korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-16 08:44:21 +08:00
Code Issues Packages Projects Releases Wiki Activity

x86/asm/entry/32: Open-code LOAD_ARGS32

Browse Source 
This macro is small, has only three callsites, and one of them
is slightly different using a conditional parameter.

A few saved lines aren't worth the resulting obfuscation.

Generated machine code is identical.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433271842-9139-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Denys Vlasenko 2015-06-02 21:04:02 +02:00 committed by Ingo Molnar
parent ef0cd5dc25
commit 73cbf68791
1 changed files with 29 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
arch/x86/entry/ia32entry.S
View File

@ -29,28 +29,6 @@
.section .entry.text, "ax"
/*
* Reload arg registers from stack in case ptrace changed them.
* We don't reload %eax because syscall_trace_enter() returned
* the %rax value we should see. Instead, we just truncate that
* value to 32 bits again as we did on entry from user mode.
* If it's a new value set by user_regset during entry tracing,
* this matches the normal truncation of the user-mode value.
* If it's -1 to make us punt the syscall, then (u32)-1 is still
* an appropriately invalid value.
*/
.macro LOAD_ARGS32 _r9=0
.if \_r9
movl R9(%rsp),%r9d
.endif
movl RCX(%rsp),%ecx
movl RDX(%rsp),%edx
movl RSI(%rsp),%esi
movl RDI(%rsp),%edi
movl %eax,%eax /* zero extension */
.endm
#ifdef CONFIG_PARAVIRT
ENTRY(native_usergs_sysret32)
swapgs
@ -269,7 +247,14 @@ sysenter_tracesys:
movq %rax, R8(%rsp)
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 /* reload args from stack in case ptrace changed it */
/* Reload arg registers from stack. (see sysenter_tracesys) */
movl RCX(%rsp), %ecx
movl RDX(%rsp), %edx
movl RSI(%rsp), %esi
movl RDI(%rsp), %edi
movl %eax, %eax /* zero extension */
RESTORE_EXTRA_REGS
jmp sysenter_do_call
ENDPROC(ia32_sysenter_target)
@ -413,7 +398,15 @@ cstar_tracesys:
movq %rax, R8(%rsp)
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 1 /* reload args from stack in case ptrace changed it */
movl R9(%rsp),%r9d
/* Reload arg registers from stack. (see sysenter_tracesys) */
movl RCX(%rsp), %ecx
movl RDX(%rsp), %edx
movl RSI(%rsp), %esi
movl RDI(%rsp), %edi
movl %eax, %eax /* zero extension */
RESTORE_EXTRA_REGS
xchgl %ebp,%r9d
jmp cstar_do_call
@ -502,7 +495,18 @@ ia32_tracesys:
SAVE_EXTRA_REGS
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 /* reload args from stack in case ptrace changed it */
/*
* Reload arg registers from stack in case ptrace changed them.
* Don't reload %eax because syscall_trace_enter() returned
* the %rax value we should see. But do truncate it to 32 bits.
* If it's -1 to make us punt the syscall, then (u32)-1 is still
* an appropriately invalid value.
*/
movl RCX(%rsp), %ecx
movl RDX(%rsp), %edx
movl RSI(%rsp), %esi
movl RDI(%rsp), %edi
movl %eax, %eax /* zero extension */
RESTORE_EXTRA_REGS
jmp ia32_do_call
END(ia32_syscall)