The following commit has been merged into the x86/fpu branch of tip: Commit-ID: cd9ae761744912a96d7fd968b9c0173594e3f6be Gitweb: https://git.kernel.org/tip/cd9ae761744912a96d7fd968b9c0173594e3f6be Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Fri, 15 Oct 2021 01:09:32 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Thu, 21 Oct 2021 19:37:53 +02:00 x86/fpu/xstate: Cleanup size calculations The size calculations are partially unreadable gunk. Clean them up. No functional change. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/20211014230739.241223689@xxxxxxxxxxxxx --- arch/x86/kernel/fpu/xstate.c | 82 +++++++++++++++++++---------------- 1 file changed, 46 insertions(+), 36 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 4cfd3bc..c5582bd 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -527,7 +527,7 @@ static void __init __xstate_dump_leaves(void) * that our software representation matches what the CPU * tells us about the state's size. */ -static void __init check_xstate_against_struct(int nr) +static bool __init check_xstate_against_struct(int nr) { /* * Ask the CPU for the size of the state. @@ -557,7 +557,9 @@ static void __init check_xstate_against_struct(int nr) ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) { WARN_ONCE(1, "no structure for xstate: %d\n", nr); XSTATE_WARN_ON(1); + return false; } + return true; } /* @@ -569,38 +571,44 @@ static void __init check_xstate_against_struct(int nr) * covered by these checks. Only the size of the buffer for task->fpu * is checked here. */ -static void __init do_extra_xstate_size_checks(void) +static bool __init paranoid_xstate_size_valid(unsigned int kernel_size) { - int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; + bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES); + unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE; int i; for_each_extended_xfeature(i, xfeatures_mask_all) { - check_xstate_against_struct(i); + if (!check_xstate_against_struct(i)) + return false; /* * Supervisor state components can be managed only by * XSAVES. */ - if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) - XSTATE_WARN_ON(xfeature_is_supervisor(i)); + if (!compacted && xfeature_is_supervisor(i)) { + XSTATE_WARN_ON(1); + return false; + } /* Align from the end of the previous feature */ if (xfeature_is_aligned(i)) - paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64); + size = ALIGN(size, 64); /* - * The offset of a given state in the non-compacted - * format is given to us in a CPUID leaf. We check - * them for being ordered (increasing offsets) in - * setup_xstate_features(). XSAVES uses compacted format. + * In compacted format the enabled features are packed, + * i.e. disabled features do not occupy space. + * + * In non-compacted format the offsets are fixed and + * disabled states still occupy space in the memory buffer. */ - if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) - paranoid_xstate_size = xfeature_uncompacted_offset(i); + if (!compacted) + size = xfeature_uncompacted_offset(i); /* - * The compacted-format offset always depends on where - * the previous state ended. + * Add the feature size even for non-compacted format + * to make the end result correct */ - paranoid_xstate_size += xfeature_size(i); + size += xfeature_size(i); } - XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size); + XSTATE_WARN_ON(size != kernel_size); + return size == kernel_size; } /* @@ -653,7 +661,7 @@ static unsigned int __init get_xsaves_size_no_independent(void) return size; } -static unsigned int __init get_xsave_size(void) +static unsigned int __init get_xsave_size_user(void) { unsigned int eax, ebx, ecx, edx; /* @@ -684,31 +692,33 @@ static bool __init is_supported_xstate_size(unsigned int test_xstate_size) static int __init init_xstate_size(void) { /* Recompute the context size for enabled features: */ - unsigned int possible_xstate_size; - unsigned int xsave_size; + unsigned int user_size, kernel_size; - xsave_size = get_xsave_size(); + /* Uncompacted user space size */ + user_size = get_xsave_size_user(); - if (boot_cpu_has(X86_FEATURE_XSAVES)) - possible_xstate_size = get_xsaves_size_no_independent(); + /* + * XSAVES kernel size includes supervisor states and + * uses compacted format. + * + * XSAVE does not support supervisor states so + * kernel and user size is identical. + */ + if (cpu_feature_enabled(X86_FEATURE_XSAVES)) + kernel_size = get_xsaves_size_no_independent(); else - possible_xstate_size = xsave_size; + kernel_size = user_size; - /* Ensure we have the space to store all enabled: */ - if (!is_supported_xstate_size(possible_xstate_size)) + /* Ensure we have the space to store all enabled features. */ + if (!is_supported_xstate_size(kernel_size)) return -EINVAL; - /* - * The size is OK, we are definitely going to use xsave, - * make it known to the world that we need more space. - */ - fpu_kernel_xstate_size = possible_xstate_size; - do_extra_xstate_size_checks(); + if (!paranoid_xstate_size_valid(kernel_size)) + return -EINVAL; + + fpu_kernel_xstate_size = kernel_size; + fpu_user_xstate_size = user_size; - /* - * User space is always in standard format. - */ - fpu_user_xstate_size = xsave_size; return 0; }
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