From d75cd22fdd5f7d203fb60014d426942df33dd9a6 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 25 Jun 2008 00:19:26 -0400 Subject: [PATCH] x86/paravirt: split sysret and sysexit Don't conflate sysret and sysexit; they're different instructions with different semantics, and may be in use at the same time (at least within the same kernel, depending on whether its an Intel or AMD system). sysexit - just return to userspace, does no register restoration of any kind; must explicitly atomically enable interrupts. sysret - reloads flags from r11, so no need to explicitly enable interrupts on 64-bit, responsible for restoring usermode %gs Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- arch/x86/kernel/asm-offsets_32.c | 2 +- arch/x86/kernel/asm-offsets_64.c | 2 +- arch/x86/kernel/entry_32.S | 8 ++++---- arch/x86/kernel/entry_64.S | 4 ++-- arch/x86/kernel/paravirt.c | 12 +++++++++--- arch/x86/kernel/paravirt_patch_32.c | 4 ++-- arch/x86/kernel/paravirt_patch_64.c | 4 ++-- arch/x86/kernel/vmi_32.c | 4 ++-- arch/x86/xen/enlighten.c | 2 +- include/asm-x86/irqflags.h | 4 ++-- include/asm-x86/paravirt.h | 15 ++++++++++----- 11 files changed, 36 insertions(+), 25 deletions(-) diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index 9258808..6649d09 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -111,7 +111,7 @@ void foo(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); - OFFSET(PV_CPU_irq_enable_syscall_ret, pv_cpu_ops, irq_enable_syscall_ret); + OFFSET(PV_CPU_irq_enable_sysexit, pv_cpu_ops, irq_enable_sysexit); OFFSET(PV_CPU_read_cr0, pv_cpu_ops, read_cr0); #endif diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index f126c05..27ac2de 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -62,7 +62,7 @@ int main(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); - OFFSET(PV_CPU_irq_enable_syscall_ret, pv_cpu_ops, irq_enable_syscall_ret); + OFFSET(PV_CPU_usersp_sysret, pv_cpu_ops, usersp_sysret); OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs); OFFSET(PV_MMU_read_cr2, pv_mmu_ops, read_cr2); #endif diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 159a1c7..53393c3 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -58,7 +58,7 @@ * for paravirtualization. The following will never clobber any registers: * INTERRUPT_RETURN (aka. "iret") * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax") - * ENABLE_INTERRUPTS_SYSCALL_RET (aka "sti; sysexit"). + * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit"). * * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY). @@ -349,7 +349,7 @@ sysenter_past_esp: xorl %ebp,%ebp TRACE_IRQS_ON 1: mov PT_FS(%esp), %fs - ENABLE_INTERRUPTS_SYSCALL_RET + ENABLE_INTERRUPTS_SYSEXIT CFI_ENDPROC .pushsection .fixup,"ax" 2: movl $0,PT_FS(%esp) @@ -874,10 +874,10 @@ ENTRY(native_iret) .previous END(native_iret) -ENTRY(native_irq_enable_syscall_ret) +ENTRY(native_irq_enable_sysexit) sti sysexit -END(native_irq_enable_syscall_ret) +END(native_irq_enable_sysexit) #endif KPROBE_ENTRY(int3) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 6d11014..0056bc4 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -59,7 +59,7 @@ #endif #ifdef CONFIG_PARAVIRT -ENTRY(native_irq_enable_syscall_ret) +ENTRY(native_usersp_sysret) movq %gs:pda_oldrsp,%rsp swapgs sysretq @@ -275,7 +275,7 @@ sysret_check: CFI_REGISTER rip,rcx RESTORE_ARGS 0,-ARG_SKIP,1 /*CFI_REGISTER rflags,r11*/ - ENABLE_INTERRUPTS_SYSCALL_RET + USERSP_SYSRET CFI_RESTORE_STATE /* Handle reschedules */ diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 78c9a1b..565ee7a 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -140,7 +140,8 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf, /* If the operation is a nop, then nop the callsite */ ret = paravirt_patch_nop(); else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) || - type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_syscall_ret)) + type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) || + type == PARAVIRT_PATCH(pv_cpu_ops.usersp_sysret)) /* If operation requires a jmp, then jmp */ ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len); else @@ -191,7 +192,8 @@ static void native_flush_tlb_single(unsigned long addr) /* These are in entry.S */ extern void native_iret(void); -extern void native_irq_enable_syscall_ret(void); +extern void native_irq_enable_sysexit(void); +extern void native_usersp_sysret(void); static int __init print_banner(void) { @@ -327,7 +329,11 @@ struct pv_cpu_ops pv_cpu_ops = { .write_idt_entry = native_write_idt_entry, .load_sp0 = native_load_sp0, - .irq_enable_syscall_ret = native_irq_enable_syscall_ret, +#ifdef CONFIG_X86_32 + .irq_enable_sysexit = native_irq_enable_sysexit, +#else + .usersp_sysret = native_usersp_sysret, +#endif .iret = native_iret, .swapgs = native_swapgs, diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c index 82fc5fc..5826221 100644 --- a/arch/x86/kernel/paravirt_patch_32.c +++ b/arch/x86/kernel/paravirt_patch_32.c @@ -5,7 +5,7 @@ DEF_NATIVE(pv_irq_ops, irq_enable, "sti"); DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf"); DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax"); DEF_NATIVE(pv_cpu_ops, iret, "iret"); -DEF_NATIVE(pv_cpu_ops, irq_enable_syscall_ret, "sti; sysexit"); +DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "sti; sysexit"); DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax"); DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3"); DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax"); @@ -29,7 +29,7 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, PATCH_SITE(pv_irq_ops, restore_fl); PATCH_SITE(pv_irq_ops, save_fl); PATCH_SITE(pv_cpu_ops, iret); - PATCH_SITE(pv_cpu_ops, irq_enable_syscall_ret); + PATCH_SITE(pv_cpu_ops, irq_enable_sysexit); PATCH_SITE(pv_mmu_ops, read_cr2); PATCH_SITE(pv_mmu_ops, read_cr3); PATCH_SITE(pv_mmu_ops, write_cr3); diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c index 7d904e1..4a17055 100644 --- a/arch/x86/kernel/paravirt_patch_64.c +++ b/arch/x86/kernel/paravirt_patch_64.c @@ -15,7 +15,7 @@ DEF_NATIVE(pv_cpu_ops, clts, "clts"); DEF_NATIVE(pv_cpu_ops, wbinvd, "wbinvd"); /* the three commands give us more control to how to return from a syscall */ -DEF_NATIVE(pv_cpu_ops, irq_enable_syscall_ret, "movq %gs:" __stringify(pda_oldrsp) ", %rsp; swapgs; sysretq;"); +DEF_NATIVE(pv_cpu_ops, usersp_sysret, "movq %gs:" __stringify(pda_oldrsp) ", %rsp; swapgs; sysretq;"); DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs"); unsigned native_patch(u8 type, u16 clobbers, void *ibuf, @@ -35,7 +35,7 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, PATCH_SITE(pv_irq_ops, irq_enable); PATCH_SITE(pv_irq_ops, irq_disable); PATCH_SITE(pv_cpu_ops, iret); - PATCH_SITE(pv_cpu_ops, irq_enable_syscall_ret); + PATCH_SITE(pv_cpu_ops, usersp_sysret); PATCH_SITE(pv_cpu_ops, swapgs); PATCH_SITE(pv_mmu_ops, read_cr2); PATCH_SITE(pv_mmu_ops, read_cr3); diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c index 956f389..946bf13 100644 --- a/arch/x86/kernel/vmi_32.c +++ b/arch/x86/kernel/vmi_32.c @@ -151,7 +151,7 @@ static unsigned vmi_patch(u8 type, u16 clobbers, void *insns, insns, ip); case PARAVIRT_PATCH(pv_cpu_ops.iret): return patch_internal(VMI_CALL_IRET, len, insns, ip); - case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_syscall_ret): + case PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit): return patch_internal(VMI_CALL_SYSEXIT, len, insns, ip); default: break; @@ -896,7 +896,7 @@ static inline int __init activate_vmi(void) * the backend. They are performance critical anyway, so requiring * a patch is not a big problem. */ - pv_cpu_ops.irq_enable_syscall_ret = (void *)0xfeedbab0; + pv_cpu_ops.irq_enable_sysexit = (void *)0xfeedbab0; pv_cpu_ops.iret = (void *)0xbadbab0; #ifdef CONFIG_SMP diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index d62f14e..119c88f 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1089,7 +1089,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = { .read_pmc = native_read_pmc, .iret = xen_iret, - .irq_enable_syscall_ret = xen_sysexit, + .irq_enable_sysexit = xen_sysexit, .load_tr_desc = paravirt_nop, .set_ldt = xen_set_ldt, diff --git a/include/asm-x86/irqflags.h b/include/asm-x86/irqflags.h index c242527..99ee525 100644 --- a/include/asm-x86/irqflags.h +++ b/include/asm-x86/irqflags.h @@ -112,13 +112,13 @@ static inline unsigned long __raw_local_irq_save(void) #ifdef CONFIG_X86_64 #define INTERRUPT_RETURN iretq -#define ENABLE_INTERRUPTS_SYSCALL_RET \ +#define USERSP_SYSRET \ movq %gs:pda_oldrsp, %rsp; \ swapgs; \ sysretq; #else #define INTERRUPT_RETURN iret -#define ENABLE_INTERRUPTS_SYSCALL_RET sti; sysexit +#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit #define GET_CR0_INTO_EAX movl %cr0, %eax #endif diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h index 82cdcde..2668903 100644 --- a/include/asm-x86/paravirt.h +++ b/include/asm-x86/paravirt.h @@ -141,8 +141,9 @@ struct pv_cpu_ops { u64 (*read_pmc)(int counter); unsigned long long (*read_tscp)(unsigned int *aux); - /* These two are jmp to, not actually called. */ - void (*irq_enable_syscall_ret)(void); + /* These three are jmp to, not actually called. */ + void (*irq_enable_sysexit)(void); + void (*usersp_sysret)(void); void (*iret)(void); void (*swapgs)(void); @@ -1480,10 +1481,10 @@ static inline unsigned long __raw_local_irq_save(void) call PARA_INDIRECT(pv_irq_ops+PV_IRQ_irq_enable); \ PV_RESTORE_REGS;) -#define ENABLE_INTERRUPTS_SYSCALL_RET \ - PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_syscall_ret),\ +#define ENABLE_INTERRUPTS_SYSEXIT \ + PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_sysexit), \ CLBR_NONE, \ - jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_syscall_ret)) + jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_sysexit)) #ifdef CONFIG_X86_32 @@ -1504,6 +1505,10 @@ static inline unsigned long __raw_local_irq_save(void) movq %rax, %rcx; \ xorq %rax, %rax; +#define USERSP_SYSRET \ + PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usersp_sysret), \ + CLBR_NONE, \ + jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usersp_sysret)) #endif #endif /* __ASSEMBLY__ */ -- 2.7.4