[PATCH v8 12/30] powerpc: Use a function for reading instructions
Christophe Leroy
christophe.leroy at csgroup.eu
Sun May 17 04:39:19 AEST 2020
Le 06/05/2020 à 05:40, Jordan Niethe a écrit :
> Prefixed instructions will mean there are instructions of different
> length. As a result dereferencing a pointer to an instruction will not
> necessarily give the desired result. Introduce a function for reading
> instructions from memory into the instruction data type.
Shouldn't this function be used in mmu_patch_addis() in mm/nohash/8xx.c ?
Christophe
>
> Reviewed-by: Alistair Popple <alistair at popple.id.au>
> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
> ---
> v4: New to series
> v5: - Rename read_inst() -> probe_kernel_read_inst()
> - No longer modify uprobe probe type in this patch
> v6: - feature-fixups.c: do_final_fixups(): Use here
> - arch_prepare_kprobe(): patch_instruction(): no longer part of this
> patch
> - Move probe_kernel_read_inst() out of this patch
> - Use in uprobes
> v8: style
> ---
> arch/powerpc/include/asm/inst.h | 5 +++++
> arch/powerpc/kernel/kprobes.c | 6 +++---
> arch/powerpc/kernel/mce_power.c | 2 +-
> arch/powerpc/kernel/optprobes.c | 4 ++--
> arch/powerpc/kernel/trace/ftrace.c | 4 ++--
> arch/powerpc/kernel/uprobes.c | 2 +-
> arch/powerpc/lib/code-patching.c | 26 ++++++++++++++------------
> arch/powerpc/lib/feature-fixups.c | 4 ++--
> arch/powerpc/xmon/xmon.c | 6 +++---
> 9 files changed, 33 insertions(+), 26 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
> index 19d8bb7a1c2b..552e953bf04f 100644
> --- a/arch/powerpc/include/asm/inst.h
> +++ b/arch/powerpc/include/asm/inst.h
> @@ -27,6 +27,11 @@ static inline struct ppc_inst ppc_inst_swab(struct ppc_inst x)
> return ppc_inst(swab32(ppc_inst_val(x)));
> }
>
> +static inline struct ppc_inst ppc_inst_read(const struct ppc_inst *ptr)
> +{
> + return *ptr;
> +}
> +
> static inline bool ppc_inst_equal(struct ppc_inst x, struct ppc_inst y)
> {
> return ppc_inst_val(x) == ppc_inst_val(y);
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index a08ae5803622..f64312dca84f 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -106,7 +106,7 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
> int arch_prepare_kprobe(struct kprobe *p)
> {
> int ret = 0;
> - struct ppc_inst insn = *(struct ppc_inst *)p->addr;
> + struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
>
> if ((unsigned long)p->addr & 0x03) {
> printk("Attempt to register kprobe at an unaligned address\n");
> @@ -127,7 +127,7 @@ int arch_prepare_kprobe(struct kprobe *p)
> if (!ret) {
> memcpy(p->ainsn.insn, p->addr,
> MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
> - p->opcode = *p->addr;
> + p->opcode = ppc_inst_val(insn);
> flush_icache_range((unsigned long)p->ainsn.insn,
> (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
> }
> @@ -217,7 +217,7 @@ NOKPROBE_SYMBOL(arch_prepare_kretprobe);
> static int try_to_emulate(struct kprobe *p, struct pt_regs *regs)
> {
> int ret;
> - struct ppc_inst insn = *(struct ppc_inst *)p->ainsn.insn;
> + struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->ainsn.insn);
>
> /* regs->nip is also adjusted if emulate_step returns 1 */
> ret = emulate_step(regs, insn);
> diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
> index cd23218c60bb..45c51ba0071b 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,
> pfn = addr_to_pfn(regs, regs->nip);
> if (pfn != ULONG_MAX) {
> instr_addr = (pfn << PAGE_SHIFT) + (regs->nip & ~PAGE_MASK);
> - instr = *(struct ppc_inst *)(instr_addr);
> + instr = ppc_inst_read((struct ppc_inst *)instr_addr);
> if (!analyse_instr(&op, &tmp, instr)) {
> pfn = addr_to_pfn(regs, op.ea);
> *addr = op.ea;
> diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
> index 5a71fef71c22..52c1ab3f85aa 100644
> --- a/arch/powerpc/kernel/optprobes.c
> +++ b/arch/powerpc/kernel/optprobes.c
> @@ -100,9 +100,9 @@ static unsigned long can_optimize(struct kprobe *p)
> * Ensure that the instruction is not a conditional branch,
> * and that can be emulated.
