0dc016dbd8
This patch introduce kprobeopt for ARM 32. Limitations: - Currently only kernel compiled with ARM ISA is supported. - Offset between probe point and optinsn slot must not larger than 32MiB. Masami Hiramatsu suggests replacing 2 words, it will make things complex. Futher patch can make such optimization. Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because ARM instruction is always 4 bytes aligned and 4 bytes long. This patch replace probed instruction by a 'b', branch to trampoline code and then calls optimized_callback(). optimized_callback() calls opt_pre_handler() to execute kprobe handler. It also emulate/simulate replaced instruction. When unregistering kprobe, the deferred manner of unoptimizer may leave branch instruction before optimizer is called. Different from x86_64, which only copy the probed insn after optprobe_template_end and reexecute them, this patch call singlestep to emulate/simulate the insn directly. Futher patch can optimize this behavior. Signed-off-by: Wang Nan <wangnan0@huawei.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Will Deacon <will.deacon@arm.com> Reviewed-by: Jon Medhurst (Tixy) <tixy@linaro.org> Signed-off-by: Jon Medhurst <tixy@linaro.org>
30 lines
563 B
C
30 lines
563 B
C
#ifndef __ASM_ARM_INSN_H
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#define __ASM_ARM_INSN_H
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static inline unsigned long
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arm_gen_nop(void)
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{
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#ifdef CONFIG_THUMB2_KERNEL
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return 0xf3af8000; /* nop.w */
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#else
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return 0xe1a00000; /* mov r0, r0 */
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#endif
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}
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unsigned long
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__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
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static inline unsigned long
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arm_gen_branch(unsigned long pc, unsigned long addr)
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{
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return __arm_gen_branch(pc, addr, false);
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}
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static inline unsigned long
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arm_gen_branch_link(unsigned long pc, unsigned long addr)
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{
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return __arm_gen_branch(pc, addr, true);
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}
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#endif
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