nofault(op + 1, ip + 4))
- return -EFAULT;
-
- if (!expected_nop_sequence(ip, op[0], op[1])) {
- pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
- ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
- return -EINVAL;
- }
-
- /* If we never set up ftrace trampoline(s), then bail */
- if (!mod->arch.tramp ||
- (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
- pr_err("No ftrace trampoline\n");
- return -EINVAL;
- }
-
- if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
- tramp = mod->arch.tramp_regs;
- else
- tramp = mod->arch.tramp;
-
- if (module_trampoline_target(mod, tramp, &ptr)) {
- pr_err("Failed to get trampoline target\n");
- return -EFAULT;
- }
-
- pr_devel("trampoline target %lx", ptr);
-
- entry = ppc_global_function_entry((void *)addr);
- /* This should match what was called */
- if (ptr != entry) {
- pr_err("addr %lx does not match expected %lx\n", ptr, entry);
- return -EINVAL;
- }
-
- if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
- pr_err("REL24 out of range!\n");
- return -EINVAL;
- }
-
- return 0;
-}
-#else
-static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- return 0;
-}
-#endif /* CONFIG_MODULES */
-
-static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
-{
- ppc_inst_t op;
- void *ip = (void *)rec->ip;
- unsigned long tramp, entry, ptr;
-
- /* Make sure we're being asked to patch branch to a known ftrace addr */
- entry = ppc_global_function_entry((void *)ftrace_caller);
- ptr = ppc_global_function_entry((void *)addr);
-
- if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
- entry = ppc_global_function_entry((void *)ftrace_regs_caller);
-
- if (ptr != entry) {
- pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
- return -EINVAL;
- }
-
- /* Make sure we have a nop */
- if (copy_inst_from_kernel_nofault(&op, ip)) {
- pr_err("Unable to read ftrace location %p\n", ip);
- return -EFAULT;
- }
-
- if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
- pr_err("Unexpected call sequence at %p: %08lx\n",
- ip, ppc_inst_as_ulong(op));
- return -EINVAL;
- }
-
- tramp = find_ftrace_tramp((unsigned long)ip);
- if (!tramp) {
- pr_err("No ftrace trampolines reachable from %ps\n", ip);
- return -EINVAL;
- }
-
- if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
- pr_err("Error patching branch to ftrace tramp!\n");
- return -EINVAL;
- }
-
- return 0;
-}
-
-int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
-{
unsigned long ip = rec->ip;
- ppc_inst_t old, new;
+ unsigned long stub;
- /*
- * If the calling address is more that 24 bits away,
- * then we had to use a trampoline to make the call.
- * Otherwise just update the call site.
- */
- if (test_24bit_addr(ip, addr)) {
- /* within range */
- old = ppc_inst(PPC_RAW_NOP());
- new = ftrace_call_replace(ip, addr, 1);
- return ftrace_modify_code(ip, old, new);
+ if (is_offset_in_branch_range(addr - ip)) {
+ /* Within range */
+ stub = addr;
} else if (core_kernel_text(ip)) {
- return __ftrace_make_call_kernel(rec, addr);
- } else if (!IS_ENABLED(CONFIG_MODULES)) {
- /* We should not get here without modules */
+ /* We would be branching to one of our ftrace stubs */
+ stub = find_ftrace_tramp(ip);
+ if (!stub) {
+ pr_err("0x%lx: No ftrace stubs reachable\n", ip);
+ return -EINVAL;
+ }
+ } else if (IS_ENABLED(CONFIG_MODULES)) {
+ /* Module code would be going to one of the module stubs */
+ stub = (addr == (unsigned long)ftrace_caller ? mod->arch.tramp : mod->arch.tramp_regs);
+ } else {
return -EINVAL;
}
- /*
- * Out of range jumps are called from modules.
- * Being that we are converting from nop, it had better
- * already have a module defined.
