Messages in this thread | | | Date | Mon, 29 Dec 2014 12:10:56 +0800 | From | Wang Nan <> | Subject | Re: [PATCH v17 11/11] ARM: optprobes: execute instruction during restoring if possible. |
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On 2014/12/29 6:10, Masami Hiramatsu wrote: > (2014/12/27 16:36), Wang Nan wrote: >> This patch removes software emulation or simulation for most of probed >> instructions. If the instruction doesn't use PC relative addressing, >> it will be translated into following instructions in the restore code >> in code template: >> >> ldmia {r0 - r14} // restore all instruction except PC >> <instruction> // direct execute the probed instruction >> b next_insn // branch to next instruction. >> >> Signed-off-by: Wang Nan <wangnan0@huawei.com> >> --- >> arch/arm/include/asm/kprobes.h | 3 +++ >> arch/arm/include/asm/probes.h | 1 + >> arch/arm/probes/kprobes/opt-arm.c | 47 +++++++++++++++++++++++++++++++++++++-- >> 3 files changed, 49 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h >> index 50ff3bc..3ea9be5 100644 >> --- a/arch/arm/include/asm/kprobes.h >> +++ b/arch/arm/include/asm/kprobes.h >> @@ -57,6 +57,9 @@ extern __visible kprobe_opcode_t optprobe_template_call; >> extern __visible kprobe_opcode_t optprobe_template_end; >> extern __visible kprobe_opcode_t optprobe_template_sub_sp; >> extern __visible kprobe_opcode_t optprobe_template_add_sp; >> +extern __visible kprobe_opcode_t optprobe_template_restore_begin; >> +extern __visible kprobe_opcode_t optprobe_template_restore_orig_insn; >> +extern __visible kprobe_opcode_t optprobe_template_restore_end; >> >> #define MAX_OPTIMIZED_LENGTH 4 >> #define MAX_OPTINSN_SIZE \ >> diff --git a/arch/arm/include/asm/probes.h b/arch/arm/include/asm/probes.h >> index ee8725c..8ebbe83 100644 >> --- a/arch/arm/include/asm/probes.h >> +++ b/arch/arm/include/asm/probes.h >> @@ -50,6 +50,7 @@ struct arch_probes_insn { >> #define set_register_nouse(m, n) __clear_register_flag(m, n, REG_NO_USE) >> #define set_register_use(m, n) __set_register_flag(m, n, REG_USE) >> int register_usage_mask; >> + bool kprobe_direct_exec; >> }; >> >> #endif /* __ASSEMBLY__ */ >> diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c >> index 6a60df3..f3bd1cc 100644 >> --- a/arch/arm/probes/kprobes/opt-arm.c >> +++ b/arch/arm/probes/kprobes/opt-arm.c >> @@ -32,6 +32,13 @@ >> #include "core.h" >> >> /* >> + * See register_usage_mask. If the probed instruction doesn't use PC, >> + * we can copy it into template and have it executed directly without >> + * simulation or emulation. >> + */ >> +#define can_kprobe_direct_exec(m) (!((m) & 0xc0000000UL)) > > I think you'd better define a macro for this bitmask. > > >> + >> +/* >> * NOTE: the first sub and add instruction will be modified according >> * to the stack cost of the instruction. >> */ >> @@ -66,7 +73,15 @@ asm ( >> " orrne r2, #1\n" >> " strne r2, [sp, #60] @ set bit0 of PC for thumb\n" >> " msr cpsr_cxsf, r1\n" >> + ".global optprobe_template_restore_begin\n" >> + "optprobe_template_restore_begin:\n" >> " ldmia sp, {r0 - r15}\n" >> + ".global optprobe_template_restore_orig_insn\n" >> + "optprobe_template_restore_orig_insn:\n" >> + " nop\n" >> + ".global optprobe_template_restore_end\n" >> + "optprobe_template_restore_end:\n" >> + " ldmia sp, {r13 - r15}\n" > > Why this can't be a nop too? > > Thank you, >
Good suggestion. I'll send a new version of patch 10 and 11.
Thank you.
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