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kprobes/x86: Return correct length in __copy_instruction()
On x86-64, __copy_instruction() always returns 0 (error) if the instruction uses %rip-relative addressing. This is because kernel_insn_init() is called the second time for 'insn' instance in such cases and sets all its fields to 0. Because of this, trying to place a kprobe on such instruction will fail, register_kprobe() will return -EINVAL. This patch fixes the problem. Signed-off-by: Eugene Shatokhin <eugene.shatokhin@rosalab.ru> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20150317100918.28349.94654.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@kernel.org>
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parent
107eb964d8
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c80e5c0c23
1 changed files with 6 additions and 3 deletions
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@ -354,6 +354,7 @@ int __copy_instruction(u8 *dest, u8 *src)
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{
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struct insn insn;
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kprobe_opcode_t buf[MAX_INSN_SIZE];
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int length;
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unsigned long recovered_insn =
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recover_probed_instruction(buf, (unsigned long)src);
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@ -361,16 +362,18 @@ int __copy_instruction(u8 *dest, u8 *src)
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return 0;
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kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
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insn_get_length(&insn);
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length = insn.length;
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/* Another subsystem puts a breakpoint, failed to recover */
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if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
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return 0;
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memcpy(dest, insn.kaddr, insn.length);
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memcpy(dest, insn.kaddr, length);
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#ifdef CONFIG_X86_64
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if (insn_rip_relative(&insn)) {
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s64 newdisp;
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u8 *disp;
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kernel_insn_init(&insn, dest, insn.length);
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kernel_insn_init(&insn, dest, length);
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insn_get_displacement(&insn);
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/*
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* The copied instruction uses the %rip-relative addressing
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@ -394,7 +397,7 @@ int __copy_instruction(u8 *dest, u8 *src)
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*(s32 *) disp = (s32) newdisp;
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}
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#endif
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return insn.length;
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return length;
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}
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static int arch_copy_kprobe(struct kprobe *p)
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