- */
- if (!rec->arch.mod) {
- pr_err("No module loaded\n");
- return -EINVAL;
- }
-
- return __ftrace_make_call(rec, addr);
+ *call_inst = ftrace_create_branch_inst(ip, stub, 1);
+ return 0;
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
-#ifdef CONFIG_MODULES
-static int
-__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
- unsigned long addr)
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
{
- ppc_inst_t op;
- unsigned long ip = rec->ip;
- unsigned long entry, ptr, tramp;
- struct module *mod = rec->arch.mod;
+ /* This should never be called since we override ftrace_replace_code() */
+ WARN_ON(1);
+ return -EINVAL;
+}
+#endif
- /* If we never set up ftrace trampolines, then bail */
- if (!mod->arch.tramp || !mod->arch.tramp_regs) {
- pr_err("No ftrace trampoline\n");
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ ppc_inst_t old, new;
+ int ret;
+
+ /* This can only ever be called during module load */
+ if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
+ return -EINVAL;
+
+ old = ppc_inst(PPC_RAW_NOP());
+ ret = ftrace_get_call_inst(rec, addr, &new);
+ if (ret)
+ return ret;
+
+ return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
+{
+ /*
+ * This should never be called since we override ftrace_replace_code(),
+ * as well as ftrace_init_nop()
+ */
+ WARN_ON(1);
+ return -EINVAL;
+}
+
+void ftrace_replace_code(int enable)
+{
+ ppc_inst_t old, new, nop_inst, call_inst, new_call_inst;
+ unsigned long ip, new_addr, addr;
+ struct ftrace_rec_iter *iter;
+ struct dyn_ftrace *rec;
+ int ret = 0, update;
+
+ for_ftrace_rec_iter(iter) {
+ rec = ftrace_rec_iter_record(iter);
+ update = ftrace_test_record(rec, enable);
+ ip = rec->ip;
+ new_addr = 0;
+
+ switch (update) {
+ case FTRACE_UPDATE_IGNORE:
+ default:
+ continue;
+ case FTRACE_UPDATE_MODIFY_CALL:
+ addr = ftrace_get_addr_curr(rec);
+ new_addr = ftrace_get_addr_new(rec);
+ break;
+ case FTRACE_UPDATE_MAKE_CALL:
+ addr = ftrace_get_addr_new(rec);
+ break;
+ case FTRACE_UPDATE_MAKE_NOP:
+ addr = ftrace_get_addr_curr(rec);
+ break;
+ }
+ nop_inst = ppc_inst(PPC_RAW_NOP());
+ ret = ftrace_get_call_inst(rec, addr, &call_inst);
+ if (!ret && new_addr)
+ ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
+ if (ret)
+ goto out;
+
+ switch (update) {
+ case FTRACE_UPDATE_MODIFY_CALL:
+ old = call_inst;
+ new = new_call_inst;
+ break;
+ case FTRACE_UPDATE_MAKE_CALL:
+ old = nop_inst;
+ new = call_inst;
+ break;
+ case FTRACE_UPDATE_MAKE_NOP:
+ new = nop_inst;
+ old = call_inst;
+ break;
+ }
+
+ /* old == new when going to .ftrace.text stub for modify */
+ if (!ppc_inst_equal(old, new))
+ ret = ftrace_modify_code(ip, old, new);
+ if (ret)
+ goto out;
+ ftrace_update_record(rec, enable);
+ }
+
+out:
+ if (ret)
+ ftrace_bug(ret, rec);
+ return;
+}
+
+int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
+{
+ unsigned long addr, ip = rec->ip;
+ ppc_inst_t old, new;
+ int ret = 0;
+
+ /* Verify instructions surrounding the ftrace location */
+ if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
+ /* Expect nops */
+ ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
+ if (!ret)
+ ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
+ } else if (IS_ENABLED(CONFIG_PPC32)) {
+ /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
+ ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
+ if (!ret)
+ ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
+ } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
+ /* Expected sequence: 'mflr r0', 'bl _mcount' */
+ ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_MFLR(_R0)));
+ } else {
return -EINVAL;
}
- /* read where this goes */
- if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
- pr_err("Fetching opcode failed.\n");
- return -EFAULT;
- }
+ if (ret)
+ return ret;
- /* Make sure that this is still a 24bit jump */
- if (!is_bl_op(op)) {
- pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
- return -EINVAL;
- }
-
- /* lets find where the pointer goes */
- tramp = find_bl_target(ip, op);
- entry = ppc_global_function_entry((void *)old_addr);
-
- pr_devel("ip:%lx jumps to %lx", ip, tramp);
-
- if (tramp != entry) {
- /* old_addr is not within range, so we must have used a trampoline */
- if (module_trampoline_target(mod, tramp, &ptr)) {
- pr_err("Failed to get trampoline target\n");
+ if (!core_kernel_text(ip)) {
+ if (!mod) {
+ pr_err("0x%lx: No module provided for non-kernel address\n", ip);
return -EFAULT;
}
-
- pr_devel("trampoline target %lx", ptr);
-
- /* This should match what was called */
- if (ptr != entry) {
- pr_err("addr %lx does not match expected %lx\n", ptr, entry);
- return -EINVAL;
- }
+ rec->arch.mod = mod;
}
- /* The new target may be within range */
- if (test_24bit_addr(ip, addr)) {
- /* within range */
- if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
- pr_err("REL24 out of range!\n");
- return -EINVAL;
- }
-
- return 0;
- }
-
- if (rec->flags & FTRACE_FL_REGS)
- tramp = mod->arch.tramp_regs;
- else
- tramp = mod->arch.tramp;
-
- if (module_trampoline_target(mod, tramp, &ptr)) {
- pr_err("Failed to get trampoline target\n");
- return -EFAULT;
- }
-
- pr_devel("trampoline target %lx", ptr);
-
- entry = ppc_global_function_entry((void *)addr);
- /* This should match what was called */
- if (ptr != entry) {
- pr_err("addr %lx does not match expected %lx\n", ptr, entry);
- return -EINVAL;
- }
-
- if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
- pr_err("REL24 out of range!\n");
- return -EINVAL;
- }
-
- return 0;
-}
-#else
-static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
-{
- return 0;
-}
-#endif
-
-int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
- unsigned long addr)
-{
- unsigned long ip = rec->ip;
- ppc_inst_t old, new;
-
- /*
- * If the calling address is more that 24 bits away,
- * then we had to use a trampoline to make the call.
