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Date: Sun, 26 Jul 2015 16:29:10 -0700 From: Andy Lutomirski <luto@...nel.org> To: X86 ML <x86@...nel.org>, "xen-devel@...ts.xen.org" <xen-devel@...ts.xen.org>, Andrew Cooper <andrew.cooper3@...rix.com> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...en8.de>, Steven Rostedt <rostedt@...dmis.org>, Andy Lutomirski <luto@...nel.org> Subject: [PATCH 2/2] 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. Signed-off-by: Andy Lutomirski <luto@...nel.org> --- arch/x86/entry/entry_64.S | 9 +-------- arch/x86/entry/entry_64_compat.S | 2 +- arch/x86/xen/xen-asm_64.S | 24 ++++++++++-------------- 3 files changed, 12 insertions(+), 23 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f47996910331..ebe7e2ca19fe 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -134,14 +134,7 @@ ENTRY(entry_SYSCALL_64) * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON, * it is too small to ever cause noticeable irq latency. */ - SWAPGS_UNSAFE_STACK - /* - * A hypervisor implementation might want to use a label - * after the swapgs, so that it can do the swapgs - * for the guest and jump here on syscall. - */ -GLOBAL(entry_SYSCALL_64_after_swapgs) - + swapgs movq %rsp, PER_CPU_VAR(rsp_scratch) movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index d39495d6446e..beae2b75b588 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -309,7 +309,7 @@ ENTRY(entry_SYSCALL_compat) * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON, * it is too small to ever cause noticeable irq latency. */ - SWAPGS_UNSAFE_STACK + swapgs movl %esp, %r8d movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index f22667abf7b9..c2b5868a9967 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -100,34 +100,30 @@ RELOC(xen_sysret32, 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 + movl (3*8)(%rsp), %r8d /* r8d = user esp */ + jmp entry_SYSCALL_compat_after_hwframe_esp_in_r8d 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) -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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