> */
> - if (!is_conditional_branch(*(struct ppc_inst *)p->ainsn.insn) &&
> + if (!is_conditional_branch(ppc_inst_read((struct ppc_inst *)p->ainsn.insn)) &&
> analyse_instr(&op, ®s,
> - *(struct ppc_inst *)p->ainsn.insn) == 1) {
> + ppc_inst_read((struct ppc_inst *)p->ainsn.insn)) == 1) {
> emulate_update_regs(®s, &op);
> nip = regs.nip;
> }
> diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
> index 3117ed675735..acd5b889815f 100644
> --- a/arch/powerpc/kernel/trace/ftrace.c
> +++ b/arch/powerpc/kernel/trace/ftrace.c
> @@ -848,7 +848,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
> struct ppc_inst old, new;
> int ret;
>
> - old = *(struct ppc_inst *)&ftrace_call;
> + old = ppc_inst_read((struct ppc_inst *)&ftrace_call);
> new = ftrace_call_replace(ip, (unsigned long)func, 1);
> ret = ftrace_modify_code(ip, old, new);
>
> @@ -856,7 +856,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
> /* Also update the regs callback function */
> if (!ret) {
> ip = (unsigned long)(&ftrace_regs_call);
> - old = *(struct ppc_inst *)&ftrace_regs_call;
> + old = ppc_inst_read((struct ppc_inst *)&ftrace_regs_call);
> new = ftrace_call_replace(ip, (unsigned long)func, 1);
> ret = ftrace_modify_code(ip, old, new);
> }
> diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
> index 31c870287f2b..6893d40a48c5 100644
> --- a/arch/powerpc/kernel/uprobes.c
> +++ b/arch/powerpc/kernel/uprobes.c
> @@ -174,7 +174,7 @@ 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, ppc_inst_read(&auprobe->insn));
> if (ret > 0)
> return true;
>
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index 1dff9d9d6645..435fc8e9f45d 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -348,9 +348,9 @@ static unsigned long branch_bform_target(const struct ppc_inst *instr)
>
> unsigned long branch_target(const struct ppc_inst *instr)
> {
> - if (instr_is_branch_iform(*instr))
> + if (instr_is_branch_iform(ppc_inst_read(instr)))
> return branch_iform_target(instr);
> - else if (instr_is_branch_bform(*instr))
> + else if (instr_is_branch_bform(ppc_inst_read(instr)))
> return branch_bform_target(instr);
>
> return 0;
> @@ -358,7 +358,8 @@ unsigned long branch_target(const struct ppc_inst *instr)
>
> int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
> {
> - if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
> + if (instr_is_branch_iform(ppc_inst_read(instr)) ||
> + instr_is_branch_bform(ppc_inst_read(instr)))
> return branch_target(instr) == addr;
>
> return 0;
> @@ -368,13 +369,14 @@ int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
> const struct ppc_inst *src)
> {
> unsigned long target;
> -
> target = branch_target(src);
>
> - if (instr_is_branch_iform(*src))
> - return create_branch(instr, dest, target, ppc_inst_val(*src));
> - else if (instr_is_branch_bform(*src))
> - return create_cond_branch(instr, dest, target, ppc_inst_val(*src));
> + if (instr_is_branch_iform(ppc_inst_read(src)))
> + return create_branch(instr, dest, target,
> + ppc_inst_val(ppc_inst_read(src)));
> + else if (instr_is_branch_bform(ppc_inst_read(src)))
> + return create_cond_branch(instr, dest, target,
> + ppc_inst_val(ppc_inst_read(src)));
>