- * Otherwise just update the call site.
- */
- if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
- /* within range */
- old = ftrace_call_replace(ip, old_addr, 1);
- new = ftrace_call_replace(ip, addr, 1);
- return ftrace_modify_code(ip, old, new);
- } else if (core_kernel_text(ip)) {
+ /* Nop-out the ftrace location */
+ new = ppc_inst(PPC_RAW_NOP());
+ addr = MCOUNT_ADDR;
+ if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
+ /* we instead patch-in the 'mflr r0' */
+ old = ppc_inst(PPC_RAW_NOP());
+ new = ppc_inst(PPC_RAW_MFLR(_R0));
+ ret = ftrace_modify_code(ip - 4, old, new);
+ } else if (is_offset_in_branch_range(addr - ip)) {
+ /* Within range */
+ old = ftrace_create_branch_inst(ip, addr, 1);
+ ret = ftrace_modify_code(ip, old, new);
+ } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
/*
- * We always patch out of range locations to go to the regs
- * variant, so there is nothing to do here
+ * We would be branching to a toolchain-generated stub, or to the module _mcount
+ * stub. Let's just confirm we have a 'bl' here.
*/
- return 0;
- } else if (!IS_ENABLED(CONFIG_MODULES)) {
- /* We should not get here without modules */
+ ret = ftrace_read_inst(ip, &old);
+ if (ret)
+ return ret;
+ if (!is_bl_op(old)) {
+ pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
+ return -EINVAL;
+ }
+ ret = patch_instruction((u32 *)ip, new);
+ } else {
return -EINVAL;
}
- /*
- * Out of range jumps are called from modules.
- */
- if (!rec->arch.mod) {
- pr_err("No module loaded\n");
- return -EINVAL;
- }
-
- return __ftrace_modify_call(rec, old_addr, addr);
+ return ret;
}
-#endif
int ftrace_update_ftrace_func(ftrace_func_t func)
{
@@ -684,14 +296,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
int ret;
old = ppc_inst_read((u32 *)&ftrace_call);
- new = ftrace_call_replace(ip, (unsigned long)func, 1);
+ new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
ret = ftrace_modify_code(ip, old, new);
/* Also update the regs callback function */
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
ip = (unsigned long)(&ftrace_regs_call);
old = ppc_inst_read((u32 *)&ftrace_regs_call);
- new = ftrace_call_replace(ip, (unsigned long)func, 1);
+ new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
ret = ftrace_modify_code(ip, old, new);
}
@@ -723,6 +335,17 @@ void ftrace_free_init_tramp(void)
}
}
+static void __init add_ftrace_tramp(unsigned long tramp)
+{
+ int i;
+
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
+ if (!ftrace_tramps[i]) {
+ ftrace_tramps[i] = tramp;
+ return;
+ }
+}
+
int __init ftrace_dyn_arch_init(void)
{
int i;
@@ -745,14 +368,9 @@ int __init ftrace_dyn_arch_init(void)
};
#endif
- unsigned long addr;
+ unsigned long addr = FTRACE_REGS_ADDR;
long reladdr;
- if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
- addr = ppc_global_function_entry((void *)ftrace_regs_caller);
- else
- addr = ppc_global_function_entry((void *)ftrace_caller);
-
if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
for (i = 0; i < 2; i++) {
reladdr = addr - (unsigned long)tramp[i];
@@ -804,8 +422,8 @@ static int ftrace_modify_ftrace_graph_caller(bool enable)
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
return 0;
- old = ftrace_call_replace(ip, enable ? stub : addr, 0);
- new = ftrace_call_replace(ip, enable ? addr : stub, 0);
+ old = ftrace_create_branch_inst(ip, enable ? stub : addr, 0);
+ new = ftrace_create_branch_inst(ip, enable ? addr : stub, 0);
return ftrace_modify_code(ip, old, new);
}
@@ -864,13 +482,3 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
}
#endif
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-
-#ifdef CONFIG_PPC64_ELF_ABI_V1
-char *arch_ftrace_match_adjust(char *str, const char *search)
-{
- if (str[0] == '.' && search[0] != '.')
