From: Glauber de Oliveira Costa Date: Wed, 30 Jan 2008 12:32:08 +0000 (+0100) Subject: x86: replace privileged instructions with paravirt macros X-Git-Tag: v2.6.25-rc1~1143^2~471 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=72fe4858544292ad64600765cb78bc02298c6b1c;p=linux-2.6 x86: replace privileged instructions with paravirt macros The assembly code in entry_64.S issues a bunch of privileged instructions, like cli, sti, swapgs, and others. Paravirt guests are forbidden to do so, and we then replace them with macros that will do the right thing. Signed-off-by: Glauber de Oliveira Costa Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index e70f3881d7..bea8474744 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -50,6 +50,7 @@ #include #include #include +#include .code64 @@ -57,6 +58,13 @@ #define retint_kernel retint_restore_args #endif +#ifdef CONFIG_PARAVIRT +ENTRY(native_irq_enable_syscall_ret) + movq %gs:pda_oldrsp,%rsp + swapgs + sysretq +#endif /* CONFIG_PARAVIRT */ + .macro TRACE_IRQS_IRETQ offset=ARGOFFSET #ifdef CONFIG_TRACE_IRQFLAGS @@ -216,14 +224,21 @@ ENTRY(system_call) CFI_DEF_CFA rsp,PDA_STACKOFFSET CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ - swapgs + 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. + */ +ENTRY(system_call_after_swapgs) + movq %rsp,%gs:pda_oldrsp movq %gs:pda_kernelstack,%rsp /* * No need to follow this irqs off/on section - it's straight * and short: */ - sti + ENABLE_INTERRUPTS(CLBR_NONE) SAVE_ARGS 8,1 movq %rax,ORIG_RAX-ARGOFFSET(%rsp) movq %rcx,RIP-ARGOFFSET(%rsp) @@ -246,7 +261,7 @@ ret_from_sys_call: sysret_check: LOCKDEP_SYS_EXIT GET_THREAD_INFO(%rcx) - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF movl threadinfo_flags(%rcx),%edx andl %edi,%edx @@ -260,9 +275,7 @@ sysret_check: CFI_REGISTER rip,rcx RESTORE_ARGS 0,-ARG_SKIP,1 /*CFI_REGISTER rflags,r11*/ - movq %gs:pda_oldrsp,%rsp - swapgs - sysretq + ENABLE_INTERRUPTS_SYSCALL_RET CFI_RESTORE_STATE /* Handle reschedules */ @@ -271,7 +284,7 @@ sysret_careful: bt $TIF_NEED_RESCHED,%edx jnc sysret_signal TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule @@ -282,7 +295,7 @@ sysret_careful: /* Handle a signal */ sysret_signal: TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) testl $_TIF_DO_NOTIFY_MASK,%edx jz 1f @@ -295,7 +308,7 @@ sysret_signal: 1: movl $_TIF_NEED_RESCHED,%edi /* Use IRET because user could have changed frame. This works because ptregscall_common has called FIXUP_TOP_OF_STACK. */ - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp int_with_check @@ -327,7 +340,7 @@ tracesys: */ .globl int_ret_from_sys_call int_ret_from_sys_call: - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF testl $3,CS-ARGOFFSET(%rsp) je retint_restore_args @@ -349,20 +362,20 @@ int_careful: bt $TIF_NEED_RESCHED,%edx jnc int_very_careful TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule popq %rdi CFI_ADJUST_CFA_OFFSET -8 - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp int_with_check /* handle signals and tracing -- both require a full stack frame */ int_very_careful: TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) SAVE_REST /* Check for syscall exit trace */ testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edx @@ -385,7 +398,7 @@ int_signal: 1: movl $_TIF_NEED_RESCHED,%edi int_restore_rest: RESTORE_REST - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp int_with_check CFI_ENDPROC @@ -506,7 +519,7 @@ END(stub_rt_sigreturn) CFI_DEF_CFA_REGISTER rbp testl $3,CS(%rdi) je 1f - swapgs + SWAPGS /* irqcount is used to check if a CPU is already on an interrupt stack or not. While this is essentially redundant with preempt_count it is a little cheaper to use a separate counter