From mboxrd@z Thu Jan 1 00:00:00 1970 From: tixy@yxit.co.uk (Tixy) Date: Sat, 9 Jul 2011 11:57:09 +0100 Subject: [PATCH 22/51] ARM: kprobes: Decode 16-bit Thumb data-processing instructions In-Reply-To: <1310209058-20980-1-git-send-email-tixy@yxit.co.uk> References: <1310209058-20980-1-git-send-email-tixy@yxit.co.uk> Message-ID: <1310209058-20980-23-git-send-email-tixy@yxit.co.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Jon Medhurst These instructions only operate on the low registers R0-R7, therefore it is possible to emulate them by executing the original instruction unaltered if we restore and save these registers. This is what t16_emulate_loregs does. Some of these instructions don't update the PSR when they execute in an IT block, so there are two flavours of emulation functions: t16_emulate_loregs_{noit}rwflags Signed-off-by: Jon Medhurst --- arch/arm/kernel/kprobes-thumb.c | 81 +++++++++++++++++++++++++++++++++++++++ 1 files changed, 81 insertions(+), 0 deletions(-) diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c index 7dcf6df..e1cef82 100644 --- a/arch/arm/kernel/kprobes-thumb.c +++ b/arch/arm/kernel/kprobes-thumb.c @@ -26,6 +26,42 @@ */ #define current_cond(cpsr) ((cpsr >> 12) & 0xf) +static unsigned long __kprobes +t16_emulate_loregs(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long oldcpsr = regs->ARM_cpsr; + unsigned long newcpsr; + + __asm__ __volatile__ ( + "msr cpsr_fs, %[oldcpsr] \n\t" + "ldmia %[regs], {r0-r7} \n\t" + "blx %[fn] \n\t" + "stmia %[regs], {r0-r7} \n\t" + "mrs %[newcpsr], cpsr \n\t" + : [newcpsr] "=r" (newcpsr) + : [oldcpsr] "r" (oldcpsr), [regs] "r" (regs), + [fn] "r" (p->ainsn.insn_fn) + : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", + "lr", "memory", "cc" + ); + + return (oldcpsr & ~APSR_MASK) | (newcpsr & APSR_MASK); +} + +static void __kprobes +t16_emulate_loregs_rwflags(struct kprobe *p, struct pt_regs *regs) +{ + regs->ARM_cpsr = t16_emulate_loregs(p, regs); +} + +static void __kprobes +t16_emulate_loregs_noitrwflags(struct kprobe *p, struct pt_regs *regs) +{ + unsigned long cpsr = t16_emulate_loregs(p, regs); + if (!in_it_block(cpsr)) + regs->ARM_cpsr = cpsr; +} + static const union decode_item t16_table_1011[] = { /* Miscellaneous 16-bit instructions */ @@ -51,6 +87,51 @@ static const union decode_item t16_table_1011[] = { const union decode_item kprobe_decode_thumb16_table[] = { /* + * Shift (immediate), add, subtract, move, and compare + * 00xx xxxx xxxx xxxx + */ + + /* CMP (immediate) 0010 1xxx xxxx xxxx */ + DECODE_EMULATE (0xf800, 0x2800, t16_emulate_loregs_rwflags), + + /* ADD (register) 0001 100x xxxx xxxx */ + /* SUB (register) 0001 101x xxxx xxxx */ + /* LSL (immediate) 0000 0xxx xxxx xxxx */ + /* LSR (immediate) 0000 1xxx xxxx xxxx */ + /* ASR (immediate) 0001 0xxx xxxx xxxx */ + /* ADD (immediate, Thumb) 0001 110x xxxx xxxx */ + /* SUB (immediate, Thumb) 0001 111x xxxx xxxx */ + /* MOV (immediate) 0010 0xxx xxxx xxxx */ + /* ADD (immediate, Thumb) 0011 0xxx xxxx xxxx */ + /* SUB (immediate, Thumb) 0011 1xxx xxxx xxxx */ + DECODE_EMULATE (0xc000, 0x0000, t16_emulate_loregs_noitrwflags), + + /* + * 16-bit Thumb data-processing instructions + * 0100 00xx xxxx xxxx + */ + + /* TST (register) 0100 0010 00xx xxxx */ + DECODE_EMULATE (0xffc0, 0x4200, t16_emulate_loregs_rwflags), + /* CMP (register) 0100 0010 10xx xxxx */ + /* CMN (register) 0100 0010 11xx xxxx */ + DECODE_EMULATE (0xff80, 0x4280, t16_emulate_loregs_rwflags), + /* AND (register) 0100 0000 00xx xxxx */ + /* EOR (register) 0100 0000 01xx xxxx */ + /* LSL (register) 0100 0000 10xx xxxx */ + /* LSR (register) 0100 0000 11xx xxxx */ + /* ASR (register) 0100 0001 00xx xxxx */ + /* ADC (register) 0100 0001 01xx xxxx */ + /* SBC (register) 0100 0001 10xx xxxx */ + /* ROR (register) 0100 0001 11xx xxxx */ + /* RSB (immediate) 0100 0010 01xx xxxx */ + /* ORR (register) 0100 0011 00xx xxxx */ + /* MUL 0100 0011 00xx xxxx */ + /* BIC (register) 0100 0011 10xx xxxx */ + /* MVN (register) 0100 0011 10xx xxxx */ + DECODE_EMULATE (0xfc00, 0x4000, t16_emulate_loregs_noitrwflags), + + /* * Miscellaneous 16-bit instructions * 1011 xxxx xxxx xxxx */ -- 1.7.2.5