[PATCH v5 10/21] powerpc: Use a function for reading instructions
Balamuruhan S
bala24 at linux.ibm.com
Tue Apr 7 20:42:20 AEST 2020
On Mon, 2020-04-06 at 18:09 +1000, Jordan Niethe wrote:
> 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.
>
> 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
> ---
> arch/powerpc/include/asm/inst.h | 5 +++++
> arch/powerpc/kernel/kprobes.c | 11 ++++------
> arch/powerpc/kernel/mce_power.c | 2 +-
> arch/powerpc/kernel/optprobes.c | 4 ++--
> arch/powerpc/kernel/trace/ftrace.c | 33 +++++++++++++++++++-----------
> arch/powerpc/lib/code-patching.c | 23 ++++++++++-----------
> arch/powerpc/lib/feature-fixups.c | 2 +-
> arch/powerpc/xmon/xmon.c | 6 +++---
> 8 files changed, 48 insertions(+), 38 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/inst.h
> b/arch/powerpc/include/asm/inst.h
> index a71decf5f871..369b35ce964c 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 !memcmp(&x, &y, sizeof(struct ppc_inst));
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index 9ed996cb0589..ff53e5ef7e40 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");
> @@ -125,11 +125,8 @@ 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;
> - flush_icache_range((unsigned long)p->ainsn.insn,
> - (unsigned long)p->ainsn.insn +
> sizeof(kprobe_opcode_t));
> + patch_instruction((struct ppc_inst *)p->ainsn.insn, insn);
> + p->opcode = ppc_inst_val(insn);
This is a different change from this commit
-- Bala
> }
>
> p->ainsn.boostable = 0;
> @@ -217,7 +214,7 @@ 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 7118b46a6543..859b602fa270 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 b61bbcee84f4..684640b8fa2e 100644
> --- a/arch/powerpc/kernel/optprobes.c
> +++ b/arch/powerpc/kernel/optprobes.c
> @@ -100,8 +100,8 @@ 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) &&
> - analyse_instr(&op, ®s, *(struct ppc_inst *)p-
> >ainsn.insn) == 1) {
> + if (!is_conditional_branch(ppc_inst_read((struct ppc_inst *)p-
> >ainsn.insn)) &&
> + analyse_instr(&op, ®s, 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 442c62fb68ff..e78742613b36 100644
> --- a/arch/powerpc/kernel/trace/ftrace.c
> +++ b/arch/powerpc/kernel/trace/ftrace.c
> @@ -41,6 +41,12 @@
> #define NUM_FTRACE_TRAMPS 8
> static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];
>
> +static long
> +probe_kernel_read_inst(struct ppc_inst *inst, const void *src)
> +{
> + return probe_kernel_read((void *)inst, src, MCOUNT_INSN_SIZE);
> +}
> +
> static struct ppc_inst
> ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
> {
> @@ -68,7 +74,7 @@ ftrace_modify_code(unsigned long ip, struct ppc_inst old,
> struct ppc_inst new)
> */
>
> /* read the text we want to modify */
> - if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
> + if (probe_kernel_read_inst(&replaced, (void *)ip))
> return -EFAULT;
>
> /* Make sure it is what we expect it to be */
> @@ -130,7 +136,7 @@ __ftrace_make_nop(struct module *mod,
> struct ppc_inst op, pop;
>
> /* read where this goes */
> - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
> + if (probe_kernel_read_inst(&op, (void *)ip)) {
> pr_err("Fetching opcode failed.\n");
> return -EFAULT;
> }
> @@ -164,7 +170,7 @@ __ftrace_make_nop(struct module *mod,
> /* When using -mkernel_profile there is no load to jump over */
> pop = ppc_inst(PPC_INST_NOP);
>
> - if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
> + if (probe_kernel_read_inst(&op, (void *)(ip - 4))) {
> pr_err("Fetching instruction at %lx failed.\n", ip - 4);
> return -EFAULT;
> }
> @@ -196,7 +202,7 @@ __ftrace_make_nop(struct module *mod,
> * 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 (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
> + if (probe_kernel_read_inst(&op, (void *)(ip+4))) {
> pr_err("Fetching op failed.\n");
> return -EFAULT;
> }
> @@ -348,7 +354,7 @@ static int setup_mcount_compiler_tramp(unsigned long
> tramp)
> return -1;
>
> /* New trampoline -- read where this goes */
> - if (probe_kernel_read(&op, (void *)tramp, sizeof(int))) {
> + if (probe_kernel_read_inst(&op, (void *)tramp)) {
> pr_debug("Fetching opcode failed.\n");
> return -1;
> }
> @@ -398,7 +404,7 @@ static int __ftrace_make_nop_kernel(struct dyn_ftrace
> *rec, unsigned long addr)
> struct ppc_inst op;
>
> /* Read where this goes */
> - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
> + if (probe_kernel_read_inst(&op, (void *)ip)) {
> pr_err("Fetching opcode failed.\n");
> return -EFAULT;
> }
> @@ -524,7 +530,10 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long
> addr)
> struct module *mod = rec->arch.mod;
>
> /* read where this goes */
> - if (probe_kernel_read(op, ip, sizeof(op)))
> + if (probe_kernel_read_inst(op, ip))
> + return -EFAULT;
> +
> + if (probe_kernel_read_inst(op + 1, ip + 4))
> return -EFAULT;
>
> if (!expected_nop_sequence(ip, op[0], op[1])) {
> @@ -587,7 +596,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long
> addr)
> unsigned long ip = rec->ip;
>
> /* read where this goes */
> - if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
> + if (probe_kernel_read_inst(&op, (void *)ip))
> return -EFAULT;
>
> /* It should be pointing to a nop */
> @@ -643,7 +652,7 @@ static int __ftrace_make_call_kernel(struct dyn_ftrace
> *rec, unsigned long addr)
> }
>
> /* Make sure we have a nop */
> - if (probe_kernel_read(&op, ip, sizeof(op))) {
> + if (probe_kernel_read_inst(&op, ip)) {
> pr_err("Unable to read ftrace location %p\n", ip);
> return -EFAULT;
> }
> @@ -721,7 +730,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned
> long old_addr,
> }
>
> /* read where this goes */
> - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
> + if (probe_kernel_read_inst(&op, (void *)ip)) {
> pr_err("Fetching opcode failed.\n");
> return -EFAULT;
> }
> @@ -846,7 +855,7 @@ 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);
>
> @@ -854,7 +863,7 @@ 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/lib/code-patching.c b/arch/powerpc/lib/code-
> patching.c
> index 91be4a0b51cb..ba08f3815d00 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -349,9 +349,9 @@ 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;
> @@ -359,7 +359,7 @@ 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 +368,12 @@ int instr_is_branch_to_addr(const struct ppc_inst
> *instr, unsigned long addr)
> 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 +597,7 @@ 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 +608,7 @@ 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 +654,7 @@ 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 +666,7 @@ 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 8c5d0db77013..f00dd13b1c3c 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);
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index e3d8e1b8ce01..5e3949322a6c 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -705,13 +705,13 @@ 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");
> }
> }
> }
> @@ -952,7 +952,7 @@ 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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