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ARM: kprobes: Add emulation of hint instructions like NOP and WFI

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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>
This commit is contained in:
Jon Medhurst 2011-04-19 10:52:19 +01:00 committed by Nicolas Pitre
parent 20e8155e24
commit 9425493078
1 changed files with 24 additions and 0 deletions
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24
arch/arm/kernel/kprobes-decode.c
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@ -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 :