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kprobes/x86: Use instruction decoder for booster

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

Signed-off-by: Masami 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2017-03-29 13:59:15 +09:00 committed by Ingo Molnar
parent 129d17e8e8
commit 17880e4d57
1 changed files with 16 additions and 23 deletions
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39
arch/x86/kernel/kprobes/core.c
View File

@ -169,35 +169,33 @@ NOKPROBE_SYMBOL(skip_prefixes);
*/ */
int can_boost(kprobe_opcode_t *opcodes, void *addr) int can_boost(kprobe_opcode_t *opcodes, void *addr)
{ {
struct insn insn;
kprobe_opcode_t opcode; kprobe_opcode_t opcode;
kprobe_opcode_t *orig_opcodes = opcodes;
if (search_exception_tables((unsigned long)addr)) if (search_exception_tables((unsigned long)addr))
return 0; /* Page fault may occur on this address. */ return 0; /* Page fault may occur on this address. */
retry: kernel_insn_init(&insn, (void *)opcodes, MAX_INSN_SIZE);
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) insn_get_opcode(&insn);
return 0;
opcode = *(opcodes++);
/* 2nd-byte opcode */ /* 2nd-byte opcode */
if (opcode == 0x0f) { if (insn.opcode.nbytes == 2)
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) return test_bit(insn.opcode.bytes[1],
return 0;
return test_bit(*opcodes,
(unsigned long *)twobyte_is_boostable); (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) { switch (opcode & 0xf0) {
#ifdef CONFIG_X86_64
case 0x40:
goto retry; /* REX prefix is boostable */
#endif
case 0x60: case 0x60:
if (0x63 < opcode && opcode < 0x67) /* can't boost "bound" */
goto retry; /* prefixes */ return (opcode != 0x62);
/* can't boost Address-size override and bound */
return (opcode != 0x62 && opcode != 0x67);
case 0x70: case 0x70:
return 0; /* can't boost conditional jump */ return 0; /* can't boost conditional jump */
case 0x90: case 0x90:
@ -212,14 +210,9 @@ int can_boost(kprobe_opcode_t *opcodes, void *addr)
/* can boost in/out and absolute jmps */ /* can boost in/out and absolute jmps */
return ((opcode & 0x04) || opcode == 0xea); return ((opcode & 0x04) || opcode == 0xea);
case 0xf0: case 0xf0:
if ((opcode & 0x0c) == 0 && opcode != 0xf1)
goto retry; /* lock/rep(ne) prefix */
/* clear and set flags are boostable */ /* clear and set flags are boostable */
return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
default: default:
/* segment override prefixes are boostable */
if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
goto retry; /* prefixes */
/* CS override prefix and call are not boostable */ /* CS override prefix and call are not boostable */
return (opcode != 0x2e && opcode != 0x9a); return (opcode != 0x2e && opcode != 0x9a);
} }