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>
39 lines
815 B
C
39 lines
815 B
C
#include <linux/kernel.h>
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#include <linux/jump_label.h>
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#include <asm/patch.h>
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#include <asm/insn.h>
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#ifdef HAVE_JUMP_LABEL
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static void __arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type,
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bool is_static)
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{
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void *addr = (void *)entry->code;
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unsigned int insn;
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if (type == JUMP_LABEL_ENABLE)
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insn = arm_gen_branch(entry->code, entry->target);
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else
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insn = arm_gen_nop();
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if (is_static)
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__patch_text_early(addr, insn);
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else
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patch_text(addr, insn);
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}
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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__arch_jump_label_transform(entry, type, false);
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}
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void arch_jump_label_transform_static(struct jump_entry *entry,
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enum jump_label_type type)
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{
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__arch_jump_label_transform(entry, type, true);
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}
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#endif
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