- return str + 1;
- else
- return str;
-}
-#endif /* CONFIG_PPC64_ELF_ABI_V1 */
diff --git a/arch/powerpc/kernel/trace/ftrace_pg.c b/arch/powerpc/kernel/trace/ftrace_pg.c
new file mode 100644
index 00000000000000..7b85c3b460a3c0
--- /dev/null
+++ b/arch/powerpc/kernel/trace/ftrace_pg.c
@@ -0,0 +1,846 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt at redhat.com>
+ *
+ * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
+ *
+ * Added function graph tracer code, taken from x86 that was written
+ * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
+ *
+ */
+
+#define pr_fmt(fmt) "ftrace-powerpc: " fmt
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/list.h>
+
+#include <asm/cacheflush.h>
+#include <asm/code-patching.h>
+#include <asm/ftrace.h>
+#include <asm/syscall.h>
+#include <asm/inst.h>
+
+/*
+ * We generally only have a single long_branch tramp and at most 2 or 3 plt
+ * tramps generated. But, we don't use the plt tramps currently. We also allot
+ * 2 tramps after .text and .init.text. So, we only end up with around 3 usable
+ * tramps in total. Set aside 8 just to be sure.
+ */
+#define NUM_FTRACE_TRAMPS 8
+static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
+
+static ppc_inst_t
+ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
+{
+ ppc_inst_t op;
+
+ addr = ppc_function_entry((void *)addr);
+
+ /* if (link) set op to 'bl' else 'b' */
+ create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);
+
+ return op;
+}
+
+static inline int
+ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
+{
+ ppc_inst_t replaced;
+
+ /*
+ * Note:
+ * We are paranoid about modifying text, as if a bug was to happen, it
+ * could cause us to read or write to someplace that could cause harm.
+ * Carefully read and modify the code with probe_kernel_*(), and make
+ * sure what we read is what we expected it to be before modifying it.
+ */
+
+ /* read the text we want to modify */
+ if (copy_inst_from_kernel_nofault(&replaced, (void *)ip))
+ return -EFAULT;
+
+ /* Make sure it is what we expect it to be */
+ if (!ppc_inst_equal(replaced, old)) {
+ pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip,
+ ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old));
+ return -EINVAL;
+ }
+
+ /* replace the text with the new text */
+ return patch_instruction((u32 *)ip, new);
+}
+
+/*
+ * Helper functions that are the same for both PPC64 and PPC32.
+ */
+static int test_24bit_addr(unsigned long ip, unsigned long addr)
+{
+ addr = ppc_function_entry((void *)addr);
+
+ return is_offset_in_branch_range(addr - ip);
+}
+
+static int is_bl_op(ppc_inst_t op)
+{
+ return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
+}
+
+static int is_b_op(ppc_inst_t op)
+{
+ return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0);
+}
+
+static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
+{
+ int offset;
+
+ offset = PPC_LI(ppc_inst_val(op));
+ /* make it signed */
+ if (offset & 0x02000000)
+ offset |= 0xfe000000;
+
+ return ip + (long)offset;
+}
+
+#ifdef CONFIG_MODULES
+static int
+__ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long entry, ptr, tramp;
+ unsigned long ip = rec->ip;
+ ppc_inst_t op, pop;
+
+ /* read where this goes */
+ if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
+ pr_err("Fetching opcode failed.\n");
+ return -EFAULT;
+ }
+
+ /* Make sure that this is still a 24bit jump */
+ if (!is_bl_op(op)) {
+ pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+
+ /* lets find where the pointer goes */
+ tramp = find_bl_target(ip, op);
+
+ pr_devel("ip:%lx jumps to %lx", ip, tramp);
+
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ pr_err("Failed to get trampoline target\n");
+ return -EFAULT;
+ }
+
+ pr_devel("trampoline target %lx", ptr);
+
+ entry = ppc_global_function_entry((void *)addr);
+ /* This should match what was called */
+ if (ptr != entry) {
+ pr_err("addr %lx does not match expected %lx\n", ptr, entry);
+ return -EINVAL;
+ }
+
+ if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
+ if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
+ pr_err("Fetching instruction at %lx failed.\n", ip - 4);
+ return -EFAULT;
+ }
+
+ /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */
+ if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) &&
+ !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) {
+ pr_err("Unexpected instruction %08lx around bl _mcount\n",
+ ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+ } else if (IS_ENABLED(CONFIG_PPC64)) {
+ /*
+ * Check what is in the next instruction. We can see ld r2,40(r1), but
+ * on first pass after boot we will see mflr r0.
