The following commit has been merged into the x86/fpu branch of tip: Commit-ID: c33f0a81a2cf3920465309ce683534751bb86485 Gitweb: https://git.kernel.org/tip/c33f0a81a2cf3920465309ce683534751bb86485 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 21 Oct 2021 15:55:09 -07:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Tue, 26 Oct 2021 10:18:09 +02:00 x86/fpu: Add fpu_state_config::legacy_features The upcoming prctl() which is required to request the permission for a dynamically enabled feature will also provide an option to retrieve the supported features. If the CPU does not support XSAVE, the supported features would be 0 even when the CPU supports FP and SSE. Provide separate storage for the legacy feature set to avoid that and fill in the bits in the legacy init function. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/20211021225527.10184-6-chang.seok.bae@xxxxxxxxx --- arch/x86/include/asm/fpu/types.h | 7 +++++++ arch/x86/kernel/fpu/init.c | 9 ++++++--- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index c3ec562..595122f 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -503,6 +503,13 @@ struct fpu_state_config { * be requested by user space before usage. */ u64 default_features; + /* + * @legacy_features: + * + * Features which can be reported back to user space + * even without XSAVE support, i.e. legacy features FP + SSE + */ + u64 legacy_features; }; /* FPU state configuration information */ diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 7074154..621f4b6 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -193,12 +193,15 @@ static void __init fpu__init_system_xstate_size_legacy(void) * Note that the size configuration might be overwritten later * during fpu__init_system_xstate(). */ - if (!cpu_feature_enabled(X86_FEATURE_FPU)) + if (!cpu_feature_enabled(X86_FEATURE_FPU)) { size = sizeof(struct swregs_state); - else if (cpu_feature_enabled(X86_FEATURE_FXSR)) + } else if (cpu_feature_enabled(X86_FEATURE_FXSR)) { size = sizeof(struct fxregs_state); - else + fpu_user_cfg.legacy_features = XFEATURE_MASK_FPSSE; + } else { size = sizeof(struct fregs_state); + fpu_user_cfg.legacy_features = XFEATURE_MASK_FP; + } fpu_kernel_cfg.max_size = size; fpu_kernel_cfg.default_size = size;
![]() |