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| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-03-09 18:39:23 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-10 12:56:10 (GMT) |
| commit | 263042e4630a85e856b4a8cd72f28dab33ef4741 (patch) | |
| tree | 268f16dc93d2f111ffd484300042df3bb089e050 /arch/x86/kernel/entry_64.S | |
| parent | 616ab249f1e42f6135642183529f910fcedc2642 (diff) | |
| download | linux-263042e4630a85e856b4a8cd72f28dab33ef4741.tar.xz | |
x86/asm/entry/64: Save user RSP in pt_regs->sp on SYSCALL64 fastpath
Prepare for the removal of 'usersp', by simplifying PER_CPU(old_rsp) usage:
- use it only as temp storage
- store the userspace stack pointer immediately in pt_regs->sp
on syscall entry, instead of using it later, on syscall exit.
- change C code to use pt_regs->sp only, instead of PER_CPU(old_rsp)
and task->thread.usersp.
FIXUP/RESTORE_TOP_OF_STACK are simplified as well.
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/1425926364-9526-4-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.S | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 703ced0..d86788c 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -128,8 +128,6 @@ ENDPROC(native_usergs_sysret64) * manipulation. */ .macro FIXUP_TOP_OF_STACK tmp offset=0 - movq PER_CPU_VAR(old_rsp),\tmp - movq \tmp,RSP+\offset(%rsp) movq $__USER_DS,SS+\offset(%rsp) movq $__USER_CS,CS+\offset(%rsp) movq RIP+\offset(%rsp),\tmp /* get rip */ @@ -139,8 +137,7 @@ ENDPROC(native_usergs_sysret64) .endm .macro RESTORE_TOP_OF_STACK tmp offset=0 - movq RSP+\offset(%rsp),\tmp - movq \tmp,PER_CPU_VAR(old_rsp) + /* nothing to do */ .endm /* @@ -222,9 +219,6 @@ ENDPROC(native_usergs_sysret64) * Interrupts are off on entry. * Only called from user space. * - * XXX if we had a free scratch register we could save the RSP into the stack frame - * and report it properly in ps. Unfortunately we haven't. - * * When user can change the frames always force IRET. That is because * it deals with uncanonical addresses better. SYSRET has trouble * with them due to bugs in both AMD and Intel CPUs. @@ -253,11 +247,13 @@ GLOBAL(system_call_after_swapgs) */ ENABLE_INTERRUPTS(CLBR_NONE) ALLOC_PT_GPREGS_ON_STACK 8 /* +8: space for orig_ax */ + movq %rcx,RIP(%rsp) + movq PER_CPU_VAR(old_rsp),%rcx + movq %r11,EFLAGS(%rsp) + movq %rcx,RSP(%rsp) + movq_cfi rax,ORIG_RAX SAVE_C_REGS_EXCEPT_RAX_RCX_R11 movq $-ENOSYS,RAX(%rsp) - movq_cfi rax,ORIG_RAX - movq %r11,EFLAGS(%rsp) - movq %rcx,RIP(%rsp) CFI_REL_OFFSET rip,RIP testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP) jnz tracesys @@ -293,7 +289,7 @@ ret_from_sys_call: CFI_REGISTER rip,rcx movq EFLAGS(%rsp),%r11 /*CFI_REGISTER rflags,r11*/ - movq PER_CPU_VAR(old_rsp), %rsp + movq RSP(%rsp),%rsp /* * 64bit SYSRET restores rip from rcx, * rflags from r11 (but RF and VM bits are forced to 0), |