[PATCH 05/18] powerpc sstep: Prepare to support prefixed instructions
Jordan Niethe
jniethe5 at gmail.com
Tue Nov 26 16:21:28 AEDT 2019
Currently all instructions are a single word long. A future ISA version
will include prefixed instructions which have a double word length. The
functions used for analysing and emulating instructions need to be
modified so that they can handle these new instruction types.
A prefixed instruction is a word prefix followed by a word suffix. All
prefixes uniquely have the primary op-code 1. Suffixes may be valid word
instructions or instructions that only exist as suffixes.
In handling prefixed instructions it will be convenient to treat the
suffix and prefix as separate words. To facilitate this modify
analyse_instr() and emulate_step() to take a take a suffix as a
parameter. For word instructions it does not matter what is passed in
here - it will be ignored.
We also define a new flag, PREFIXED, to be used in instruction_op:type.
This flag will indicate when emulating an analysed instruction if the
NIP should be advanced by word length or double word length.
The callers of analyse_instr() and emulate_step() will need their own
changes to be able to support prefixed instructions. For now modify them
to pass in 0 as a suffix.
Note that at this point no prefixed instructions are emulated or
analysed - this is just making it possible to do so.
Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
---
arch/powerpc/include/asm/ppc-opcode.h | 3 +++
arch/powerpc/include/asm/sstep.h | 8 +++++--
arch/powerpc/include/asm/uaccess.h | 30 +++++++++++++++++++++++++++
arch/powerpc/kernel/align.c | 2 +-
arch/powerpc/kernel/hw_breakpoint.c | 4 ++--
arch/powerpc/kernel/kprobes.c | 2 +-
arch/powerpc/kernel/mce_power.c | 2 +-
arch/powerpc/kernel/optprobes.c | 2 +-
arch/powerpc/kernel/uprobes.c | 2 +-
arch/powerpc/kvm/emulate_loadstore.c | 2 +-
arch/powerpc/lib/sstep.c | 12 ++++++-----
arch/powerpc/lib/test_emulate_step.c | 30 +++++++++++++--------------
arch/powerpc/xmon/xmon.c | 4 ++--
13 files changed, 71 insertions(+), 32 deletions(-)
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index c1df75edde44..a1dfa4bdd22f 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -377,6 +377,9 @@
#define PPC_INST_VCMPEQUD 0x100000c7
#define PPC_INST_VCMPEQUB 0x10000006
+/* macro to check if a word is a prefix */
+#define IS_PREFIX(x) (((x) >> 26) == 1)
+
/* macros to insert fields into opcodes */
#define ___PPC_RA(a) (((a) & 0x1f) << 16)
#define ___PPC_RB(b) (((b) & 0x1f) << 11)
diff --git a/arch/powerpc/include/asm/sstep.h b/arch/powerpc/include/asm/sstep.h
index 769f055509c9..6d4cb602e231 100644
--- a/arch/powerpc/include/asm/sstep.h
+++ b/arch/powerpc/include/asm/sstep.h
@@ -89,6 +89,9 @@ enum instruction_type {
#define VSX_LDLEFT 4 /* load VSX register from left */
#define VSX_CHECK_VEC 8 /* check MSR_VEC not MSR_VSX for reg >= 32 */
+/* Prefixed flag, ORed in with type */
+#define PREFIXED 0x800
+
/* Size field in type word */
#define SIZE(n) ((n) << 12)
#define GETSIZE(w) ((w) >> 12)
@@ -132,7 +135,7 @@ union vsx_reg {
* otherwise.
*/
extern int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
- unsigned int instr);
+ unsigned int instr, unsigned int sufx);
/*
* Emulate an instruction that can be executed just by updating
@@ -149,7 +152,8 @@ void emulate_update_regs(struct pt_regs *reg, struct instruction_op *op);
* 0 if it could not be emulated, or -1 for an instruction that
* should not be emulated (rfid, mtmsrd clearing MSR_RI, etc.).
*/
-extern int emulate_step(struct pt_regs *regs, unsigned int instr);
+extern int emulate_step(struct pt_regs *regs, unsigned int instr,
+ unsigned int sufx);
/*
* Emulate a load or store instruction by reading/writing the
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 15002b51ff18..bc585399e0c7 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -423,4 +423,34 @@ extern long __copy_from_user_flushcache(void *dst, const void __user *src,
extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
size_t len);
+/*
+ * When reading an instruction iff it is a prefix, the suffix needs to be also
+ * loaded.
