Commit-ID: 69e8544cd0056e02965ffb5e8414fb7501a2ee2e
Gitweb: http://git.kernel.org/tip/69e8544cd0056e02965ffb5e8414fb7501a2ee2e
Author: Denys Vlasenko <[email protected]>
AuthorDate: Thu, 26 Feb 2015 14:40:24 -0800
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 4 Mar 2015 22:50:48 +0100
x86/asm/64: Open-code register save/restore in trace_hardirqs*() thunks
This is a preparatory patch for change in "struct pt_regs"
handling in entry_64.S.
trace_hardirqs*() thunks were (ab)using a part of the
'pt_regs' handling code, namely the SAVE_ARGS/RESTORE_ARGS
macros, to save/restore registers across C function calls.
Since SAVE_ARGS is going to be changed, open-code
register saving/restoring here.
Incidentally, this removes a bit of dead code:
one SAVE_ARGS was used just to emit a CFI annotation,
but it also generated unreachable assembly instructions.
Take a page from thunk_32.S and use push/pop instructions
instead of movq, they are far shorter:
1 or 2 bytes versus 5, and no need for instructions to adjust %rsp:
text data bss dec hex filename
333 40 0 373 175 thunk_64_movq.o
104 40 0 144 90 thunk_64_push_pop.o
[ This is ugly as sin, but we'll fix up the ugliness in the next
patch. I see no point in reordering patches just to avoid an
ugly intermediate state. --Andy ]
Signed-off-by: Denys Vlasenko <[email protected]>
Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Will Drewry <[email protected]>
Link:
http://lkml.kernel.org/r/[email protected]
Link:
http://lkml.kernel.org/r/4c979ad604f0f02c5ade3b3da308b53eabd5e198.1424989793.git.l...@amacapital.net
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/lib/thunk_64.S | 46 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S
index b30b5eb..8ec443a 100644
--- a/arch/x86/lib/thunk_64.S
+++ b/arch/x86/lib/thunk_64.S
@@ -17,9 +17,27 @@
CFI_STARTPROC
/* this one pushes 9 elems, the next one would be %rIP */
- SAVE_ARGS
+ pushq_cfi %rdi
+ CFI_REL_OFFSET rdi, 0
+ pushq_cfi %rsi
+ CFI_REL_OFFSET rsi, 0
+ pushq_cfi %rdx
+ CFI_REL_OFFSET rdx, 0
+ pushq_cfi %rcx
+ CFI_REL_OFFSET rcx, 0
+ pushq_cfi %rax
+ CFI_REL_OFFSET rax, 0
+ pushq_cfi %r8
+ CFI_REL_OFFSET r8, 0
+ pushq_cfi %r9
+ CFI_REL_OFFSET r9, 0
+ pushq_cfi %r10
+ CFI_REL_OFFSET r10, 0
+ pushq_cfi %r11
+ CFI_REL_OFFSET r11, 0
.if \put_ret_addr_in_rdi
+ /* 9*8(%rsp) is return addr on stack */
movq_cfi_restore 9*8, rdi
.endif
@@ -45,11 +63,31 @@
#endif
#endif
- /* SAVE_ARGS below is used only for the .cfi directives it contains. */
+#if defined(CONFIG_TRACE_IRQFLAGS) \
+ || defined(CONFIG_DEBUG_LOCK_ALLOC) \
+ || defined(CONFIG_PREEMPT)
CFI_STARTPROC
- SAVE_ARGS
+ CFI_ADJUST_CFA_OFFSET 9*8
restore:
- RESTORE_ARGS
+ popq_cfi %r11
+ CFI_RESTORE r11
+ popq_cfi %r10
+ CFI_RESTORE r10
+ popq_cfi %r9
+ CFI_RESTORE r9
+ popq_cfi %r8
+ CFI_RESTORE r8
+ popq_cfi %rax
+ CFI_RESTORE rax
+ popq_cfi %rcx
+ CFI_RESTORE rcx
+ popq_cfi %rdx
+ CFI_RESTORE rdx
+ popq_cfi %rsi
+ CFI_RESTORE rsi
+ popq_cfi %rdi
+ CFI_RESTORE rdi
ret
CFI_ENDPROC
_ASM_NOKPROBE(restore)
+#endif
--
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