+ */
+ if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) {
+ pr_err("Fetching op failed.\n");
+ return -EFAULT;
+ }
+
+ if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) {
+ pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC,
+ ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * When using -mprofile-kernel or PPC32 there is no load to jump over.
+ *
+ * Otherwise our original call site looks like:
+ *
+ * bl <tramp>
+ * ld r2,XX(r1)
+ *
+ * Milton Miller pointed out that we can not simply nop the branch.
+ * If a task was preempted when calling a trace function, the nops
+ * will remove the way to restore the TOC in r2 and the r2 TOC will
+ * get corrupted.
+ *
+ * Use a b +8 to jump over the load.
+ */
+ if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32))
+ pop = ppc_inst(PPC_RAW_NOP());
+ else
+ pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */
+
+ if (patch_instruction((u32 *)ip, pop)) {
+ pr_err("Patching NOP failed.\n");
+ return -EPERM;
+ }
+
+ return 0;
+}
+#else
+static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
+{
+ return 0;
+}
+#endif /* CONFIG_MODULES */
+
+static unsigned long find_ftrace_tramp(unsigned long ip)
+{
+ int i;
+
+ /*
+ * We have the compiler generated long_branch tramps at the end
+ * and we prefer those
+ */
+ for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
+ if (!ftrace_tramps[i])
+ continue;
+ else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
+ return ftrace_tramps[i];
+
+ return 0;
+}
+
+static int add_ftrace_tramp(unsigned long tramp)
+{
+ int i;
+
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
+ if (!ftrace_tramps[i]) {
+ ftrace_tramps[i] = tramp;
+ return 0;
+ }
+
+ return -1;
+}
+
+/*
+ * If this is a compiler generated long_branch trampoline (essentially, a
+ * trampoline that has a branch to _mcount()), we re-write the branch to
+ * instead go to ftrace_[regs_]caller() and note down the location of this
+ * trampoline.
+ */
+static int setup_mcount_compiler_tramp(unsigned long tramp)
+{
+ int i;
+ ppc_inst_t op;
+ unsigned long ptr;
+
+ /* Is this a known long jump tramp? */
+ for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
+ if (ftrace_tramps[i] == tramp)
+ return 0;
+
+ /* New trampoline -- read where this goes */
+ if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) {
+ pr_debug("Fetching opcode failed.\n");
+ return -1;
+ }
+
+ /* Is this a 24 bit branch? */
+ if (!is_b_op(op)) {
+ pr_debug("Trampoline is not a long branch tramp.\n");
+ return -1;
+ }
+
+ /* lets find where the pointer goes */
+ ptr = find_bl_target(tramp, op);
+
+ if (ptr != ppc_global_function_entry((void *)_mcount)) {
+ pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr);
+ return -1;
+ }
+
+ /* Let's re-write the tramp to go to ftrace_[regs_]caller */
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ ptr = ppc_global_function_entry((void *)ftrace_regs_caller);
+ else
+ ptr = ppc_global_function_entry((void *)ftrace_caller);
+
+ if (patch_branch((u32 *)tramp, ptr, 0)) {
+ pr_debug("REL24 out of range!\n");
+ return -1;
+ }
+
+ if (add_ftrace_tramp(tramp)) {
+ pr_debug("No tramp locations left\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long tramp, ip = rec->ip;
+ ppc_inst_t op;
+
+ /* Read where this goes */
+ if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
+ pr_err("Fetching opcode failed.\n");
+ return -EFAULT;
+ }
+
+ /* Make sure that this is still a 24bit jump */
+ if (!is_bl_op(op)) {
+ pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+
+ /* Let's find where the pointer goes */
+ tramp = find_bl_target(ip, op);
+
+ pr_devel("ip:%lx jumps to %lx", ip, tramp);
+
+ if (setup_mcount_compiler_tramp(tramp)) {
+ /* Are other trampolines reachable? */
+ if (!find_ftrace_tramp(ip)) {
+ pr_err("No ftrace trampolines reachable from %ps\n",
+ (void *)ip);
+ return -EINVAL;
+ }
+ }
+
+ if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) {
+ pr_err("Patching NOP failed.\n");
+ return -EPERM;
+ }
+
+ return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long ip = rec->ip;
+ ppc_inst_t old, new;
+
+ /*
+ * If the calling address is more that 24 bits away,
+ * then we had to use a trampoline to make the call.
+ * Otherwise just update the call site.