in the PDA @@ -527,7 +540,7 @@ ENTRY(common_interrupt) interrupt do_IRQ /* 0(%rsp): oldrsp-ARGOFFSET */ ret_from_intr: - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF decl %gs:pda_irqcount leaveq @@ -556,13 +569,13 @@ retint_swapgs: /* return to user-space */ /* * The iretq could re-enable interrupts: */ - cli + DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_IRETQ - swapgs + SWAPGS jmp restore_args retint_restore_args: /* return to kernel space */ - cli + DISABLE_INTERRUPTS(CLBR_ANY) /* * The iretq could re-enable interrupts: */ @@ -570,10 +583,14 @@ retint_restore_args: /* return to kernel space */ restore_args: RESTORE_ARGS 0,8,0 iret_label: +#ifdef CONFIG_PARAVIRT + INTERRUPT_RETURN +#endif +ENTRY(native_iret) iretq .section __ex_table,"a" - .quad iret_label,bad_iret + .quad native_iret, bad_iret .previous .section .fixup,"ax" /* force a signal here? this matches i386 behaviour */ @@ -581,24 +598,24 @@ iret_label: bad_iret: movq $11,%rdi /* SIGSEGV */ TRACE_IRQS_ON - sti - jmp do_exit - .previous - + ENABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI)) + jmp do_exit + .previous + /* edi: workmask, edx: work */ retint_careful: CFI_RESTORE_STATE bt $TIF_NEED_RESCHED,%edx jnc retint_signal TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) pushq %rdi CFI_ADJUST_CFA_OFFSET 8 call schedule popq %rdi CFI_ADJUST_CFA_OFFSET -8 GET_THREAD_INFO(%rcx) - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF jmp retint_check @@ -606,14 +623,14 @@ retint_signal: testl $_TIF_DO_NOTIFY_MASK,%edx jz retint_swapgs TRACE_IRQS_ON - sti + ENABLE_INTERRUPTS(CLBR_NONE) SAVE_REST movq $-1,ORIG_RAX(%rsp) xorl %esi,%esi # oldset movq %rsp,%rdi # &pt_regs call do_notify_resume RESTORE_REST - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF movl $_TIF_NEED_RESCHED,%edi GET_THREAD_INFO(%rcx) @@ -731,7 +748,7 @@ END(spurious_interrupt) rdmsr testl %edx,%edx js 1f - swapgs + SWAPGS xorl %ebx,%ebx 1: .if \ist @@ -747,7 +764,7 @@ END(spurious_interrupt) .if \ist addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp) .endif - cli + DISABLE_INTERRUPTS(CLBR_NONE) .if \irqtrace TRACE_IRQS_OFF .endif @@ -776,10 +793,10 @@ paranoid_swapgs\trace: .if \trace TRACE_IRQS_IRETQ 0 .endif - swapgs + SWAPGS_UNSAFE_STACK paranoid_restore\trace: RESTORE_ALL 8 - iretq + INTERRUPT_RETURN paranoid_userspace\trace: GET_THREAD_INFO(%rcx) movl threadinfo_flags(%rcx),%ebx @@ -794,11 +811,11 @@ paranoid_userspace\trace: .if \trace TRACE_IRQS_ON .endif - sti + ENABLE_INTERRUPTS(CLBR_NONE) xorl %esi,%esi /* arg2: oldset */ movq %rsp,%rdi /* arg1: &pt_regs */ call do_notify_resume - cli + DISABLE_INTERRUPTS(CLBR_NONE) .if \trace TRACE_IRQS_OFF .endif @@ -807,9 +824,9 @@ paranoid_schedule\trace: .if \trace TRACE_IRQS_ON .endif - sti + ENABLE_INTERRUPTS(CLBR_ANY) call schedule - cli + DISABLE_INTERRUPTS(CLBR_ANY) .if \trace TRACE_IRQS_OFF .endif @@ -862,7 +879,7 @@ KPROBE_ENTRY(error_entry) testl $3,CS(%rsp) je error_kernelspace error_swapgs: - swapgs + SWAPGS error_sti: movq %rdi,RDI(%rsp) CFI_REL_OFFSET rdi,RDI @@ -874,7 +891,7 @@ error_sti: error_exit: movl %ebx,%eax RESTORE_REST - cli + DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF GET_THREAD_INFO(%rcx) testl %eax,%eax @@ -911,12 +928,12 @@ ENTRY(load_gs_index) CFI_STARTPROC pushf CFI_ADJUST_CFA_OFFSET 8 - cli - swapgs + DISABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI)) + SWAPGS gs_change: movl %edi,%gs 2: mfence /* workaround */ - swapgs + SWAPGS popf CFI_ADJUST_CFA_OFFSET -8 ret @@ -930,7 +947,7 @@ ENDPROC(load_gs_index) .section .fixup,"ax" /* running with kernelgs */ bad_gs: - swapgs /* switch back to user gs */ + SWAPGS /* switch back to user gs */ xorl %eax,%eax movl %eax,%gs jmp 2b