From: Masami Hiramatsu <mhiramat@kernel.org>
To: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S . Miller" <davem@davemloft.net>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Ye Xiaolong <xiaolong.ye@intel.com>,
mhiramat@kernel.org
Subject: [RFC PATCH tip/master V3 3/8] kprobes/x86: Use instruction decoder for booster
Date: Wed, 29 Mar 2017 13:59:15 +0900 [thread overview]
Message-ID: <149076354563.22469.13379472209338986858.stgit@devbox> (raw)
In-Reply-To: <149076333370.22469.11135086121721120819.stgit@devbox>
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>
---
arch/x86/kernel/kprobes/core.c | 39 ++++++++++++++++-----------------------
1 file changed, 16 insertions(+), 23 deletions(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 81d4dc7..6327f95 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -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 @@ int can_boost(kprobe_opcode_t *opcodes, void *addr)
/* 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);
}
next prev parent reply other threads:[~2017-03-29 5:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 4:55 [RFC PATCH tip/master V3 0/8] kprobes/x86: Make kprobes instruction buffers read-only Masami Hiramatsu
2017-03-29 4:56 ` [RFC PATCH tip/master V3 1/8] kprobes/x86: Fix not to boost call far instruction Masami Hiramatsu
2017-04-12 7:32 ` [tip:perf/core] kprobes/x86: Fix kprobe-booster not to boost far call instructions tip-bot for Masami Hiramatsu
2017-03-29 4:58 ` [RFC PATCH tip/master V3 2/8] kprobes/x86: Fix the description of __copy_instruction() Masami Hiramatsu
2017-04-12 7:32 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29 4:59 ` Masami Hiramatsu [this message]
2017-04-12 7:33 ` [tip:perf/core] kprobes/x86: Use instruction decoder for booster tip-bot for Masami Hiramatsu
2017-03-29 5:00 ` [RFC PATCH tip/master V3 4/8] kprobes/x86: Do not modify singlestep buffer while resuming Masami Hiramatsu
2017-04-12 7:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29 5:01 ` [RFC PATCH tip/master V3 5/8] kprobes/x86: Make boostable flag boolean Masami Hiramatsu
2017-04-12 7:34 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29 5:02 ` [RFC PATCH tip/master V3 6/8] kprobes/x86: Set kprobes pages readonly Masami Hiramatsu
2017-04-12 7:34 ` [tip:perf/core] kprobes/x86: Set kprobes pages read-only tip-bot for Masami Hiramatsu
2017-03-29 5:03 ` [RFC PATCH tip/master V3 7/8] kprobes/x86: Use probe_kernel_read instead of memcpy Masami Hiramatsu
2017-04-12 7:35 ` [tip:perf/core] kprobes/x86: Use probe_kernel_read() instead of memcpy() tip-bot for Masami Hiramatsu
2017-03-29 5:05 ` [RFC PATCH tip/master V3 8/8] kprobes/x86: Consolidate insn decoder users for copying code Masami Hiramatsu
2017-04-12 7:35 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-04-11 5:44 ` [RFC PATCH tip/master V3 0/8] kprobes/x86: Make kprobes instruction buffers read-only Masami Hiramatsu
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