aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorPrasanna S.P <prasanna@in.ibm.com>2006-09-26 10:52:34 +0200
committerAndi Kleen <andi@basil.nowhere.org>2006-09-26 10:52:34 +0200
commitd28c4393a7bf558538e9def269c1caeab6ec056f (patch)
treee5319c9b9c8a75d2290f7429ec84884d7e1a91fe
parent3ca113ea74836a80645c79adba24caaa7a74120c (diff)
[PATCH] x86: error_code is not safe for kprobes
This patch moves the entry.S:error_entry to .kprobes.text section, since code marked unsafe for kprobes jumps directly to entry.S::error_entry, that must be marked unsafe as well. This patch also moves all the ".previous.text" asm directives to ".previous" for kprobes section. AK: Following a similar i386 patch from Chuck Ebbert AK: Also merged Jeremy's fix in. +From: Jeremy Fitzhardinge <jeremy@goop.org> KPROBE_ENTRY does a .section .kprobes.text, and expects its users to do a .previous at the end of the function. Unfortunately, if any code within the function switches sections, for example .fixup, then the .previous ends up putting all subsequent code into .fixup. Worse, any subsequent .fixup code gets intermingled with the code its supposed to be fixing (which is also in .fixup). It's surprising this didn't cause more havok. The fix is to use .pushsection/.popsection, so this stuff nests properly. A further cleanup would be to get rid of all .section/.previous pairs, since they're inherently fragile. +From: Chuck Ebbert <76306.1226@compuserve.com> Because code marked unsafe for kprobes jumps directly to entry.S::error_code, that must be marked unsafe as well. The easiest way to do that is to move the page fault entry point to just before error_code and let it inherit the same section. Also moved all the ".previous" asm directives for kprobes sections to column 1 and removed ".text" from them. Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andi Kleen <ak@suse.de>
-rw-r--r--arch/i386/kernel/entry.S25
-rw-r--r--arch/x86_64/kernel/entry.S19
-rw-r--r--include/linux/linkage.h6
3 files changed, 25 insertions, 25 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 87f9f60b803..ba22ec8fab5 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -591,11 +591,9 @@ ENTRY(name) \
/* The include is where all of the SMP etc. interrupts come from */
#include "entry_arch.h"
-ENTRY(divide_error)
- RING0_INT_FRAME
- pushl $0 # no error code
- CFI_ADJUST_CFA_OFFSET 4
- pushl $do_divide_error
+KPROBE_ENTRY(page_fault)
+ RING0_EC_FRAME
+ pushl $do_page_fault
CFI_ADJUST_CFA_OFFSET 4
ALIGN
error_code:
@@ -645,6 +643,7 @@ error_code:
call *%edi
jmp ret_from_exception
CFI_ENDPROC
+KPROBE_END(page_fault)
ENTRY(coprocessor_error)
RING0_INT_FRAME
@@ -720,7 +719,8 @@ debug_stack_correct:
call do_debug
jmp ret_from_exception
CFI_ENDPROC
- .previous .text
+KPROBE_END(debug)
+
/*
* NMI is doubly nasty. It can happen _while_ we're handling
* a debug fault, and the debug fault hasn't yet been able to
@@ -816,7 +816,7 @@ KPROBE_ENTRY(int3)
call do_int3
jmp ret_from_exception
CFI_ENDPROC
- .previous .text
+KPROBE_END(int3)
ENTRY(overflow)
RING0_INT_FRAME
@@ -881,7 +881,7 @@ KPROBE_ENTRY(general_protection)
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
- .previous .text
+KPROBE_END(general_protection)
ENTRY(alignment_check)
RING0_EC_FRAME
@@ -890,13 +890,14 @@ ENTRY(alignment_check)
jmp error_code
CFI_ENDPROC
-KPROBE_ENTRY(page_fault)
- RING0_EC_FRAME
- pushl $do_page_fault
+ENTRY(divide_error)
+ RING0_INT_FRAME
+ pushl $0 # no error code
+ CFI_ADJUST_CFA_OFFSET 4
+ pushl $do_divide_error
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
- .previous .text
#ifdef CONFIG_X86_MCE
ENTRY(machine_check)
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 2092f565aa8..780f9b26169 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -819,7 +819,7 @@ paranoid_schedule\trace:
* Exception entry point. This expects an error code/orig_rax on the stack
* and the exception handler in %rax.
*/
-ENTRY(error_entry)
+KPROBE_ENTRY(error_entry)
_frame RDI
/* rdi slot contains rax, oldrax contains error code */
cld
@@ -903,7 +903,7 @@ error_kernelspace:
cmpq $gs_change,RIP(%rsp)
je error_swapgs
jmp error_sti
-END(error_entry)
+KPROBE_END(error_entry)
/* Reload gs selector with exception handling */
/* edi: new selector */
@@ -1025,8 +1025,7 @@ ENDPROC(execve)
KPROBE_ENTRY(page_fault)
errorentry do_page_fault
-END(page_fault)
- .previous .text
+KPROBE_END(page_fault)
ENTRY(coprocessor_error)
zeroentry do_coprocessor_error
@@ -1047,8 +1046,7 @@ KPROBE_ENTRY(debug)
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_debug, DEBUG_STACK
paranoidexit
-END(debug)
- .previous .text
+KPROBE_END(debug)
/* runs on exception stack */
KPROBE_ENTRY(nmi)
@@ -1062,8 +1060,7 @@ KPROBE_ENTRY(nmi)
jmp paranoid_exit1
CFI_ENDPROC
#endif
-END(nmi)
- .previous .text
+KPROBE_END(nmi)
KPROBE_ENTRY(int3)
INTR_FRAME
@@ -1072,8 +1069,7 @@ KPROBE_ENTRY(int3)
paranoidentry do_int3, DEBUG_STACK
jmp paranoid_exit1
CFI_ENDPROC
-END(int3)
- .previous .text
+KPROBE_END(int3)
ENTRY(overflow)
zeroentry do_overflow
@@ -1121,8 +1117,7 @@ END(stack_segment)
KPROBE_ENTRY(general_protection)
errorentry do_general_protection
-END(general_protection)
- .previous .text
+KPROBE_END(general_protection)
ENTRY(alignment_check)
errorentry do_alignment_check
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index 932021f872d..6c9873f8828 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -35,9 +35,13 @@
#endif
#define KPROBE_ENTRY(name) \
- .section .kprobes.text, "ax"; \
+ .pushsection .kprobes.text, "ax"; \
ENTRY(name)
+#define KPROBE_END(name) \
+ END(name); \
+ .popsection
+
#ifndef END
#define END(name) \
.size name, .-name