From 783faefab8d8c5eadc6e3538999b0a407617998d Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 29 Dec 2003 05:44:18 -0800 Subject: [PATCH] [PATCH] Fix sysenter disabling in vm86 mode From: Brian Gerst The current code disables sysenter when first entering vm86 mode, but does not disable it again when coming back to a vm86 task after a task switch. --- arch/i386/kernel/cpu/common.c | 2 +- arch/i386/kernel/process.c | 2 +- arch/i386/kernel/vm86.c | 9 ++++++--- include/asm-i386/processor.h | 20 +++++++------------- 4 files changed, 15 insertions(+), 18 deletions(-) diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c index 17b0c008793cf..6dac129171bad 100644 --- a/arch/i386/kernel/cpu/common.c +++ b/arch/i386/kernel/cpu/common.c @@ -510,7 +510,7 @@ void __init cpu_init (void) BUG(); enter_lazy_tlb(&init_mm, current); - load_esp0(t, thread->esp0); + load_esp0(t, thread); set_tss_desc(cpu,t); cpu_gdt_table[cpu][GDT_ENTRY_TSS].b &= 0xfffffdff; load_TR_desc(); diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index b706916eccc61..6bb3b058ffc13 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -507,7 +507,7 @@ struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct /* * Reload esp0, LDT and the page table pointer: */ - load_esp0(tss, next->esp0); + load_esp0(tss, next); /* * Load the per-thread Thread-Local Storage descriptor. diff --git a/arch/i386/kernel/vm86.c b/arch/i386/kernel/vm86.c index 4c893a9342742..3fb0b829b3f56 100644 --- a/arch/i386/kernel/vm86.c +++ b/arch/i386/kernel/vm86.c @@ -124,7 +124,8 @@ struct pt_regs * save_v86_state(struct kernel_vm86_regs * regs) tss = init_tss + get_cpu(); current->thread.esp0 = current->thread.saved_esp0; - load_esp0(tss, current->thread.esp0); + current->thread.sysenter_cs = __KERNEL_CS; + load_esp0(tss, ¤t->thread); current->thread.saved_esp0 = 0; put_cpu(); @@ -301,8 +302,10 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk asm volatile("movl %%gs,%0":"=m" (tsk->thread.saved_gs)); tss = init_tss + get_cpu(); - tss->esp0 = tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0; - disable_sysenter(tss); + tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0; + if (cpu_has_sep) + tsk->thread.sysenter_cs = 0; + load_esp0(tss, &tsk->thread); put_cpu(); tsk->thread.screen_bitmap = info->screen_bitmap; diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index b9998ad132679..553404457974e 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -407,6 +407,7 @@ struct thread_struct { /* cached TLS descriptors. */ struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES]; unsigned long esp0; + unsigned long sysenter_cs; unsigned long eip; unsigned long esp; unsigned long fs; @@ -428,6 +429,7 @@ struct thread_struct { #define INIT_THREAD { \ .vm86_info = NULL, \ + .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ } @@ -447,21 +449,13 @@ struct thread_struct { .io_bitmap = { [ 0 ... IO_BITMAP_LONGS] = ~0 }, \ } -static inline void load_esp0(struct tss_struct *tss, unsigned long esp0) +static inline void load_esp0(struct tss_struct *tss, struct thread_struct *thread) { - tss->esp0 = esp0; + tss->esp0 = thread->esp0; /* This can only happen when SEP is enabled, no need to test "SEP"arately */ - if ((unlikely(tss->ss1 != __KERNEL_CS))) { - tss->ss1 = __KERNEL_CS; - wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); - } -} - -static inline void disable_sysenter(struct tss_struct *tss) -{ - if (cpu_has_sep) { - tss->ss1 = 0; - wrmsr(MSR_IA32_SYSENTER_CS, 0, 0); + if (unlikely(tss->ss1 != thread->sysenter_cs)) { + tss->ss1 = thread->sysenter_cs; + wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0); } } -- 2.53.0