Commit 17880e4d authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes/x86: Use instruction decoder for booster 



Use x86 instruction decoder for checking whether the probed
instruction is able to boost or not, instead of hand-written
code.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/149076354563.22469.13379472209338986858.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 129d17e8

arch/x86/kernel/kprobes/core.c

+16 −23
Original line number Diff line number Diff line
@@ -169,35 +169,33 @@ NOKPROBE_SYMBOL(skip_prefixes); 
 */

int can_boost(kprobe_opcode_t *opcodes, void *addr)

{

	struct insn insn;

	kprobe_opcode_t opcode;

	kprobe_opcode_t *orig_opcodes = opcodes;



	if (search_exception_tables((unsigned long)addr))

		return 0;	/* Page fault may occur on this address. */



retry:

	if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)

		return 0;

	opcode = *(opcodes++);

	kernel_insn_init(&insn, (void *)opcodes, MAX_INSN_SIZE);

	insn_get_opcode(&insn);



	/* 2nd-byte opcode */

	if (opcode == 0x0f) {

		if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)

			return 0;

		return test_bit(*opcodes,

	if (insn.opcode.nbytes == 2)

		return test_bit(insn.opcode.bytes[1],

				(unsigned long *)twobyte_is_boostable);

	}



	if (insn.opcode.nbytes != 1)

		return 0;



	/* Can't boost Address-size override prefix */

	if (unlikely(inat_is_address_size_prefix(insn.attr)))

		return 0;



	opcode = insn.opcode.bytes[0];



	switch (opcode & 0xf0) {

#ifdef CONFIG_X86_64

	case 0x40:

		goto retry; /* REX prefix is boostable */

#endif

	case 0x60:

		if (0x63 < opcode && opcode < 0x67)

			goto retry; /* prefixes */

		/* can't boost Address-size override and bound */

		return (opcode != 0x62 && opcode != 0x67);

		/* can't boost "bound" */

		return (opcode != 0x62);

	case 0x70:

		return 0; /* can't boost conditional jump */

	case 0x90:
@@ -212,14 +210,9 @@ retry: 
		/* can boost in/out and absolute jmps */

		return ((opcode & 0x04) || opcode == 0xea);

	case 0xf0:

		if ((opcode & 0x0c) == 0 && opcode != 0xf1)

			goto retry; /* lock/rep(ne) prefix */

		/* clear and set flags are boostable */

		return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));

	default:

		/* segment override prefixes are boostable */

		if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)

			goto retry; /* prefixes */

		/* CS override prefix and call are not boostable */

		return (opcode != 0x2e && opcode != 0x9a);

	}

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