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| author | Andy Lutomirski <luto@kernel.org> | 2017-08-08 06:59:21 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-08-10 14:14:32 +0300 |
| commit | 8a9949bc71a71b3dd633255ebe8f8869b1f73474 (patch) | |
| tree | 92ae84676be102ef6fee29bc03457de6450cef1f /arch/x86/xen | |
| parent | 1d0f49e14007a5426eb7e9e5808168cdb77b3e7f (diff) | |
| download | linux-8a9949bc71a71b3dd633255ebe8f8869b1f73474.tar.xz | |
x86/xen/64: Rearrange the SYSCALL entries
Xen's raw SYSCALL entries are much less weird than native. Rather
than fudging them to look like native entries, use the Xen-provided
stack frame directly.
This lets us eliminate entry_SYSCALL_64_after_swapgs and two uses of
the SWAPGS_UNSAFE_STACK paravirt hook. The SYSENTER code would
benefit from similar treatment.
This makes one change to the native code path: the compat
instruction that clears the high 32 bits of %rax is moved slightly
later. I'd be surprised if this affects performance at all.
Tested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/7c88ed36805d36841ab03ec3b48b4122c4418d71.1502164668.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/xen')
| -rw-r--r-- | arch/x86/xen/xen-asm_64.S | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index c3df43141e70..a8a4f4c460a6 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -82,34 +82,29 @@ RELOC(xen_sysret64, 1b+1) * rip * r11 * rsp->rcx - * - * In all the entrypoints, we undo all that to make it look like a - * CPU-generated syscall/sysenter and jump to the normal entrypoint. */ -.macro undo_xen_syscall - mov 0*8(%rsp), %rcx - mov 1*8(%rsp), %r11 - mov 5*8(%rsp), %rsp -.endm - /* Normal 64-bit system call target */ ENTRY(xen_syscall_target) - undo_xen_syscall - jmp entry_SYSCALL_64_after_swapgs + popq %rcx + popq %r11 + jmp entry_SYSCALL_64_after_hwframe ENDPROC(xen_syscall_target) #ifdef CONFIG_IA32_EMULATION /* 32-bit compat syscall target */ ENTRY(xen_syscall32_target) - undo_xen_syscall - jmp entry_SYSCALL_compat + popq %rcx + popq %r11 + jmp entry_SYSCALL_compat_after_hwframe ENDPROC(xen_syscall32_target) /* 32-bit compat sysenter target */ ENTRY(xen_sysenter_target) - undo_xen_syscall + mov 0*8(%rsp), %rcx + mov 1*8(%rsp), %r11 + mov 5*8(%rsp), %rsp jmp entry_SYSENTER_compat ENDPROC(xen_sysenter_target) |