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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-20 20:07:44 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-20 20:07:44 -0800
commit8831d718aa5a9540aaeb527a582af5fc140aed6e (patch)
tree0ad3bfa743e5201654da6dbb6f09d18c5a6797f5 /arch/x86/include
parentd00c4ed02e90c1a4290acdd4f9bc4d056a573859 (diff)
parent0a74d61c7d842b583f33f74d7a9e93201826f4c5 (diff)
downloadlinux-8831d718aa5a9540aaeb527a582af5fc140aed6e.tar.gz
Merge tag 'x86_fpu_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 FPU updates from Borislav Petkov: "x86 fpu usage optimization and cleanups: - make 64-bit kernel code which uses 387 insns request a x87 init (FNINIT) explicitly when using the FPU - misc cleanups" * tag 'x86_fpu_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu/xstate: Use sizeof() instead of a constant x86/fpu/64: Don't FNINIT in kernel_fpu_begin() x86/fpu: Make the EFI FPU calling convention explicit
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/efi.h24
-rw-r--r--arch/x86/include/asm/fpu/api.h12
2 files changed, 32 insertions, 4 deletions
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 627347af343a..4d0b126835b8 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -69,17 +69,33 @@ extern unsigned long efi_mixed_mode_stack_pa;
#f " called with too many arguments (" #p ">" #n ")"); \
})
+static inline void efi_fpu_begin(void)
+{
+ /*
+ * The UEFI calling convention (UEFI spec 2.3.2 and 2.3.4) requires
+ * that FCW and MXCSR (64-bit) must be initialized prior to calling
+ * UEFI code. (Oddly the spec does not require that the FPU stack
+ * be empty.)
+ */
+ kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
+}
+
+static inline void efi_fpu_end(void)
+{
+ kernel_fpu_end();
+}
+
#ifdef CONFIG_X86_32
#define arch_efi_call_virt_setup() \
({ \
- kernel_fpu_begin(); \
+ efi_fpu_begin(); \
firmware_restrict_branch_speculation_start(); \
})
#define arch_efi_call_virt_teardown() \
({ \
firmware_restrict_branch_speculation_end(); \
- kernel_fpu_end(); \
+ efi_fpu_end(); \
})
#define arch_efi_call_virt(p, f, args...) p->f(args)
@@ -98,7 +114,7 @@ extern asmlinkage u64 __efi_call(void *fp, ...);
#define arch_efi_call_virt_setup() \
({ \
efi_sync_low_kernel_mappings(); \
- kernel_fpu_begin(); \
+ efi_fpu_begin(); \
firmware_restrict_branch_speculation_start(); \
efi_enter_mm(); \
})
@@ -110,7 +126,7 @@ extern asmlinkage u64 __efi_call(void *fp, ...);
({ \
efi_leave_mm(); \
firmware_restrict_branch_speculation_end(); \
- kernel_fpu_end(); \
+ efi_fpu_end(); \
})
#ifdef CONFIG_KASAN
diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index 67a4f1cb2aac..ed33a14188f6 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -32,7 +32,19 @@ extern void fpregs_mark_activate(void);
/* Code that is unaware of kernel_fpu_begin_mask() can use this */
static inline void kernel_fpu_begin(void)
{
+#ifdef CONFIG_X86_64
+ /*
+ * Any 64-bit code that uses 387 instructions must explicitly request
+ * KFPU_387.
+ */
+ kernel_fpu_begin_mask(KFPU_MXCSR);
+#else
+ /*
+ * 32-bit kernel code may use 387 operations as well as SSE2, etc,
+ * as long as it checks that the CPU has the required capability.
+ */
kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
+#endif
}
/*