diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2025-12-16 13:26:03 -0800 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2026-01-13 16:37:58 -0800 |
| commit | f49ecf5e110ab0ed255ddea5e321689faf4e50e6 (patch) | |
| tree | 74b9f5720872d9e256f22e037f628cdef1e35fae /arch/x86/kernel/cpu | |
| parent | a0636d4c3ad0da0cd6069eb6fef5d2b7d3449378 (diff) | |
x86/cpufeature: Replace X86_FEATURE_SYSENTER32 with X86_FEATURE_SYSFAST32
In most cases, the use of "fast 32-bit system call" depends either on
X86_FEATURE_SEP or X86_FEATURE_SYSENTER32 || X86_FEATURE_SYSCALL32.
However, nearly all the logic for both is identical.
Define X86_FEATURE_SYSFAST32 which indicates that *either* SYSENTER32 or
SYSCALL32 should be used, for either 32- or 64-bit kernels. This
defaults to SYSENTER; use SYSCALL if the SYSCALL32 bit is also set.
As this removes ALL existing uses of X86_FEATURE_SYSENTER32, which is
a kernel-only synthetic feature bit, simply remove it and replace it
with X86_FEATURE_SYSFAST32.
This leaves an unused alternative for a true 32-bit kernel, but that
should really not matter in any way.
The clearing of X86_FEATURE_SYSCALL32 can be removed once the patches
for automatically clearing disabled features has been merged.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20251216212606.1325678-10-hpa@zytor.com
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/centaur.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 8 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/zhaoxin.c | 4 |
4 files changed, 10 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c index a3b55db35c96..9833f837141c 100644 --- a/arch/x86/kernel/cpu/centaur.c +++ b/arch/x86/kernel/cpu/centaur.c @@ -102,9 +102,6 @@ static void early_init_centaur(struct cpuinfo_x86 *c) (c->x86 >= 7)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#endif if (c->x86_power & (1 << 8)) { set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e7ab22fce3b5..1c3261cae40c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1068,6 +1068,9 @@ void get_cpu_cap(struct cpuinfo_x86 *c) init_scattered_cpuid_features(c); init_speculation_control(c); + if (IS_ENABLED(CONFIG_X86_64) || cpu_has(c, X86_FEATURE_SEP)) + set_cpu_cap(c, X86_FEATURE_SYSFAST32); + /* * Clear/Set all flags overridden by options, after probe. * This needs to happen each time we re-probe, which may happen @@ -1813,6 +1816,11 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) * that it can't be enabled in 32-bit mode. */ setup_clear_cpu_cap(X86_FEATURE_PCID); + + /* + * Never use SYSCALL on a 32-bit kernel + */ + setup_clear_cpu_cap(X86_FEATURE_SYSCALL32); #endif /* diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 98ae4c37c93e..646ff33c4651 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -236,9 +236,7 @@ static void early_init_intel(struct cpuinfo_x86 *c) clear_cpu_cap(c, X86_FEATURE_PSE); } -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#else +#ifndef CONFIG_X86_64 /* Netburst reports 64 bytes clflush size, but does IO in 128 bytes */ if (c->x86 == 15 && c->x86_cache_alignment == 64) c->x86_cache_alignment = 128; diff --git a/arch/x86/kernel/cpu/zhaoxin.c b/arch/x86/kernel/cpu/zhaoxin.c index 89b1c8a70fe8..031379b7d4fa 100644 --- a/arch/x86/kernel/cpu/zhaoxin.c +++ b/arch/x86/kernel/cpu/zhaoxin.c @@ -59,9 +59,7 @@ static void early_init_zhaoxin(struct cpuinfo_x86 *c) { if (c->x86 >= 0x6) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#endif + if (c->x86_power & (1 << 8)) { set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC); |