Commit 585deaca authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Linus Torvalds
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[PATCH] kprobe: boost 2byte-opcodes on i386



Previous kprobe-booster patch has not handled any 2byte opcodes and
prefixes.  I checked whole IA32 opcode map and classified it.

This patch enables kprobe to boost those 2byte opcodes and prefixes.
Signed-off-by: default avatarMasami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp>
Cc: Satoshi Oshima <soshima@redhat.com>
Cc: Hideo Aoki <haoki@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6ae7440e
......@@ -57,34 +57,85 @@ static __always_inline void set_jmp_op(void *from, void *to)
/*
* returns non-zero if opcodes can be boosted.
*/
static __always_inline int can_boost(kprobe_opcode_t opcode)
static __always_inline int can_boost(kprobe_opcode_t *opcodes)
{
switch (opcode & 0xf0 ) {
#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
(b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
(b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
(bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
<< (row % 32))
/*
* Undefined/reserved opcodes, conditional jump, Opcode Extension
* Groups, and some special opcodes can not be boost.
*/
static const unsigned long twobyte_is_boostable[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ------------------------------- */
W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */
/* ------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#undef W
kprobe_opcode_t opcode;
kprobe_opcode_t *orig_opcodes = opcodes;
retry:
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
return 0;
opcode = *(opcodes++);
/* 2nd-byte opcode */
if (opcode == 0x0f) {
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
return 0;
return test_bit(*opcodes, twobyte_is_boostable);
}
switch (opcode & 0xf0) {
case 0x60:
if (0x63 < opcode && opcode < 0x67)
goto retry; /* prefixes */
/* can't boost Address-size override and bound */
return (opcode != 0x62 && opcode != 0x67);
case 0x70:
return 0; /* can't boost conditional jump */
case 0x90:
/* can't boost call and pushf */
return opcode != 0x9a && opcode != 0x9c;
case 0xc0:
/* can't boost undefined opcodes and soft-interruptions */
return (0xc1 < opcode && opcode < 0xc6) ||
(0xc7 < opcode && opcode < 0xcc) || opcode == 0xcf;
/* can't boost software-interruptions */
return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
case 0xd0:
/* can boost AA* and XLAT */
return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
case 0xe0:
/* can boost in/out and (may be) jmps */
return (0xe3 < opcode && opcode != 0xe8);
/* 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 can be boost */
return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
default:
/* currently, can't boost 2 bytes opcodes */
return opcode != 0x0f;
if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
goto retry; /* prefixes */
/* can't boost CS override and call */
return (opcode != 0x2e && opcode != 0x9a);
}
}
/*
* returns non-zero if opcode modifies the interrupt flag.
*/
......@@ -109,7 +160,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
p->opcode = *p->addr;
if (can_boost(p->opcode)) {
if (can_boost(p->addr)) {
p->ainsn.boostable = 0;
} else {
p->ainsn.boostable = -1;
......
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