From mboxrd@z Thu Jan 1 00:00:00 1970 From: ben.dooks@codethink.co.uk (Ben Dooks) Date: Fri, 02 Aug 2013 14:58:57 +0100 Subject: [PATCH 1/4] ARM: kprobes: fix instruction fetch order with In-Reply-To: <20130802135727.GA2361@localhost.localdomain> References: <1374786537-10726-1-git-send-email-ben.dooks@codethink.co.uk> <1374786537-10726-2-git-send-email-ben.dooks@codethink.co.uk> <1375084901.3521.3.camel@linaro1.home> <51F968CB.8060605@codethink.co.uk> <20130802135727.GA2361@localhost.localdomain> Message-ID: <51FBBB21.4090804@codethink.co.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/08/13 14:57, Dave Martin wrote: > On Wed, Jul 31, 2013 at 08:43:07PM +0100, Ben Dooks wrote: >> On 29/07/13 09:01, Jon Medhurst (Tixy) wrote: >>> On Thu, 2013-07-25 at 22:08 +0100, Ben Dooks wrote: >>>> If we are running BE8, the data and instruction endian-ness do not >>>> match, so use to correctly translate memory accesses >>>> into ARM instructions. >>>> >>>> Signed-off-by: Ben Dooksy >>>> --- >>>> arch/arm/kernel/kprobes-common.c | 14 ++++++++------ >>>> arch/arm/kernel/kprobes.c | 9 +++++---- >>>> 2 files changed, 13 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c >>>> index 18a7628..c0b202e 100644 >>>> --- a/arch/arm/kernel/kprobes-common.c >>>> +++ b/arch/arm/kernel/kprobes-common.c >>>> @@ -14,6 +14,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> >>>> #include "kprobes.h" >>>> >>>> @@ -305,7 +306,8 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi) >>>> >>>> if (handler) { >>>> /* We can emulate the instruction in (possibly) modified form */ >>>> - asi->insn[0] = (insn& 0xfff00000) | (rn<< 16) | reglist; >>>> + asi->insn[0] = __opcode_to_mem_arm((insn& 0xfff00000) | >>>> + (rn<< 16) | reglist); >>>> asi->insn_handler = handler; >>>> return INSN_GOOD; >>>> } >>>> @@ -338,9 +340,9 @@ prepare_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi, >>>> thumb_insn[2] = 0x4770; /* Thumb bx lr */ >>> >>> The line above and the one before it not in this diff also need fixing >>> by changing to __opcode_to_mem_thumb16(0x4770). >> >> IIRC, these are then fixed by the set_emulated instruction, which is >> also why the insn return is not swapped. >> >>>> return insn; >>>> } >>>> - asi->insn[1] = 0xe12fff1e; /* ARM bx lr */ >>>> + asi->insn[1] = __opcode_to_mem_arm(0xe12fff1e); /* ARM bx lr */ >>>> #else >>>> - asi->insn[1] = 0xe1a0f00e; /* mov pc, lr */ >>>> + asi->insn[1] = __opcode_to_mem_arm(0xe1a0f00e); /* mov pc, lr */ >>>> #endif >>>> /* Make an ARM instruction unconditional */ >>>> if (insn< 0xe0000000) >>>> @@ -360,12 +362,12 @@ set_emulated_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi, >>>> if (thumb) { >>>> u16 *ip = (u16 *)asi->insn; >>>> if (is_wide_instruction(insn)) >>>> - *ip++ = insn>> 16; >>>> - *ip++ = insn; >>>> + *ip++ = ___asm_opcode_to_mem_thumb16(insn>> 16); >>>> + *ip++ = ___asm_opcode_to_mem_thumb16(insn); >>> >>> >>> Should these two ___asm_opcode_thumb32_compose() not be >>> __opcode_thumb32_compose() ? >> >> I decided to leave this as is. > > Although the intent is not made as clear in the header as it could be, > the ___asm() functions are not supposed to be used directly: > __opcode_thumb32_compose() will map to the correct thing based on > whether we are preprocessing assembler or C. > > In particular, ___asm_opcode_thumb32_compose() will give you inefficient > swabbing if used directly in C. > >>>> return; >>>> } >>>> #endif >>>> - asi->insn[0] = insn; >>>> + asi->insn[0] = __opcode_to_mem_arm(insn); >>>> } >>>> >>>> /* >>>> diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c >>>> index 170e9f3..3775af1 100644 >>>> --- a/arch/arm/kernel/kprobes.c >>>> +++ b/arch/arm/kernel/kprobes.c >>>> @@ -26,6 +26,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> >>>> #include "kprobes.h" >>>> @@ -62,10 +63,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) >>>> #ifdef CONFIG_THUMB2_KERNEL >>>> thumb = true; >>>> addr&= ~1; /* Bit 0 would normally be set to indicate Thumb code */ >>>> - insn = ((u16 *)addr)[0]; >>>> + insn = __mem_to_opcode_thumb16(((u16 *)addr)[0]); >>>> if (is_wide_instruction(insn)) { >>>> - insn<<= 16; >>>> - insn |= ((u16 *)addr)[1]; >>>> + u16 inst2 = __mem_to_opcode_thumb16(((u16 *)addr)[1]); >>>> + insn = ___asm_opcode_thumb32_compose(insn, inst2); >>> >>> Again, __opcode_thumb32_compose instead of >>> ___asm_opcode_thumb32_compose > > ditto, this should be changed. > > Cheers > ---Dave Yes, already fixed thanks. -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius