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| author | Jon Medhurst <tixy@yxit.co.uk> | 2011-04-19 10:52:19 +0100 |
|---|---|---|
| committer | Nicolas Pitre <nicolas.pitre@linaro.org> | 2011-04-28 23:41:01 -0400 |
| commit | 94254930786216106100e9a28c9a244df58be61f (patch) | |
| tree | 4c2d0f0cb209b6c6608f129f98ba3a0e38f24d78 /arch/arm | |
| parent | 20e8155e24ba5c04558780d0a8da13c39f98c002 (diff) | |
| download | lwn-94254930786216106100e9a28c9a244df58be61f.tar.gz lwn-94254930786216106100e9a28c9a244df58be61f.zip | |
ARM: kprobes: Add emulation of hint instructions like NOP and WFI
Being able to probe NOP instructions is useful for hard-coding probeable
locations and is used by the kprobes test code.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/kprobes-decode.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c index 6bed8b089af0..03b85ad525ab 100644 --- a/arch/arm/kernel/kprobes-decode.c +++ b/arch/arm/kernel/kprobes-decode.c @@ -1225,6 +1225,30 @@ space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi) if ((insn & 0x0fb00000) == 0x03000000) return prep_emulate_rd12_modify(insn, asi); + /* hints : cccc 0011 0010 0000 xxxx xxxx xxxx xxxx */ + if ((insn & 0x0fff0000) == 0x03200000) { + unsigned op2 = insn & 0x000000ff; + if (op2 == 0x01 || op2 == 0x04) { + /* YIELD : cccc 0011 0010 0000 xxxx xxxx 0000 0001 */ + /* SEV : cccc 0011 0010 0000 xxxx xxxx 0000 0100 */ + asi->insn[0] = insn; + asi->insn_handler = emulate_none; + return INSN_GOOD; + } else if (op2 <= 0x03) { + /* NOP : cccc 0011 0010 0000 xxxx xxxx 0000 0000 */ + /* WFE : cccc 0011 0010 0000 xxxx xxxx 0000 0010 */ + /* WFI : cccc 0011 0010 0000 xxxx xxxx 0000 0011 */ + /* + * We make WFE and WFI true NOPs to avoid stalls due + * to missing events whilst processing the probe. + */ + asi->insn_handler = emulate_nop; + return INSN_GOOD_NO_SLOT; + } + /* For DBG and unallocated hints it's safest to reject them */ + return INSN_REJECTED; + } + /* * MSR : cccc 0011 0x10 xxxx xxxx xxxx xxxx xxxx * ALU op with S bit and Rd == 15 : |