+ */
+ if (test_24bit_addr(ip, addr)) {
+ /* within range */
+ old = ftrace_call_replace(ip, addr, 1);
+ new = ppc_inst(PPC_RAW_NOP());
+ return ftrace_modify_code(ip, old, new);
+ } else if (core_kernel_text(ip)) {
+ return __ftrace_make_nop_kernel(rec, addr);
+ } else if (!IS_ENABLED(CONFIG_MODULES)) {
+ return -EINVAL;
+ }
+
+ /*
+ * Out of range jumps are called from modules.
+ * We should either already have a pointer to the module
+ * or it has been passed in.
+ */
+ if (!rec->arch.mod) {
+ if (!mod) {
+ pr_err("No module loaded addr=%lx\n", addr);
+ return -EFAULT;
+ }
+ rec->arch.mod = mod;
+ } else if (mod) {
+ if (mod != rec->arch.mod) {
+ pr_err("Record mod %p not equal to passed in mod %p\n",
+ rec->arch.mod, mod);
+ return -EINVAL;
+ }
+ /* nothing to do if mod == rec->arch.mod */
+ } else
+ mod = rec->arch.mod;
+
+ return __ftrace_make_nop(mod, rec, addr);
+}
+
+#ifdef CONFIG_MODULES
+/*
+ * Examine the existing instructions for __ftrace_make_call.
+ * They should effectively be a NOP, and follow formal constraints,
+ * depending on the ABI. Return false if they don't.
+ */
+static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
+{
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP()));
+ else
+ return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) &&
+ ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC));
+}
+
+static int
+__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ ppc_inst_t op[2];
+ void *ip = (void *)rec->ip;
+ unsigned long entry, ptr, tramp;
+ struct module *mod = rec->arch.mod;
+
+ /* read where this goes */
+ if (copy_inst_from_kernel_nofault(op, ip))
+ return -EFAULT;
+
+ if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
+ copy_inst_from_kernel_nofault(op + 1, ip + 4))
+ return -EFAULT;
+
+ if (!expected_nop_sequence(ip, op[0], op[1])) {
+ pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip,
+ ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1]));
+ return -EINVAL;
+ }
+
+ /* If we never set up ftrace trampoline(s), then bail */
+ if (!mod->arch.tramp ||
+ (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) {
+ pr_err("No ftrace trampoline\n");
+ return -EINVAL;
+ }
+
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS)
+ tramp = mod->arch.tramp_regs;
+ else
+ tramp = mod->arch.tramp;
+
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ pr_err("Failed to get trampoline target\n");
+ return -EFAULT;
+ }
+
+ pr_devel("trampoline target %lx", ptr);
+
+ entry = ppc_global_function_entry((void *)addr);
+ /* This should match what was called */
+ if (ptr != entry) {
+ pr_err("addr %lx does not match expected %lx\n", ptr, entry);
+ return -EINVAL;
+ }
+
+ if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
+ pr_err("REL24 out of range!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+#else
+static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ return 0;
+}
+#endif /* CONFIG_MODULES */
+
+static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
+{
+ ppc_inst_t op;
+ void *ip = (void *)rec->ip;
+ unsigned long tramp, entry, ptr;
+
+ /* Make sure we're being asked to patch branch to a known ftrace addr */
+ entry = ppc_global_function_entry((void *)ftrace_caller);
+ ptr = ppc_global_function_entry((void *)addr);
+
+ if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ entry = ppc_global_function_entry((void *)ftrace_regs_caller);
+
+ if (ptr != entry) {
+ pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr);
+ return -EINVAL;
+ }
+
+ /* Make sure we have a nop */
+ if (copy_inst_from_kernel_nofault(&op, ip)) {
+ pr_err("Unable to read ftrace location %p\n", ip);
+ return -EFAULT;
+ }
+
+ if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
+ pr_err("Unexpected call sequence at %p: %08lx\n",
+ ip, ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+
+ tramp = find_ftrace_tramp((unsigned long)ip);
+ if (!tramp) {
+ pr_err("No ftrace trampolines reachable from %ps\n", ip);
+ return -EINVAL;
+ }
+
+ if (patch_branch(ip, tramp, BRANCH_SET_LINK)) {
+ pr_err("Error patching branch to ftrace tramp!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long ip = rec->ip;
+ ppc_inst_t old, new;
+
+ /*
+ * If the calling address is more that 24 bits away,
+ * then we had to use a trampoline to make the call.
+ * Otherwise just update the call site.
+ */
+ if (test_24bit_addr(ip, addr)) {
+ /* within range */
+ old = ppc_inst(PPC_RAW_NOP());
+ new = ftrace_call_replace(ip, addr, 1);
+ return ftrace_modify_code(ip, old, new);
+ } else if (core_kernel_text(ip)) {
+ return __ftrace_make_call_kernel(rec, addr);
+ } else if (!IS_ENABLED(CONFIG_MODULES)) {
+ /* We should not get here without modules */
+ return -EINVAL;
+ }
+
+ /*
+ * Out of range jumps are called from modules.
