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Message-ID: <20140331194359.GA9278@redhat.com>
Date: Mon, 31 Mar 2014 21:43:59 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Ingo Molnar <mingo@...e.hu>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>,
David Long <dave.long@...aro.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
"Frank Ch. Eigler" <fche@...hat.com>,
Jim Keniston <jkenisto@...ibm.com>,
Jonathan Lebon <jlebon@...hat.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/7] uprobes/x86: Fold prepare_fixups() into
arch_uprobe_analyze_insn()
No functional changes, preparation.
Shift the code from prepare_fixups() to arch_uprobe_analyze_insn()
with the following modifications:
- Do not call insn_get_opcode() again, it was already called
by validate_insn_bits().
- Move "case 0xea" up. This way "case 0xff" can fall through
to default case.
- change "case 0xff" to use the nested "switch (MODRM_REG)",
this way the code looks a bit simpler.
- Make the comments look consistent.
While at it, kill the initialization of rip_rela_target_address and
->fixups, we can rely on kzalloc(). We will add the new members into
arch_uprobe, it would be better to assume that everything is zero by
default.
TODO: cleanup/fix the mess in validate_insn_bits() paths:
- validate_insn_64bits() and validate_insn_32bits() should be
unified.
- "ifdef" is not used consistently; if good_insns_64 depends
on CONFIG_X86_64, then probably good_insns_32 should depend
on CONFIG_X86_32/EMULATION
- the usage of mm->context.ia32_compat looks wrong if the task
is TIF_X32.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
arch/x86/kernel/uprobes.c | 110 +++++++++++++++++++--------------------------
1 files changed, 47 insertions(+), 63 deletions(-)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 2ed8459..098e56e 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -53,7 +53,7 @@
#define OPCODE1(insn) ((insn)->opcode.bytes[0])
#define OPCODE2(insn) ((insn)->opcode.bytes[1])
#define OPCODE3(insn) ((insn)->opcode.bytes[2])
-#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value)
+#define MODRM_REG(insn) X86_MODRM_REG((insn)->modrm.value)
#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) | \
@@ -229,63 +229,6 @@ static int validate_insn_32bits(struct arch_uprobe *auprobe, struct insn *insn)
return -ENOTSUPP;
}
-/*
- * Figure out which fixups arch_uprobe_post_xol() will need to perform, and
- * annotate arch_uprobe->fixups accordingly. To start with,
- * arch_uprobe->fixups is either zero or it reflects rip-related fixups.
- */
-static void prepare_fixups(struct arch_uprobe *auprobe, struct insn *insn)
-{
- bool fix_ip = true, fix_call = false; /* defaults */
- int reg;
-
- insn_get_opcode(insn); /* should be a nop */
-
- switch (OPCODE1(insn)) {
- case 0x9d:
- /* popf */
- auprobe->fixups |= UPROBE_FIX_SETF;
- break;
- case 0xc3: /* ret/lret */
- case 0xcb:
- case 0xc2:
- case 0xca:
- /* ip is correct */
- fix_ip = false;
- break;
- case 0xe8: /* call relative - Fix return addr */
- fix_call = true;
- break;
- case 0x9a: /* call absolute - Fix return addr, not ip */
- fix_call = true;
- fix_ip = false;
- break;
- case 0xff:
- insn_get_modrm(insn);
- reg = MODRM_REG(insn);
- if (reg == 2 || reg == 3) {
- /* call or lcall, indirect */
- /* Fix return addr; ip is correct. */
- fix_call = true;
- fix_ip = false;
- } else if (reg == 4 || reg == 5) {
- /* jmp or ljmp, indirect */
- /* ip is correct. */
- fix_ip = false;
- }
- break;
- case 0xea: /* jmp absolute -- ip is correct */
- fix_ip = false;
- break;
- default:
- break;
- }
- if (fix_ip)
- auprobe->fixups |= UPROBE_FIX_IP;
- if (fix_call)
- auprobe->fixups |= UPROBE_FIX_CALL;
-}
-
#ifdef CONFIG_X86_64
/*
* If arch_uprobe->insn doesn't use rip-relative addressing, return
@@ -318,7 +261,6 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, struct ins
if (mm->context.ia32_compat)
return;
- auprobe->rip_rela_target_address = 0x0;
if (!insn_rip_relative(insn))
return;
@@ -421,16 +363,58 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
*/
int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long addr)
{
- int ret;
struct insn insn;
+ bool fix_ip = true, fix_call = false;
+ int ret;
- auprobe->fixups = 0;
ret = validate_insn_bits(auprobe, mm, &insn);
- if (ret != 0)
+ if (ret)
return ret;
+ /*
+ * Figure out which fixups arch_uprobe_post_xol() will need to perform,
+ * and annotate arch_uprobe->fixups accordingly. To start with, ->fixups
+ * is either zero or it reflects rip-related fixups.
+ */
handle_riprel_insn(auprobe, mm, &insn);
- prepare_fixups(auprobe, &insn);
+
+ switch (OPCODE1(&insn)) {
+ case 0x9d: /* popf */
+ auprobe->fixups |= UPROBE_FIX_SETF;
+ break;
+ case 0xc3: /* ret or lret -- ip is correct */
+ case 0xcb:
+ case 0xc2:
+ case 0xca:
+ fix_ip = false;
+ break;
+ case 0xe8: /* call relative - Fix return addr */
+ fix_call = true;
+ break;
+ case 0x9a: /* call absolute - Fix return addr, not ip */
+ fix_call = true;
+ fix_ip = false;
+ break;
+ case 0xea: /* jmp absolute -- ip is correct */
+ fix_ip = false;
+ break;
+ case 0xff:
+ insn_get_modrm(&insn);
+ switch (MODRM_REG(&insn)) {
+ case 2: case 3: /* call or lcall, indirect */
+ fix_call = true;
+ case 4: case 5: /* jmp or ljmp, indirect */
+ fix_ip = false;
+ }
+ break;
+ default:
+ break;
+ }
+
+ if (fix_ip)
+ auprobe->fixups |= UPROBE_FIX_IP;
+ if (fix_call)
+ auprobe->fixups |= UPROBE_FIX_CALL;
return 0;
}
--
1.5.5.1
--
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