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| author | Sohil Mehta <sohil.mehta@intel.com> | 2026-03-09 21:10:29 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2026-03-20 01:11:13 +0300 |
| commit | 584d752b8a1f0ee3a7d5a831e55623c10e7ca0ee (patch) | |
| tree | 479199285d116e080d5af9ce8a8686fca0cc9af4 | |
| parent | b36d1f53d90c869d5f02fe0d8603f825013e746e (diff) | |
| download | linux-584d752b8a1f0ee3a7d5a831e55623c10e7ca0ee.tar.xz | |
x86/cpu: Remove LASS restriction on vsyscall emulation
Vsyscall emulation has two modes of operation: XONLY and EMULATE. The
default XONLY mode is now supported with a LASS-triggered #GP. OTOH,
LASS is disabled if someone requests the deprecated EMULATE mode via the
vsyscall=emulate command line option. So, remove the restriction on LASS
when the overall vsyscall emulation support is compiled in.
As a result, there is no need for setup_lass() anymore. LASS is enabled
by default through a late_initcall().
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Reviewed-by:
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260309181029.398498-6-sohil.mehta@intel.com
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 15 |
1 files changed, 0 insertions, 15 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 3557f0e6b3aa..02472fc763d9 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -406,20 +406,6 @@ out: cr4_clear_bits(X86_CR4_UMIP); } -static __always_inline void setup_lass(struct cpuinfo_x86 *c) -{ - if (!cpu_feature_enabled(X86_FEATURE_LASS)) - return; - - /* - * Legacy vsyscall page access causes a #GP when LASS is active. - * Disable LASS because the #GP handler doesn't support vsyscall - * emulation. - */ - if (IS_ENABLED(CONFIG_X86_VSYSCALL_EMULATION)) - setup_clear_cpu_cap(X86_FEATURE_LASS); -} - static int enable_lass(unsigned int cpu) { cr4_set_bits(X86_CR4_LASS); @@ -2061,7 +2047,6 @@ static void identify_cpu(struct cpuinfo_x86 *c) setup_smep(c); setup_smap(c); setup_umip(c); - setup_lass(c); /* Enable FSGSBASE instructions if available. */ if (cpu_has(c, X86_FEATURE_FSGSBASE)) { |