> return 1;
> }
> @@ -598,7 +600,7 @@ static void __init test_translate_branch(void)
> patch_instruction(q, instr);
> check(instr_is_branch_to_addr(p, addr));
> check(instr_is_branch_to_addr(q, addr));
> - check(ppc_inst_equal(*q, ppc_inst(0x4a000000)));
> + check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
>
> /* Maximum positive case, move x to x - 32 MB + 4 */
> p = buf + 0x2000000;
> @@ -609,7 +611,7 @@ static void __init test_translate_branch(void)
> patch_instruction(q, instr);
> check(instr_is_branch_to_addr(p, addr));
> check(instr_is_branch_to_addr(q, addr));
> - check(ppc_inst_equal(*q, ppc_inst(0x49fffffc)));
> + check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
>
> /* Jump to x + 16 MB moved to x + 20 MB */
> p = buf;
> @@ -655,7 +657,7 @@ static void __init test_translate_branch(void)
> patch_instruction(q, instr);
> check(instr_is_branch_to_addr(p, addr));
> check(instr_is_branch_to_addr(q, addr));
> - check(ppc_inst_equal(*q, ppc_inst(0x43ff8000)));
> + check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
>
> /* Maximum positive case, move x to x - 32 KB + 4 */
> p = buf + 0x8000;
> @@ -667,7 +669,7 @@ static void __init test_translate_branch(void)
> patch_instruction(q, instr);
> check(instr_is_branch_to_addr(p, addr));
> check(instr_is_branch_to_addr(q, addr));
> - check(ppc_inst_equal(*q, ppc_inst(0x43ff7ffc)));
> + check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
>
> /* Jump to x + 12 KB moved to x + 20 KB */
> p = buf;
> diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
> index fb6e8e8abf4e..c0d3ed4efb7e 100644
> --- a/arch/powerpc/lib/feature-fixups.c
> +++ b/arch/powerpc/lib/feature-fixups.c
> @@ -48,7 +48,7 @@ static int patch_alt_instruction(struct ppc_inst *src, struct ppc_inst *dest,
> int err;
> struct ppc_inst instr;
>
> - instr = *src;
> + instr = ppc_inst_read(src);
>
> if (instr_is_relative_branch(*src)) {
> struct ppc_inst *target = (struct ppc_inst *)branch_target(src);
> @@ -403,7 +403,7 @@ static void do_final_fixups(void)
> length = (__end_interrupts - _stext) / sizeof(struct ppc_inst);
>
> while (length--) {
> - raw_patch_instruction(dest, *src);
> + raw_patch_instruction(dest, ppc_inst_read(src));
> src++;
> dest++;
> }
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index e0132d6d24d0..68e0b05d9226 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -702,13 +702,13 @@ 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, ppc_inst_read(bp->instr));
> if (stepped == 0) {
> regs->nip = (unsigned long) &bp->instr[0];
> atomic_inc(&bp->ref_count);
> } else if (stepped < 0) {
> printf("Couldn't single-step %s instruction\n",
> - (IS_RFID(bp->instr[0])? "rfid": "mtmsrd"));
> + IS_RFID(ppc_inst_read(bp->instr))? "rfid": "mtmsrd");
> }
> }
> }
> @@ -949,7 +949,7 @@ static void remove_bpts(void)
> if (mread(bp->address, &instr, 4) == 4
> && ppc_inst_equal(instr, ppc_inst(bpinstr))
> && patch_instruction(
> - (struct ppc_inst *)bp->address, bp->instr[0]) != 0)
> + (struct ppc_inst *)bp->address, ppc_inst_read(bp->instr)) != 0)
> printf("Couldn't remove breakpoint at %lx\n",
> bp->address);
> }
>
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