From d6d6d50f1e801a790a242c80eeda261e36c43b7b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Mar 2022 20:43:21 +0200 Subject: [PATCH] x86/fpu/xstate: Consolidate size calculations Use the offset calculation to do the size calculation which avoids yet another series of CPUID instructions for each invocation. [ Fix the FP/SSE only case which missed to take the xstate header into account, as Reported-by: kernel test robot ] Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx --- arch/x86/kernel/fpu/xstate.c | 49 ++++++++------------------------------------ 1 file changed, 8 insertions(+), 41 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 5ac934b..39e1c86 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -385,25 +385,6 @@ static void __init setup_init_fpu_buf(void) fxsave(&init_fpstate.regs.fxsave); } -static int xfeature_uncompacted_offset(int xfeature_nr) -{ - u32 eax, ebx, ecx, edx; - - /* - * Only XSAVES supports supervisor states and it uses compacted - * format. Checking a supervisor state's uncompacted offset is - * an error. - */ - if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) { - WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); - return -1; - } - - CHECK_XFEATURE(xfeature_nr); - cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); - return ebx; -} - int xfeature_size(int xfeature_nr) { u32 eax, ebx, ecx, edx; @@ -581,29 +562,15 @@ static bool __init check_xstate_against_struct(int nr) static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted) { - unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE; - int i; + unsigned int topmost = fls64(xfeatures) - 1; + unsigned int offset = xstate_offsets[topmost]; - for_each_extended_xfeature(i, xfeatures) { - /* Align from the end of the previous feature */ - if (xfeature_is_aligned64(i)) - size = ALIGN(size, 64); - /* - * 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 (!compacted) - size = xfeature_uncompacted_offset(i); - /* - * Add the feature size even for non-compacted format - * to make the end result correct - */ - size += xfeature_size(i); - } - return size; + if (topmost <= XFEATURE_SSE) + return sizeof(struct xregs_state); + + if (compacted) + offset = xfeature_get_offset(xfeatures, topmost); + return offset + xstate_sizes[topmost]; } /* -- 2.7.4