+ * Being that we are converting from nop, it had better
+ * already have a module defined.
+ */
+ if (!rec->arch.mod) {
+ pr_err("No module loaded\n");
+ return -EINVAL;
+ }
+
+ return __ftrace_make_call(rec, addr);
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#ifdef CONFIG_MODULES
+static int
+__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ ppc_inst_t op;
+ unsigned long ip = rec->ip;
+ unsigned long entry, ptr, tramp;
+ struct module *mod = rec->arch.mod;
+
+ /* If we never set up ftrace trampolines, then bail */
+ if (!mod->arch.tramp || !mod->arch.tramp_regs) {
+ pr_err("No ftrace trampoline\n");
+ return -EINVAL;
+ }
+
+ /* read where this goes */
+ if (copy_inst_from_kernel_nofault(&op, (void *)ip)) {
+ pr_err("Fetching opcode failed.\n");
+ return -EFAULT;
+ }
+
+ /* Make sure that this is still a 24bit jump */
+ if (!is_bl_op(op)) {
+ pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op));
+ return -EINVAL;
+ }
+
+ /* lets find where the pointer goes */
+ tramp = find_bl_target(ip, op);
+ entry = ppc_global_function_entry((void *)old_addr);
+
+ pr_devel("ip:%lx jumps to %lx", ip, tramp);
+
+ if (tramp != entry) {
+ /* old_addr is not within range, so we must have used a trampoline */
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ pr_err("Failed to get trampoline target\n");
+ return -EFAULT;
+ }
+
+ pr_devel("trampoline target %lx", ptr);
+
+ /* This should match what was called */
+ if (ptr != entry) {
+ pr_err("addr %lx does not match expected %lx\n", ptr, entry);
+ return -EINVAL;
+ }
+ }
+
+ /* The new target may be within range */
+ if (test_24bit_addr(ip, addr)) {
+ /* within range */
+ if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) {
+ pr_err("REL24 out of range!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+ }
+
+ if (rec->flags & FTRACE_FL_REGS)
+ tramp = mod->arch.tramp_regs;
+ else
+ tramp = mod->arch.tramp;
+
+ if (module_trampoline_target(mod, tramp, &ptr)) {
+ pr_err("Failed to get trampoline target\n");
+ return -EFAULT;
+ }
+
+ pr_devel("trampoline target %lx", ptr);
+
+ entry = ppc_global_function_entry((void *)addr);
+ /* This should match what was called */
+ if (ptr != entry) {
+ pr_err("addr %lx does not match expected %lx\n", ptr, entry);
+ return -EINVAL;
+ }
+
+ if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) {
+ pr_err("REL24 out of range!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+#else
+static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
+{
+ return 0;
+}
+#endif
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ unsigned long ip = rec->ip;
+ ppc_inst_t old, new;
+
+ /*
+ * If the calling address is more that 24 bits away,
+ * then we had to use a trampoline to make the call.
+ * Otherwise just update the call site.
+ */
+ if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) {
+ /* within range */
+ old = ftrace_call_replace(ip, old_addr, 1);
+ new = ftrace_call_replace(ip, addr, 1);
+ return ftrace_modify_code(ip, old, new);
+ } else if (core_kernel_text(ip)) {
+ /*
+ * We always patch out of range locations to go to the regs
+ * variant, so there is nothing to do here
+ */
+ return 0;
+ } else if (!IS_ENABLED(CONFIG_MODULES)) {
+ /* We should not get here without modules */
+ return -EINVAL;
+ }
+
+ /*
+ * Out of range jumps are called from modules.
+ */
+ if (!rec->arch.mod) {
+ pr_err("No module loaded\n");
+ return -EINVAL;
+ }
+
+ return __ftrace_modify_call(rec, old_addr, addr);
+}
+#endif
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long ip = (unsigned long)(&ftrace_call);
+ ppc_inst_t old, new;
+ int ret;
+
+ old = ppc_inst_read((u32 *)&ftrace_call);
+ new = ftrace_call_replace(ip, (unsigned long)func, 1);
+ ret = ftrace_modify_code(ip, old, new);
+
+ /* Also update the regs callback function */
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
+ ip = (unsigned long)(&ftrace_regs_call);
+ old = ppc_inst_read((u32 *)&ftrace_regs_call);
+ new = ftrace_call_replace(ip, (unsigned long)func, 1);
+ ret = ftrace_modify_code(ip, old, new);
+ }
+
+ return ret;
+}
+
+/*
+ * Use the default ftrace_modify_all_code, but without
+ * stop_machine().
