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authorDenys Vlasenko <dvlasenk@redhat.com>2015-03-25 18:18:13 +0100
committerIngo Molnar <mingo@kernel.org>2015-03-27 09:57:05 +0100
commit146b2b097d7a322b64b88a927fc5d870fc79a60b (patch)
treeaa889ede3648f82802043b5e5ba6913a345eb0fa /arch/x86/kernel/entry_64.S
parent06ab9c1ba6a19977432b6906b0eee84804212dc6 (diff)
x86/asm/entry/64: Use better label name, fix comments
A named label "ret_from_sys_call" implies that there are jumps to this location from elsewhere, as happens with many other labels in this file. But this label is used only by the JMP a few insns above. To make that obvious, use local numeric label instead. Improve comments: "and return regs->ax" isn't too informative. We always return regs->ax. The comment suggesting that it'd be cool to use rip relative addressing for CALL is deleted. It's unclear why that would be an improvement - we aren't striving to use position-independent code here. PIC code here would require something like LEA sys_call_table(%rip),reg + CALL *(reg,%rax*8)... "iret frame is also incomplete" is no longer true, fix that too. Also fix typo in comment. Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Will Drewry <wad@chromium.org> Link: http://lkml.kernel.org/r/1427303896-24023-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/entry_64.S')
-rw-r--r--arch/x86/kernel/entry_64.S13
1 files changed, 6 insertions, 7 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index bf9afadbb99e..9988c4b2de33 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -258,16 +258,15 @@ system_call_fastpath:
andl $__SYSCALL_MASK,%eax
cmpl $__NR_syscall_max,%eax
#endif
- ja ret_from_sys_call /* and return regs->ax */
+ ja 1f /* return -ENOSYS (already in pt_regs->ax) */
movq %r10,%rcx
- call *sys_call_table(,%rax,8) # XXX: rip relative
+ call *sys_call_table(,%rax,8)
movq %rax,RAX(%rsp)
+1:
/*
- * Syscall return path ending with SYSRET (fast path)
- * Has incompletely filled pt_regs, iret frame is also incomplete.
+ * Syscall return path ending with SYSRET (fast path).
+ * Has incompletely filled pt_regs.
*/
-ret_from_sys_call:
-
LOCKDEP_SYS_EXIT
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
@@ -1407,7 +1406,7 @@ ENTRY(nmi)
* NMI.
*/
- /* Use %rdx as out temp variable throughout */
+ /* Use %rdx as our temp variable throughout */
pushq_cfi %rdx
CFI_REL_OFFSET rdx, 0