[PATCH 1/2] x86_64: add pseudo-features for 32-bit compat syscall

[PATCH 1/2] x86_64: add pseudo-features for 32-bit compat syscall

[Jeremy Fitzhardinge]

Add pseudo-feature bits to describe whether the CPU supports sysenter
and/or syscall from ia32-compat userspace.  This removes a hardcoded
test in vdso32-setup.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/kernel/cpu/centaur_64.c |    2 ++
 arch/x86/kernel/cpu/common_64.c  |    3 +++
 arch/x86/kernel/cpu/intel_64.c   |    2 ++
 include/asm-x86/cpufeature.h     |    4 ++--
 4 files changed, 9 insertions(+), 2 deletions(-)

===================================================================
--- a/arch/x86/kernel/cpu/centaur_64.c
+++ b/arch/x86/kernel/cpu/centaur_64.c
@@ -10,6 +10,8 @@ static void __cpuinit early_init_centaur
 {
 	if (c->x86 == 0x6 && c->x86_model >= 0xf)
 		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
+
+	set_cpu_cap(c, X86_FEATURE_SYSENTER32);
 }
 
 static void __cpuinit init_centaur(struct cpuinfo_x86 *c)
===================================================================
--- a/arch/x86/kernel/cpu/common_64.c
+++ b/arch/x86/kernel/cpu/common_64.c
@@ -315,6 +315,9 @@ static void __cpuinit early_identify_cpu
 	if (c->extended_cpuid_level >= 0x80000007)
 		c->x86_power = cpuid_edx(0x80000007);
 
+	/* Assume all 64-bit CPUs support 32-bit syscall */
+	set_cpu_cap(c, X86_FEATURE_SYSCALL32);
+
 	if (c->x86_vendor != X86_VENDOR_UNKNOWN &&
 	    cpu_devs[c->x86_vendor]->c_early_init)
 		cpu_devs[c->x86_vendor]->c_early_init(c);
===================================================================
--- a/arch/x86/kernel/cpu/intel_64.c
+++ b/arch/x86/kernel/cpu/intel_64.c
@@ -12,6 +12,8 @@ static void __cpuinit early_init_intel(s
 	if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
 	    (c->x86 == 0x6 && c->x86_model >= 0x0e))
 		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
+
+	set_cpu_cap(c, X86_FEATURE_SYSENTER32);
 }
 
 /*
===================================================================
--- a/include/asm-x86/cpufeature.h
+++ b/include/asm-x86/cpufeature.h
@@ -74,8 +74,8 @@
 #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */
 #define X86_FEATURE_PEBS	(3*32+12)  /* Precise-Event Based Sampling */
 #define X86_FEATURE_BTS		(3*32+13)  /* Branch Trace Store */
-/* 14 free */
-/* 15 free */
+#define X86_FEATURE_SYSCALL32	(3*32+14)  /* syscall in ia32 userspace */
+#define X86_FEATURE_SYSENTER32	(3*32+15)  /* sysenter in ia32 userspace */
 #define X86_FEATURE_REP_GOOD	(3*32+16) /* rep microcode works well on this CPU */
 #define X86_FEATURE_MFENCE_RDTSC (3*32+17) /* Mfence synchronizes RDTSC */
 #define X86_FEATURE_LFENCE_RDTSC (3*32+18) /* Lfence synchronizes RDTSC */

[PATCH 1a/2] x86_64: vdso32 cleanup using feature flags

[Jeremy Fitzhardinge]

Use the X86_FEATURE_SYSENTER32 to remove hard-coded CPU vendor check.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/vdso/vdso32-setup.c |   11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

===================================================================
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -203,20 +203,11 @@ static struct page *vdso32_pages[1];
 
 #ifdef CONFIG_X86_64
 
-static int use_sysenter __read_mostly = -1;
-
-#define	vdso32_sysenter()	(use_sysenter > 0)
+#define	vdso32_sysenter()	(boot_cpu_has(X86_FEATURE_SYSENTER32))
 
 /* May not be __init: called during resume */
 void syscall32_cpu_init(void)
 {
-	if (use_sysenter < 0) {
-		if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
-			use_sysenter = 1;
-		if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR)
-			use_sysenter = 1;
-	}
-
 	/* Load these always in case some future AMD CPU supports
 	   SYSENTER from compat mode too. */
 	checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);

Re: [PATCH 1a/2] x86_64: vdso32 cleanup using feature flags

[Ingo Molnar]

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Use the X86_FEATURE_SYSENTER32 to remove hard-coded CPU vendor check.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

nice cleanup - applied these two to tip/x86/core.

	Ingo