+ */
+#define __get_user_instr(x, y, ptr) \
+({ \
+ long __gui_ret = 0; \
+ y = 0; \
+ __gui_ret = __get_user(x, ptr); \
+ if (!__gui_ret) { \
+ if (IS_PREFIX(x)) \
+ __gui_ret = __get_user(y, ptr + 1); \
+ } \
+ \
+ __gui_ret; \
+})
+
+#define __get_user_instr_inatomic(x, y, ptr) \
+({ \
+ long __gui_ret = 0; \
+ y = 0; \
+ __gui_ret = __get_user_inatomic(x, ptr); \
+ if (!__gui_ret) { \
+ if (IS_PREFIX(x)) \
+ __gui_ret = __get_user_inatomic(y, ptr + 1); \
+ } \
+ \
+ __gui_ret; \
+})
+
#endif /* _ARCH_POWERPC_UACCESS_H */
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index 92045ed64976..245e79792a01 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -334,7 +334,7 @@ int fix_alignment(struct pt_regs *regs)
if ((instr & 0xfc0006fe) == (PPC_INST_COPY & 0xfc0006fe))
return -EIO;
- r = analyse_instr(&op, regs, instr);
+ r = analyse_instr(&op, regs, instr, 0);
if (r < 0)
return -EINVAL;
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 58ce3d37c2a3..f4530961998c 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -248,7 +248,7 @@ static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp,
if (__get_user_inatomic(instr, (unsigned int *)regs->nip))
goto fail;
- ret = analyse_instr(&op, regs, instr);
+ ret = analyse_instr(&op, regs, instr, 0);
type = GETTYPE(op.type);
size = GETSIZE(op.type);
@@ -272,7 +272,7 @@ static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp,
return false;
}
- if (!emulate_step(regs, instr))
+ if (!emulate_step(regs, instr, 0))
goto fail;
return true;
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 2d27ec4feee4..7303fe3856cc 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -219,7 +219,7 @@ static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
unsigned int insn = *p->ainsn.insn;
/* regs->nip is also adjusted if emulate_step returns 1 */
- ret = emulate_step(regs, insn);
+ ret = emulate_step(regs, insn, 0);
if (ret > 0) {
/*
* Once this instruction has been boosted
diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
index 1cbf7f1a4e3d..d862bb549158 100644
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -374,7 +374,7 @@ static int mce_find_instr_ea_and_phys(struct pt_regs *regs, uint64_t *addr,
if (pfn != ULONG_MAX) {
instr_addr = (pfn << PAGE_SHIFT) + (regs->nip & ~PAGE_MASK);
instr = *(unsigned int *)(instr_addr);
- if (!analyse_instr(&op, &tmp, instr)) {
+ if (!analyse_instr(&op, &tmp, instr, 0)) {
pfn = addr_to_pfn(regs, op.ea);
*addr = op.ea;
*phys_addr = (pfn << PAGE_SHIFT);
diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index 024f7aad1952..82dc8a589c87 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -100,7 +100,7 @@ static unsigned long can_optimize(struct kprobe *p)
* and that can be emulated.
*/
if (!is_conditional_branch(*p->ainsn.insn) &&
- analyse_instr(&op, ®s, *p->ainsn.insn) == 1) {
+ analyse_instr(&op, ®s, *p->ainsn.insn, 0) == 1) {
emulate_update_regs(®s, &op);
nip = regs.nip;
}
diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index 1cfef0e5fec5..ab1077dc6148 100644
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c
@@ -173,7 +173,7 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
* emulate_step() returns 1 if the insn was successfully emulated.
* For all other cases, we need to single-step in hardware.
*/
- ret = emulate_step(regs, auprobe->insn);
+ ret = emulate_step(regs, auprobe->insn, 0);
if (ret > 0)
return true;
diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c
index 2e496eb86e94..fcab1f31b48d 100644
--- a/arch/powerpc/kvm/emulate_loadstore.c
+++ b/arch/powerpc/kvm/emulate_loadstore.c
@@ -100,7 +100,7 @@ int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
emulated = EMULATE_FAIL;
vcpu->arch.regs.msr = vcpu->arch.shared->msr;
- if (analyse_instr(&op, &vcpu->arch.regs, inst) == 0) {
+ if (analyse_instr(&op, &vcpu->arch.regs, inst, 0) == 0) {
int type = op.type & INSTR_TYPE_MASK;
int size = GETSIZE(op.type);
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index c077acb983a1..ade3f5eba2e5 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1163,7 +1163,7 @@ static nokprobe_inline int trap_compare(long v1, long v2)
* otherwise.
