[PATCH v8 12/30] powerpc: Use a function for reading instructions
Jordan Niethe
jniethe5 at gmail.com
Sun May 17 20:44:29 AEST 2020
On Sun, May 17, 2020 at 4:39 AM Christophe Leroy
<christophe.leroy at csgroup.eu> wrote:
>
>
>
> 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
Yes, that would be a good idea. mpe here is a fix, along with one I'll
post for [PATCH v8 11/30] powerpc: Use a datatype for instructions.
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -98,7 +98,7 @@ static void mmu_patch_cmp_limit(s32 *site, unsigned
long mapped)
static void mmu_patch_addis(s32 *site, long simm)
{
- struct ppc_inst instr = *(struct ppc_inst *)patch_site_addr(site);
+ struct ppc_inst instr = ppc_inst_read((struct ppc_inst
*)patch_site_addr(site));
unsigned int val = ppc_inst_val(instr);
val &= 0xffff0000;
--
>
> >
> > 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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