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SubjectRe: [Xen-devel] Re: [PATCH] xen: Disable stack protector for irq helper
On 10/12/09 13:52, Ingo Molnar wrote:
> ping - any update about this fix? Since it fixes a real crash it would
> be nice to fix this for .32.
>

The following changes since commit 2caa731819a633bec5a56736e64c562b7e193666:
Linus Torvalds (1):
Merge branch 'for-linus' of git://git.kernel.org/.../jbarnes/pci-2.6

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git mainline/x86-paravirt-fix

Jeremy Fitzhardinge (1):
x86/paravirt: use normal calling sequences for irq enable/disable etc

arch/x86/include/asm/paravirt.h | 28 ++++------------------------
arch/x86/include/asm/paravirt_types.h | 10 ++++++----
2 files changed, 10 insertions(+), 28 deletions(-)

Subject: [PATCH] x86/paravirt: use normal calling sequences for irq enable/disable etc

For historical reasons irq enable/disable/save/restore had special
calling sequences to make them more efficient. With the more
recent introduction of higher-level and more general optimisations
this is no longer necessary so we can just use the normal PVOP_
macros. This fixes some residual bugs in the old implementations which
left edx liable to inadvertent clobbering.

Also, fix some bugs in __PVOP_VCALLEESAVE which were revealed by actual
use.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 8aebcc4..efb3899 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -840,42 +840,22 @@ static __always_inline void __raw_spin_unlock(struct raw_spinlock *lock)

static inline unsigned long __raw_local_save_flags(void)
{
- unsigned long f;
-
- asm volatile(paravirt_alt(PARAVIRT_CALL)
- : "=a"(f)
- : paravirt_type(pv_irq_ops.save_fl),
- paravirt_clobber(CLBR_EAX)
- : "memory", "cc");
- return f;
+ return PVOP_CALLEE0(unsigned long, pv_irq_ops.save_fl);
}

static inline void raw_local_irq_restore(unsigned long f)
{
- asm volatile(paravirt_alt(PARAVIRT_CALL)
- : "=a"(f)
- : PV_FLAGS_ARG(f),
- paravirt_type(pv_irq_ops.restore_fl),
- paravirt_clobber(CLBR_EAX)
- : "memory", "cc");
+ PVOP_VCALLEE1(pv_irq_ops.restore_fl, f);
}

static inline void raw_local_irq_disable(void)
{
- asm volatile(paravirt_alt(PARAVIRT_CALL)
- :
- : paravirt_type(pv_irq_ops.irq_disable),
- paravirt_clobber(CLBR_EAX)
- : "memory", "eax", "cc");
+ PVOP_VCALLEE0(pv_irq_ops.irq_disable);
}

static inline void raw_local_irq_enable(void)
{
- asm volatile(paravirt_alt(PARAVIRT_CALL)
- :
- : paravirt_type(pv_irq_ops.irq_enable),
- paravirt_clobber(CLBR_EAX)
- : "memory", "eax", "cc");
+ PVOP_VCALLEE0(pv_irq_ops.irq_enable);
}

static inline unsigned long __raw_local_irq_save(void)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index dd0f5b3..9357473 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -494,10 +494,11 @@ int paravirt_disable_iospace(void);
#define EXTRA_CLOBBERS
#define VEXTRA_CLOBBERS
#else /* CONFIG_X86_64 */
+/* [re]ax isn't an arg, but the return val */
#define PVOP_VCALL_ARGS \
unsigned long __edi = __edi, __esi = __esi, \
- __edx = __edx, __ecx = __ecx
-#define PVOP_CALL_ARGS PVOP_VCALL_ARGS, __eax
+ __edx = __edx, __ecx = __ecx, __eax = __eax
+#define PVOP_CALL_ARGS PVOP_VCALL_ARGS

#define PVOP_CALL_ARG1(x) "D" ((unsigned long)(x))
#define PVOP_CALL_ARG2(x) "S" ((unsigned long)(x))
@@ -509,6 +510,7 @@ int paravirt_disable_iospace(void);
"=c" (__ecx)
#define PVOP_CALL_CLOBBERS PVOP_VCALL_CLOBBERS, "=a" (__eax)

+/* void functions are still allowed [re]ax for scratch */
#define PVOP_VCALLEE_CLOBBERS "=a" (__eax)
#define PVOP_CALLEE_CLOBBERS PVOP_VCALLEE_CLOBBERS

@@ -583,8 +585,8 @@ int paravirt_disable_iospace(void);
VEXTRA_CLOBBERS, \
pre, post, ##__VA_ARGS__)

-#define __PVOP_VCALLEESAVE(rettype, op, pre, post, ...) \
- ____PVOP_CALL(rettype, op.func, CLBR_RET_REG, \
+#define __PVOP_VCALLEESAVE(op, pre, post, ...) \
+ ____PVOP_VCALL(op.func, CLBR_RET_REG, \
PVOP_VCALLEE_CLOBBERS, , \
pre, post, ##__VA_ARGS__)



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