Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Mon, 27 Oct 2003 12:41:05 -0500 | From | Brian Gerst <> | Subject | [PATCH] Fix sysenter disabling in vm86 mode |
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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.
-- Brian Gerst diff -urN linux-2.6.0-test8-bk/arch/i386/kernel/cpu/common.c linux/arch/i386/kernel/cpu/common.c --- linux-2.6.0-test8-bk/arch/i386/kernel/cpu/common.c 2003-09-28 10:20:31.000000000 -0400 +++ linux/arch/i386/kernel/cpu/common.c 2003-10-22 10:10:39.932356584 -0400 @@ -510,7 +510,7 @@ 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 -urN linux-2.6.0-test8-bk/arch/i386/kernel/process.c linux/arch/i386/kernel/process.c --- linux-2.6.0-test8-bk/arch/i386/kernel/process.c 2003-10-08 16:11:44.000000000 -0400 +++ linux/arch/i386/kernel/process.c 2003-10-22 10:10:39.933356432 -0400 @@ -507,7 +507,7 @@ /* * 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 -urN linux-2.6.0-test8-bk/arch/i386/kernel/vm86.c linux/arch/i386/kernel/vm86.c --- linux-2.6.0-test8-bk/arch/i386/kernel/vm86.c 2003-07-27 12:57:40.000000000 -0400 +++ linux/arch/i386/kernel/vm86.c 2003-10-22 10:10:39.934356280 -0400 @@ -117,7 +117,8 @@ 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(); @@ -294,8 +295,10 @@ 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 -urN linux-2.6.0-test8-bk/include/asm-i386/processor.h linux/include/asm-i386/processor.h --- linux-2.6.0-test8-bk/include/asm-i386/processor.h 2003-10-18 09:29:32.000000000 -0400 +++ linux/include/asm-i386/processor.h 2003-10-22 10:10:50.824700696 -0400 @@ -407,6 +407,7 @@ /* 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 @@ #define INIT_THREAD { \ .vm86_info = NULL, \ + .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ } @@ -447,21 +449,13 @@ .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); } } | ![\](/images/icornerr.gif) |