Messages in this thread Patch in this message | | | Date | Tue, 08 Aug 2006 18:18:38 -0700 | From | Jeremy Fitzhardinge <> | Subject | [PATCH 2.6.18-rc3-mm2] KPROBE_ENTRY ends up putting code into .fixup |
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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.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
diff -r 30f9dfcdff81 arch/i386/kernel/entry.S --- a/arch/i386/kernel/entry.S Mon Aug 07 16:08:33 2006 -0700 +++ b/arch/i386/kernel/entry.S Tue Aug 08 17:40:03 2006 -0700 @@ -646,7 +646,7 @@ error_code: call *%edi jmp ret_from_exception CFI_ENDPROC -.previous +.popsection ENTRY(coprocessor_error) RING0_INT_FRAME @@ -722,7 +722,7 @@ debug_stack_correct: call do_debug jmp ret_from_exception CFI_ENDPROC -.previous +.popsection /* * NMI is doubly nasty. It can happen _while_ we're handling @@ -819,7 +819,7 @@ KPROBE_ENTRY(int3) call do_int3 jmp ret_from_exception CFI_ENDPROC -.previous +.popsection ENTRY(overflow) RING0_INT_FRAME @@ -884,7 +884,7 @@ KPROBE_ENTRY(general_protection) CFI_ADJUST_CFA_OFFSET 4 jmp error_code CFI_ENDPROC -.previous +.popsection ENTRY(alignment_check) RING0_EC_FRAME diff -r 30f9dfcdff81 arch/x86_64/kernel/entry.S --- a/arch/x86_64/kernel/entry.S Mon Aug 07 16:08:33 2006 -0700 +++ b/arch/x86_64/kernel/entry.S Tue Aug 08 17:41:13 2006 -0700 @@ -904,7 +904,7 @@ error_kernelspace: je error_swapgs jmp error_sti END(error_entry) - .previous + .popsection /* Reload gs selector with exception handling */ /* edi: new selector */ @@ -1024,7 +1024,7 @@ KPROBE_ENTRY(page_fault) KPROBE_ENTRY(page_fault) errorentry do_page_fault END(page_fault) - .previous + .popsection ENTRY(coprocessor_error) zeroentry do_coprocessor_error @@ -1046,7 +1046,7 @@ KPROBE_ENTRY(debug) paranoidentry do_debug, DEBUG_STACK paranoidexit END(debug) - .previous + .popsection /* runs on exception stack */ KPROBE_ENTRY(nmi) @@ -1061,7 +1061,7 @@ KPROBE_ENTRY(nmi) CFI_ENDPROC #endif END(nmi) - .previous + .popsection KPROBE_ENTRY(int3) INTR_FRAME @@ -1071,7 +1071,7 @@ KPROBE_ENTRY(int3) jmp paranoid_exit1 CFI_ENDPROC END(int3) - .previous + .popsection ENTRY(overflow) zeroentry do_overflow @@ -1120,7 +1120,7 @@ KPROBE_ENTRY(general_protection) KPROBE_ENTRY(general_protection) errorentry do_general_protection END(general_protection) - .previous + .popsection ENTRY(alignment_check) errorentry do_alignment_check diff -r 30f9dfcdff81 include/linux/linkage.h --- a/include/linux/linkage.h Mon Aug 07 16:08:33 2006 -0700 +++ b/include/linux/linkage.h Tue Aug 08 17:41:23 2006 -0700 @@ -35,7 +35,7 @@ #endif #define KPROBE_ENTRY(name) \ - .section .kprobes.text, "ax"; \ + .pushsection .kprobes.text, "ax"; \ ENTRY(name) #ifndef END - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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