Messages in this thread | | | Subject | Re: [PATCH v4 13/16] ARM: Add an emulate flag to the kprobes/uprobes instruction decode functions | From | "Jon Medhurst (Tixy)" <> | Date | Fri, 20 Dec 2013 14:58:02 +0000 |
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On Sun, 2013-12-15 at 23:08 -0500, David Long wrote: > From: "David A. Long" <dave.long@linaro.org> > > Add an emulate flag into the instruction interpreter, primarily for uprobes > support. > > Signed-off-by: David A. Long <dave.long@linaro.org> > --- > arch/arm/kernel/kprobes.c | 3 ++- > arch/arm/kernel/kprobes.h | 1 + > arch/arm/kernel/probes-arm.c | 4 ++-- > arch/arm/kernel/probes-arm.h | 2 +- > arch/arm/kernel/probes-thumb.c | 8 ++++---- > arch/arm/kernel/probes-thumb.h | 4 ++-- > arch/arm/kernel/probes.c | 32 +++++++++++++++++++++++--------- > arch/arm/kernel/probes.h | 2 +- > 8 files changed, 36 insertions(+), 20 deletions(-) > > diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c > index 0d9d49b..04690f9 100644 > --- a/arch/arm/kernel/kprobes.c > +++ b/arch/arm/kernel/kprobes.c > @@ -87,7 +87,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > p->opcode = insn; > p->ainsn.insn = tmp_insn; > > - switch ((*decode_insn)(insn, &p->ainsn, actions)) { > + switch ((*decode_insn)(insn, &p->ainsn, > + true, actions)) {
Any reason why the function args need splitting over two lines?
> case INSN_REJECTED: /* not supported */ > return -EINVAL; >
[...]
> --- a/arch/arm/kernel/probes.c > +++ b/arch/arm/kernel/probes.c > @@ -193,7 +193,7 @@ void __kprobes probes_emulate_none(probes_opcode_t opcode, > */ > static probes_opcode_t __kprobes > prepare_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > - bool thumb) > + bool thumb)
Seems like a spurious indentation change.
> { > #ifdef CONFIG_THUMB2_KERNEL > if (thumb) { > @@ -218,7 +218,7 @@ prepare_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > */ > static void __kprobes > set_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > - bool thumb) > + bool thumb)
Another spurious whitespace change.
> { > #ifdef CONFIG_THUMB2_KERNEL > if (thumb) { > @@ -253,7 +253,7 @@ set_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > * non-zero value, the corresponding nibble in pinsn is validated and modified > * according to the type. > */ > -static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs) > +static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs, bool modify) > { > probes_opcode_t insn = *pinsn; > probes_opcode_t mask = 0xf; /* Start at least significant nibble */ > @@ -317,9 +317,16 @@ static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs) > /* Replace value of nibble with new register number... */ > insn &= ~mask; > insn |= new_bits & mask; > + if (modify) { > + /* Replace value of nibble with new register number */ > + insn &= ~mask; > + insn |= new_bits & mask; > + }
Huh? As is, the above addition doesn't do anything because insn has already been modified. I guess you played with the idea that you needed to avoid changing insn (you don't) and then didn't undo the experiment quite right. :-)
> } > > - *pinsn = insn; > + if (modify) > + *pinsn = insn; > + > return true; > > reject: > @@ -380,14 +387,15 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = { > */ > int __kprobes > probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > - const union decode_item *table, bool thumb, > - const union decode_item *actions) > + const union decode_item *table, bool thumb, > + bool emulate, const union decode_item *actions) > { > struct decode_header *h = (struct decode_header *)table; > struct decode_header *next; > bool matched = false; > > - insn = prepare_emulated_insn(insn, asi, thumb); > + if (emulate) > + insn = prepare_emulated_insn(insn, asi, thumb); > > for (;; h = next) { > enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK; > @@ -402,7 +410,7 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > if (!matched && (insn & h->mask.bits) != h->value.bits) > continue; > > - if (!decode_regs(&insn, regs)) > + if (!decode_regs(&insn, regs, emulate)) > return INSN_REJECTED; > > switch (type) { > @@ -415,7 +423,8 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi, > > case DECODE_TYPE_CUSTOM: { > struct decode_custom *d = (struct decode_custom *)h; > - return actions[d->decoder.bits].decoder(insn, asi, h); > + return actions[d->decoder.bits].decoder(insn, > + asi, h);
No need to split the above line, you haven't changed it and it doesn't exceed 80 characters anyway.
[Rest of patch cut]
-- Tixy
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