diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2008-06-25 06:19:30 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-08 13:15:56 +0200 |
| commit | a00394f81f419beb6fb9f7023bd4d15913dc625d (patch) | |
| tree | 0faef5a52c4244173a3669bc646ef12bb79d6bc6 /include/asm-x86/paravirt.h | |
| parent | x86, 64-bit: ia32entry: replace privileged instructions with pvops (diff) | |
| download | linux-a00394f81f419beb6fb9f7023bd4d15913dc625d.tar.xz linux-a00394f81f419beb6fb9f7023bd4d15913dc625d.zip | |
x86, 64-bit: swapgs pvop with a user-stack can never be called
It's never safe to call a swapgs pvop when the user stack is current -
it must be inline replaced. Rather than making a call, the
SWAPGS_UNSAFE_STACK pvop always just puts "swapgs" as a placeholder,
which must either be replaced inline or trap'n'emulated (somehow).
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/asm-x86/paravirt.h')
| -rw-r--r-- | include/asm-x86/paravirt.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h index 33f72f8fe757..3286a0c63b42 100644 --- a/include/asm-x86/paravirt.h +++ b/include/asm-x86/paravirt.h @@ -1522,6 +1522,16 @@ static inline unsigned long __raw_local_irq_save(void) #else /* !CONFIG_X86_32 */ + +/* + * If swapgs is used while the userspace stack is still current, + * there's no way to call a pvop. The PV replacement *must* be + * inlined, or the swapgs instruction must be trapped and emulated. + */ +#define SWAPGS_UNSAFE_STACK \ + PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_swapgs), CLBR_NONE, \ + swapgs) + #define SWAPGS \ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_swapgs), CLBR_NONE, \ PV_SAVE_REGS; \ |