+ */
+void arch_ftrace_update_code(int command)
+{
+ ftrace_modify_all_code(command);
+}
+
+#ifdef CONFIG_PPC64
+#define PACATOC offsetof(struct paca_struct, kernel_toc)
+
+extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
+
+void ftrace_free_init_tramp(void)
+{
+ int i;
+
+ for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
+ if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
+ ftrace_tramps[i] = 0;
+ return;
+ }
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+ int i;
+ unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
+ u32 stub_insns[] = {
+ PPC_RAW_LD(_R12, _R13, PACATOC),
+ PPC_RAW_ADDIS(_R12, _R12, 0),
+ PPC_RAW_ADDI(_R12, _R12, 0),
+ PPC_RAW_MTCTR(_R12),
+ PPC_RAW_BCTR()
+ };
+ unsigned long addr;
+ long reladdr;
+
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ addr = ppc_global_function_entry((void *)ftrace_regs_caller);
+ else
+ addr = ppc_global_function_entry((void *)ftrace_caller);
+
+ reladdr = addr - kernel_toc_addr();
+
+ if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {
+ pr_err("Address of %ps out of range of kernel_toc.\n",
+ (void *)addr);
+ return -1;
+ }
+
+ for (i = 0; i < 2; i++) {
+ memcpy(tramp[i], stub_insns, sizeof(stub_insns));
+ tramp[i][1] |= PPC_HA(reladdr);
+ tramp[i][2] |= PPC_LO(reladdr);
+ add_ftrace_tramp((unsigned long)tramp[i]);
+ }
+
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+extern void ftrace_graph_call(void);
+extern void ftrace_graph_stub(void);
+
+static int ftrace_modify_ftrace_graph_caller(bool enable)
+{
+ unsigned long ip = (unsigned long)(&ftrace_graph_call);
+ unsigned long addr = (unsigned long)(&ftrace_graph_caller);
+ unsigned long stub = (unsigned long)(&ftrace_graph_stub);
+ ppc_inst_t old, new;
+
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
+ return 0;
+
+ old = ftrace_call_replace(ip, enable ? stub : addr, 0);
+ new = ftrace_call_replace(ip, enable ? addr : stub, 0);
+
+ return ftrace_modify_code(ip, old, new);
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_ftrace_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_ftrace_graph_caller(false);
+}
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info. Return the address we want to divert to.
+ */
+static unsigned long
+__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
+{
+ unsigned long return_hooker;
+ int bit;
+
+ if (unlikely(ftrace_graph_is_dead()))
+ goto out;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ goto out;
+
+ bit = ftrace_test_recursion_trylock(ip, parent);
+ if (bit < 0)
+ goto out;
+
+ return_hooker = ppc_function_entry(return_to_handler);
+
+ if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
+ parent = return_hooker;
+
+ ftrace_test_recursion_unlock(bit);
+out:
+ return parent;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+ fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+}
+#else
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
+ unsigned long sp)
+{
+ return __prepare_ftrace_return(parent, ip, sp);
+}
+#endif
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_PPC64_ELF_ABI_V1
+char *arch_ftrace_match_adjust(char *str, const char *search)
+{
+ if (str[0] == '.' && search[0] != '.')
+ return str + 1;
+ else
+ return str;
+}
+#endif /* CONFIG_PPC64_ELF_ABI_V1 */
diff --git a/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
new file mode 100755
index 00000000000000..410e349cc48428
--- /dev/null
+++ b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+set -o pipefail
+
+# To debug, uncomment the following line
+# set -x
+
+# Output from -fpatchable-function-entry can only vary on 64le, so this should
+# not be invoked for other targets. Therefore we can pass in -m64 and -mabi
+# explicitly, to take care of toolchains defaulting to other targets.
+
+# Test whether the nops are generated before the global entry point.
+echo "int x; int func() { return x; }" | \
+ $* -m64 -mabi=elfv2 -S -x c -O2 -fpatchable-function-entry=2,2 - -o - 2> /dev/null | \
+ awk 'BEGIN { RS = ";" } /nop\n[[:space:]]*nop\n.*\nfunc:/ { print $0 }' | \
+ grep -q "func:" || exit 0
+
+exit 1
base-commit: 6d40746dbb75f85a18a0df005f1a8d6147abec22
prerequisite-patch-id: 3862cf6dc646260228e50b70c316cf15b1d7f384
prerequisite-patch-id: 859f60071f4e425c806fc7fe6c59e268232050a4
prerequisite-patch-id: ef23f712e50f106d689a550dae0f816285c1db3b
prerequisite-patch-id: 8c6d31bb6ac4e4bef086fe502efa660ae99a96ca
--
2.40.1
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