diff options
| author | Tony Luck | 2016-02-17 10:20:12 -0800 |
|---|---|---|
| committer | Ingo Molnar | 2016-02-18 09:21:46 +0100 |
| commit | 548acf19234dbda5a52d5a8e7e205af46e9da840 (patch) | |
| tree | 4dabffd6070e082620a47de718bbab508f928440 /arch/x86/include/asm/asm.h | |
| parent | 061f817eb6a6f97a7e34b73e5e80baa3a20b7663 (diff) | |
x86/mm: Expand the exception table logic to allow new handling options
Huge amounts of help from Andy Lutomirski and Borislav Petkov to
produce this. Andy provided the inspiration to add classes to the
exception table with a clever bit-squeezing trick, Boris pointed
out how much cleaner it would all be if we just had a new field.
Linus Torvalds blessed the expansion with:
' I'd rather not be clever in order to save just a tiny amount of space
in the exception table, which isn't really criticial for anybody. '
The third field is another relative function pointer, this one to a
handler that executes the actions.
We start out with three handlers:
1: Legacy - just jumps the to fixup IP
2: Fault - provide the trap number in %ax to the fixup code
3: Cleaned up legacy for the uaccess error hack
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f6af78fcbd348cf4939875cfda9c19689b5e50b8.1455732970.git.tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/asm.h')
| -rw-r--r-- | arch/x86/include/asm/asm.h | 40 |
1 files changed, 24 insertions, 16 deletions
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h index 189679aba703..f5063b6659eb 100644 --- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -44,19 +44,22 @@ /* Exception table entry */ #ifdef __ASSEMBLY__ -# define _ASM_EXTABLE(from,to) \ +# define _ASM_EXTABLE_HANDLE(from, to, handler) \ .pushsection "__ex_table","a" ; \ - .balign 8 ; \ + .balign 4 ; \ .long (from) - . ; \ .long (to) - . ; \ + .long (handler) - . ; \ .popsection -# define _ASM_EXTABLE_EX(from,to) \ - .pushsection "__ex_table","a" ; \ - .balign 8 ; \ - .long (from) - . ; \ - .long (to) - . + 0x7ffffff0 ; \ - .popsection +# define _ASM_EXTABLE(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_default) + +# define _ASM_EXTABLE_FAULT(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_fault) + +# define _ASM_EXTABLE_EX(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_ext) # define _ASM_NOKPROBE(entry) \ .pushsection "_kprobe_blacklist","aw" ; \ @@ -89,19 +92,24 @@ .endm #else -# define _ASM_EXTABLE(from,to) \ +# define _EXPAND_EXTABLE_HANDLE(x) #x +# define _ASM_EXTABLE_HANDLE(from, to, handler) \ " .pushsection \"__ex_table\",\"a\"\n" \ - " .balign 8\n" \ + " .balign 4\n" \ " .long (" #from ") - .\n" \ " .long (" #to ") - .\n" \ + " .long (" _EXPAND_EXTABLE_HANDLE(handler) ") - .\n" \ " .popsection\n" -# define _ASM_EXTABLE_EX(from,to) \ - " .pushsection \"__ex_table\",\"a\"\n" \ - " .balign 8\n" \ - " .long (" #from ") - .\n" \ - " .long (" #to ") - . + 0x7ffffff0\n" \ - " .popsection\n" +# define _ASM_EXTABLE(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_default) + +# define _ASM_EXTABLE_FAULT(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_fault) + +# define _ASM_EXTABLE_EX(from, to) \ + _ASM_EXTABLE_HANDLE(from, to, ex_handler_ext) + /* For C file, we already have NOKPROBE_SYMBOL macro */ #endif |