Messages in this thread |  | | Date | Wed, 17 Oct 2012 17:03:09 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 1/4] x86/wakeup/sleep: Check whether the TSS GDT descriptor is empty before using it. |
| |
On 10/17/2012 06:49 AM, Konrad Rzeszutek Wilk wrote: > We check the TSS descriptor before we try to dereference it. > Also fix up the value to use the #defines. > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > --- > arch/x86/power/cpu.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c > index 218cdb1..c17370e 100644 > --- a/arch/x86/power/cpu.c > +++ b/arch/x86/power/cpu.c > @@ -133,7 +133,9 @@ static void fix_processor_context(void) > { > int cpu = smp_processor_id(); > struct tss_struct *t = &per_cpu(init_tss, cpu); > - > +#ifdef CONFIG_X86_64 > + struct desc_struct *desc = get_cpu_gdt_table(cpu); > +#endif > set_tss_desc(cpu, t); /* > * This just modifies memory; should not be > * necessary. But... This is necessary, because > @@ -142,7 +144,8 @@ static void fix_processor_context(void) > */ > > #ifdef CONFIG_X86_64 > - get_cpu_gdt_table(cpu)[GDT_ENTRY_TSS].type = 9; > + if (!desc_empty(&desc[GDT_ENTRY_TSS])) > + desc[GDT_ENTRY_TSS].type = DESC_TSS; > > syscall_init(); /* This sets MSR_*STAR and related */ > #endif >
Why is this patch necessary? Presumably there is something further down the line which depends on the TSS descriptor being empty, but if so, what?
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
|  |