*/
int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
- unsigned int instr)
+ unsigned int instr, unsigned int sufx)
{
unsigned int opcode, ra, rb, rc, rd, spr, u;
unsigned long int imm;
@@ -2756,7 +2756,8 @@ void emulate_update_regs(struct pt_regs *regs, struct instruction_op *op)
{
unsigned long next_pc;
- next_pc = truncate_if_32bit(regs->msr, regs->nip + 4);
+ next_pc = truncate_if_32bit(regs->msr,
+ regs->nip + ((op->type & PREFIXED) ? 8 : 4));
switch (GETTYPE(op->type)) {
case COMPUTE:
if (op->type & SETREG)
@@ -3101,14 +3102,14 @@ NOKPROBE_SYMBOL(emulate_loadstore);
* or -1 if the instruction is one that should not be stepped,
* such as an rfid, or a mtmsrd that would clear MSR_RI.
*/
-int emulate_step(struct pt_regs *regs, unsigned int instr)
+int emulate_step(struct pt_regs *regs, unsigned int instr, unsigned int sufx)
{
struct instruction_op op;
int r, err, type;
unsigned long val;
unsigned long ea;
- r = analyse_instr(&op, regs, instr);
+ r = analyse_instr(&op, regs, instr, sufx);
if (r < 0)
return r;
if (r > 0) {
@@ -3200,7 +3201,8 @@ int emulate_step(struct pt_regs *regs, unsigned int instr)
return 0;
instr_done:
- regs->nip = truncate_if_32bit(regs->msr, regs->nip + 4);
+ regs->nip = truncate_if_32bit(regs->msr,
+ regs->nip + ((op.type & PREFIXED) ? 8 : 4));
return 1;
}
NOKPROBE_SYMBOL(emulate_step);
diff --git a/arch/powerpc/lib/test_emulate_step.c b/arch/powerpc/lib/test_emulate_step.c
index 42347067739c..9288dc6fc715 100644
--- a/arch/powerpc/lib/test_emulate_step.c
+++ b/arch/powerpc/lib/test_emulate_step.c
@@ -103,7 +103,7 @@ static void __init test_ld(void)
regs.gpr[3] = (unsigned long) &a;
/* ld r5, 0(r3) */
- stepped = emulate_step(®s, TEST_LD(5, 3, 0));
+ stepped = emulate_step(®s, TEST_LD(5, 3, 0), 0);
if (stepped == 1 && regs.gpr[5] == a)
show_result("ld", "PASS");
@@ -121,7 +121,7 @@ static void __init test_lwz(void)
regs.gpr[3] = (unsigned long) &a;
/* lwz r5, 0(r3) */
- stepped = emulate_step(®s, TEST_LWZ(5, 3, 0));
+ stepped = emulate_step(®s, TEST_LWZ(5, 3, 0), 0);
if (stepped == 1 && regs.gpr[5] == a)
show_result("lwz", "PASS");
@@ -141,7 +141,7 @@ static void __init test_lwzx(void)
regs.gpr[5] = 0x8765;
/* lwzx r5, r3, r4 */
- stepped = emulate_step(®s, TEST_LWZX(5, 3, 4));
+ stepped = emulate_step(®s, TEST_LWZX(5, 3, 4), 0);
if (stepped == 1 && regs.gpr[5] == a[2])
show_result("lwzx", "PASS");
else
@@ -159,7 +159,7 @@ static void __init test_std(void)
regs.gpr[5] = 0x5678;
/* std r5, 0(r3) */
- stepped = emulate_step(®s, TEST_STD(5, 3, 0));
+ stepped = emulate_step(®s, TEST_STD(5, 3, 0), 0);
if (stepped == 1 || regs.gpr[5] == a)
show_result("std", "PASS");
else
@@ -184,7 +184,7 @@ static void __init test_ldarx_stdcx(void)
regs.gpr[5] = 0x5678;
/* ldarx r5, r3, r4, 0 */
- stepped = emulate_step(®s, TEST_LDARX(5, 3, 4, 0));
+ stepped = emulate_step(®s, TEST_LDARX(5, 3, 4, 0), 0);
/*
* Don't touch 'a' here. Touching 'a' can do Load/store
@@ -202,7 +202,7 @@ static void __init test_ldarx_stdcx(void)
regs.gpr[5] = 0x9ABC;
/* stdcx. r5, r3, r4 */
- stepped = emulate_step(®s, TEST_STDCX(5, 3, 4));
+ stepped = emulate_step(®s, TEST_STDCX(5, 3, 4), 0);
/*
* Two possible scenarios that indicates successful emulation
@@ -242,7 +242,7 @@ static void __init test_lfsx_stfsx(void)
regs.gpr[4] = 0;
/* lfsx frt10, r3, r4 */
- stepped = emulate_step(®s, TEST_LFSX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_LFSX(10, 3, 4), 0);
