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ARM: kprobes: Decode 32-bit Thumb load/store dual and load/store exclusive instructions

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We reject probing of load/store exclusive instructions because any
emulation routine could never succeed in gaining exclusive access as the
exception framework clears the exclusivity monitor when a probes
breakpoint is hit.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-07-03 14:23:21 +01:00 committed by Tixy
parent eaf1d06500
commit b48354d358
1 changed files with 56 additions and 0 deletions
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56
arch/arm/kernel/kprobes-thumb.c
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@ -50,6 +50,33 @@ t32_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi)
return ret;
}
static void __kprobes
t32_emulate_ldrdstrd(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t insn = p->opcode;
unsigned long pc = thumb_probe_pc(p) & ~3;
int rt1 = (insn >> 12) & 0xf;
int rt2 = (insn >> 8) & 0xf;
int rn = (insn >> 16) & 0xf;
register unsigned long rt1v asm("r0") = regs->uregs[rt1];
register unsigned long rt2v asm("r1") = regs->uregs[rt2];
register unsigned long rnv asm("r2") = (rn == 15) ? pc
: regs->uregs[rn];
__asm__ __volatile__ (
"blx %[fn]"
: "=r" (rt1v), "=r" (rt2v), "=r" (rnv)
: "0" (rt1v), "1" (rt2v), "2" (rnv), [fn] "r" (p->ainsn.insn_fn)
: "lr", "memory", "cc"
);
if (rn != 15)
regs->uregs[rn] = rnv; /* Writeback base register */
regs->uregs[rt1] = rt1v;
regs->uregs[rt2] = rt2v;
}
static const union decode_item t32_table_1110_100x_x0xx[] = {
/* Load/store multiple instructions */
@ -79,6 +106,29 @@ static const union decode_item t32_table_1110_100x_x0xx[] = {
DECODE_END
};
static const union decode_item t32_table_1110_100x_x1xx[] = {
/* Load/store dual, load/store exclusive, table branch */
/* STRD (immediate) 1110 1000 x110 xxxx xxxx xxxx xxxx xxxx */
/* LDRD (immediate) 1110 1000 x111 xxxx xxxx xxxx xxxx xxxx */
DECODE_OR (0xff600000, 0xe8600000),
/* STRD (immediate) 1110 1001 x1x0 xxxx xxxx xxxx xxxx xxxx */
/* LDRD (immediate) 1110 1001 x1x1 xxxx xxxx xxxx xxxx xxxx */
DECODE_EMULATEX (0xff400000, 0xe9400000, t32_emulate_ldrdstrd,
REGS(NOPCWB, NOSPPC, NOSPPC, 0, 0)),
/* STREX 1110 1000 0100 xxxx xxxx xxxx xxxx xxxx */
/* LDREX 1110 1000 0101 xxxx xxxx xxxx xxxx xxxx */
/* STREXB 1110 1000 1100 xxxx xxxx xxxx 0100 xxxx */
/* STREXH 1110 1000 1100 xxxx xxxx xxxx 0101 xxxx */
/* STREXD 1110 1000 1100 xxxx xxxx xxxx 0111 xxxx */
/* LDREXB 1110 1000 1101 xxxx xxxx xxxx 0100 xxxx */
/* LDREXH 1110 1000 1101 xxxx xxxx xxxx 0101 xxxx */
/* LDREXD 1110 1000 1101 xxxx xxxx xxxx 0111 xxxx */
/* And unallocated instructions... */
DECODE_END
};
static const union decode_item t32_table_1111_0xxx___1[] = {
/* Branches and miscellaneous control */
@ -102,6 +152,12 @@ const union decode_item kprobe_decode_thumb32_table[] = {
*/
DECODE_TABLE (0xfe400000, 0xe8000000, t32_table_1110_100x_x0xx),
/*
* Load/store dual, load/store exclusive, table branch
* 1110 100x x1xx xxxx xxxx xxxx xxxx xxxx
*/
DECODE_TABLE (0xfe400000, 0xe8400000, t32_table_1110_100x_x1xx),
/*
* Branches and miscellaneous control
* 1111 0xxx xxxx xxxx 1xxx xxxx xxxx xxxx