Messages in this thread | | | From | Quentin Casasnovas <> | Subject | [PATCH 0/7] Detect future mis-uses of __ex_table section. | Date | Tue, 17 Mar 2015 13:39:55 +0100 |
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Hi,
This patch-set adds some sanity checks on the __ex_table section so that it makes it much harder to introduce wrong entries in there. It works by checking every relocation in __ex_table and making sure it points to an executable section and does not point to a list of black-listed sections, like .altinstr_replacement. Patch 6 adds a new script, check_extable.sh, so it can be used to get more human readable diagnostics on where the wrong ex_table entry was added in the code. Here's a truncated example output from v4.0-rc2:
Error: found a reference to .altinstr_replacement in __ex_table: xrstor_state at /home/quentin/linux-2.6/./arch/x86/include/asm/xsave.h:179 (inlined by) fpu_xrstor_checking at /home/quentin/linux-2.6/./arch/x86/include/asm/xsave.h:207 (inlined by) fpu_restore_checking at /home/quentin/linux-2.6/./arch/x86/include/asm/fpu-internal.h:284 (inlined by) kvm_load_guest_fpu at /home/quentin/linux-2.6/arch/x86/kvm/x86.c:6986
This is to prevent future misuses of the __ex_table entry like there was for xsaves/xrstors for example, see upstream commit 06e5801b ("x86/fpu/xsaves: Fix improper uses of __ex_table").
This will potentially break the build for other architectures (tested on x86-64 and sparc), since there might be exotic sections in there that I don't know about.
Quentin
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