if (stepped == 1)
show_result("lfsx", "PASS");
@@ -255,7 +255,7 @@ static void __init test_lfsx_stfsx(void)
c.a = 678.91;
/* stfsx frs10, r3, r4 */
- stepped = emulate_step(®s, TEST_STFSX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_STFSX(10, 3, 4), 0);
if (stepped == 1 && c.b == cached_b)
show_result("stfsx", "PASS");
@@ -285,7 +285,7 @@ static void __init test_lfdx_stfdx(void)
regs.gpr[4] = 0;
/* lfdx frt10, r3, r4 */
- stepped = emulate_step(®s, TEST_LFDX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_LFDX(10, 3, 4), 0);
if (stepped == 1)
show_result("lfdx", "PASS");
@@ -298,7 +298,7 @@ static void __init test_lfdx_stfdx(void)
c.a = 987654.32;
/* stfdx frs10, r3, r4 */
- stepped = emulate_step(®s, TEST_STFDX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_STFDX(10, 3, 4), 0);
if (stepped == 1 && c.b == cached_b)
show_result("stfdx", "PASS");
@@ -344,7 +344,7 @@ static void __init test_lvx_stvx(void)
regs.gpr[4] = 0;
/* lvx vrt10, r3, r4 */
- stepped = emulate_step(®s, TEST_LVX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_LVX(10, 3, 4), 0);
if (stepped == 1)
show_result("lvx", "PASS");
@@ -360,7 +360,7 @@ static void __init test_lvx_stvx(void)
c.b[3] = 498532;
/* stvx vrs10, r3, r4 */
- stepped = emulate_step(®s, TEST_STVX(10, 3, 4));
+ stepped = emulate_step(®s, TEST_STVX(10, 3, 4), 0);
if (stepped == 1 && cached_b[0] == c.b[0] && cached_b[1] == c.b[1] &&
cached_b[2] == c.b[2] && cached_b[3] == c.b[3])
@@ -401,7 +401,7 @@ static void __init test_lxvd2x_stxvd2x(void)
regs.gpr[4] = 0;
/* lxvd2x vsr39, r3, r4 */
- stepped = emulate_step(®s, TEST_LXVD2X(39, 3, 4));
+ stepped = emulate_step(®s, TEST_LXVD2X(39, 3, 4), 0);
if (stepped == 1 && cpu_has_feature(CPU_FTR_VSX)) {
show_result("lxvd2x", "PASS");
@@ -421,7 +421,7 @@ static void __init test_lxvd2x_stxvd2x(void)
c.b[3] = 4;
/* stxvd2x vsr39, r3, r4 */
- stepped = emulate_step(®s, TEST_STXVD2X(39, 3, 4));
+ stepped = emulate_step(®s, TEST_STXVD2X(39, 3, 4), 0);
if (stepped == 1 && cached_b[0] == c.b[0] && cached_b[1] == c.b[1] &&
cached_b[2] == c.b[2] && cached_b[3] == c.b[3] &&
@@ -848,7 +848,7 @@ static int __init emulate_compute_instr(struct pt_regs *regs,
if (!regs || !instr)
return -EINVAL;
- if (analyse_instr(&op, regs, instr) != 1 ||
+ if (analyse_instr(&op, regs, instr, 0) != 1 ||
GETTYPE(op.type) != COMPUTE) {
pr_info("emulation failed, instruction = 0x%08x\n", instr);
return -EFAULT;
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index a7056049709e..f47bd843dc52 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -705,7 +705,7 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) == (MSR_IR|MSR_64BIT)) {
bp = at_breakpoint(regs->nip);
if (bp != NULL) {
- int stepped = emulate_step(regs, bp->instr[0]);
+ int stepped = emulate_step(regs, bp->instr[0], 0);
if (stepped == 0) {
regs->nip = (unsigned long) &bp->instr[0];
atomic_inc(&bp->ref_count);
@@ -1170,7 +1170,7 @@ static int do_step(struct pt_regs *regs)
/* check we are in 64-bit kernel mode, translation enabled */
if ((regs->msr & (MSR_64BIT|MSR_PR|MSR_IR)) == (MSR_64BIT|MSR_IR)) {
if (mread(regs->nip, &instr, 4) == 4) {
- stepped = emulate_step(regs, instr);
+ stepped = emulate_step(regs, instr, 0);
if (stepped < 0) {
printf("Couldn't single-step %s instruction\n",
(IS_RFID(instr)? "rfid": "mtmsrd"));
--
2.20.1
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