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Message-ID: <CALCETrVMyd-Hh4uxJQrDbV6+JPSg_RtFK49H+XkE1eBG+9-J_w@mail.gmail.com>
Date: Tue, 21 Apr 2015 11:56:39 -0700
From: Andy Lutomirski <luto@...capital.net>
To: Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.org>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
X86 ML <x86@...nel.org>,
Denys Vlasenko <vda.linux@...glemail.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Denys Vlasenko <dvlasenk@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH] x86, paravirt, xen: Remove the 64-bit irq_enable_sysexit pvop
On Fri, Apr 3, 2015 at 3:51 PM, Andy Lutomirski <luto@...nel.org> wrote:
> We don't use irq_enable_sysexit on 64-bit kernels any more. Remove
> all the paravirt and Xen machinery to support it on 64-bit kernels.
>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
Hi, Ingo,
Can you pick this up in -tip? It cleans up code that would otherwise
be unreachable in 4.1, but it doesn't fix any bugs, so waiting for 4.2
would be fine as well.
--Andy
> ---
>
> I haven't actually tested this on Xen, but it builds for me.
>
> arch/x86/ia32/ia32entry.S | 6 ------
> arch/x86/include/asm/paravirt_types.h | 7 ++++---
> arch/x86/kernel/asm-offsets.c | 2 ++
> arch/x86/kernel/paravirt.c | 4 +++-
> arch/x86/kernel/paravirt_patch_64.c | 1 -
> arch/x86/xen/enlighten.c | 3 ++-
> arch/x86/xen/xen-asm_64.S | 16 ----------------
> arch/x86/xen/xen-ops.h | 2 ++
> 8 files changed, 13 insertions(+), 28 deletions(-)
>
> diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
> index 5d8f987a340d..eb1eb7b70f4b 100644
> --- a/arch/x86/ia32/ia32entry.S
> +++ b/arch/x86/ia32/ia32entry.S
> @@ -77,12 +77,6 @@ ENTRY(native_usergs_sysret32)
> swapgs
> sysretl
> ENDPROC(native_usergs_sysret32)
> -
> -ENTRY(native_irq_enable_sysexit)
> - swapgs
> - sti
> - sysexit
> -ENDPROC(native_irq_enable_sysexit)
> #endif
>
> /*
> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
> index 7549b8b369e4..38a0ff9ef06e 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -160,13 +160,14 @@ struct pv_cpu_ops {
> u64 (*read_pmc)(int counter);
> unsigned long long (*read_tscp)(unsigned int *aux);
>
> +#ifdef CONFIG_X86_32
> /*
> * Atomically enable interrupts and return to userspace. This
> - * is only ever used to return to 32-bit processes; in a
> - * 64-bit kernel, it's used for 32-on-64 compat processes, but
> - * never native 64-bit processes. (Jump, not call.)
> + * is only used in 32-bit kernels. 64-bit kernels use
> + * usergs_sysret32 instead.
> */
> void (*irq_enable_sysexit)(void);
> +#endif
>
> /*
> * Switch to usermode gs and return to 64-bit usermode using
> diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
> index 9f6b9341950f..2d27ebf0aed8 100644
> --- a/arch/x86/kernel/asm-offsets.c
> +++ b/arch/x86/kernel/asm-offsets.c
> @@ -49,7 +49,9 @@ void common(void) {
> OFFSET(PV_IRQ_irq_disable, pv_irq_ops, irq_disable);
> OFFSET(PV_IRQ_irq_enable, pv_irq_ops, irq_enable);
> OFFSET(PV_CPU_iret, pv_cpu_ops, iret);
> +#ifdef CONFIG_X86_32
> OFFSET(PV_CPU_irq_enable_sysexit, pv_cpu_ops, irq_enable_sysexit);
> +#endif
> OFFSET(PV_CPU_read_cr0, pv_cpu_ops, read_cr0);
> OFFSET(PV_MMU_read_cr2, pv_mmu_ops, read_cr2);
> #endif
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index 548d25f00c90..7563114d9c3a 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -154,7 +154,9 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
> ret = paravirt_patch_ident_64(insnbuf, len);
>
> else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
> +#ifdef CONFIG_X86_32
> type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
> +#endif
> type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
> type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
> /* If operation requires a jmp, then jmp */
> @@ -371,7 +373,7 @@ __visible struct pv_cpu_ops pv_cpu_ops = {
>
> .load_sp0 = native_load_sp0,
>
> -#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
> +#if defined(CONFIG_X86_32)
> .irq_enable_sysexit = native_irq_enable_sysexit,
> #endif
> #ifdef CONFIG_X86_64
> diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
> index a1da6737ba5b..0de21c62c348 100644
> --- a/arch/x86/kernel/paravirt_patch_64.c
> +++ b/arch/x86/kernel/paravirt_patch_64.c
> @@ -49,7 +49,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
> PATCH_SITE(pv_irq_ops, save_fl);
> PATCH_SITE(pv_irq_ops, irq_enable);
> PATCH_SITE(pv_irq_ops, irq_disable);
> - PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
> PATCH_SITE(pv_cpu_ops, usergs_sysret32);
> PATCH_SITE(pv_cpu_ops, usergs_sysret64);
> PATCH_SITE(pv_cpu_ops, swapgs);
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 81665c9f2132..3797b6b31f95 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1267,10 +1267,11 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
> .read_tscp = native_read_tscp,
>
> .iret = xen_iret,
> - .irq_enable_sysexit = xen_sysexit,
> #ifdef CONFIG_X86_64
> .usergs_sysret32 = xen_sysret32,
> .usergs_sysret64 = xen_sysret64,
> +#else
> + .irq_enable_sysexit = xen_sysexit,
> #endif
>
> .load_tr_desc = paravirt_nop,
> diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
> index 985fc3ee0973..a2cabb8bd6bf 100644
> --- a/arch/x86/xen/xen-asm_64.S
> +++ b/arch/x86/xen/xen-asm_64.S
> @@ -47,22 +47,6 @@ ENTRY(xen_iret)
> ENDPATCH(xen_iret)
> RELOC(xen_iret, 1b+1)
>
> -/*
> - * sysexit is not used for 64-bit processes, so it's only ever used to
> - * return to 32-bit compat userspace.
> - */
> -ENTRY(xen_sysexit)
> - pushq $__USER32_DS
> - pushq %rcx
> - pushq $X86_EFLAGS_IF
> - pushq $__USER32_CS
> - pushq %rdx
> -
> - pushq $0
> -1: jmp hypercall_iret
> -ENDPATCH(xen_sysexit)
> -RELOC(xen_sysexit, 1b+1)
> -
> ENTRY(xen_sysret64)
> /*
> * We're already on the usermode stack at this point, but
> diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
> index 9e195c683549..c20fe29e65f4 100644
> --- a/arch/x86/xen/xen-ops.h
> +++ b/arch/x86/xen/xen-ops.h
> @@ -134,7 +134,9 @@ DECL_ASM(void, xen_restore_fl_direct, unsigned long);
>
> /* These are not functions, and cannot be called normally */
> __visible void xen_iret(void);
> +#ifdef CONFIG_X86_32
> __visible void xen_sysexit(void);
> +#endif
> __visible void xen_sysret32(void);
> __visible void xen_sysret64(void);
> __visible void xen_adjust_exception_frame(void);
> --
> 2.3.0
>
--
Andy Lutomirski
AMA Capital Management, LLC
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