Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH] x86/xsave: Robustify and merge macros | Date | Thu, 2 Apr 2015 15:11:22 +0200 |
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From: Borislav Petkov <bp@suse.de>
Previously, we did call an XSAVE/XRSTOR variant through alternatives and did potential exception handling resulting from the instruction execution in a second inline asm. Which was misleading and error prone, see
06c8173eb92b ("x86/fpu/xsaves: Fix improper uses of __ex_table")
for an example.
Add single macros which combine the alternatives and the exception handling.
While at it, remove the SYSTEM_BOOTING checks in favor of static_cpu_has_safe() which works regardless of system state.
Cleanup comments.
Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> --- arch/x86/include/asm/xsave.h | 141 ++++++++++++++++++++++--------------------- 1 file changed, 73 insertions(+), 68 deletions(-)
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h index c9a6d68b8d62..e6c7986c95df 100644 --- a/arch/x86/include/asm/xsave.h +++ b/arch/x86/include/asm/xsave.h @@ -67,6 +67,66 @@ extern int init_fpu(struct task_struct *child); _ASM_EXTABLE(1b, 3b) \ : [err] "=r" (err) +#define XSTATE_OP(op, st, lmask, hmask, err) \ + asm volatile("1:" op "\n\t" \ + "2:\n\t" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n\t" \ + "3: movl $-1,%[err]\n\t" \ + "jmp 2b\n\t" \ + ".popsection\n\t" \ + _ASM_EXTABLE(1b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ + : "memory") + +/* + * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact + * format and supervisor states in addition to modified optimization in + * XSAVEOPT. + * + * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT + * supports modified optimization which is not supported by XSAVE. + * + * We use XSAVE as a fallback. + * + * 661 and alt_end_marker labels below are defined in ALTERNATIVE* and we're + * reusing them here so as not to clutter this macro unnecessarily. + */ +#define XSTATE_XSAVE(st, lmask, hmask, err) \ + asm volatile(ALTERNATIVE_2(XSAVE, \ + XSAVEOPT, X86_FEATURE_XSAVEOPT, \ + XSAVES, X86_FEATURE_XSAVES) \ + "\n" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n" \ + "3: movl $-1, %[err]\n" \ + "jmp " alt_end_marker "b\n" \ + ".popsection\n" \ + _ASM_EXTABLE(661b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "a" (lmask), "d" (hmask) \ + : "memory") + +/* + * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact + * XSAVE area format. + */ +#define XSTATE_XRESTORE(st, lmask, hmask, err) \ + asm volatile(ALTERNATIVE(XRSTOR, \ + XRSTORS, X86_FEATURE_XSAVES) \ + "\n" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n" \ + "3: movl $-1, %[err]\n" \ + "jmp 663b\n" \ + ".popsection\n" \ + _ASM_EXTABLE(661b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ + : "memory") + + /* * This function is called only during boot time when x86 caps are not set * up and alternative can not be used yet. @@ -75,22 +135,13 @@ static inline int xsave_state_booting(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; - - WARN_ON(system_state != SYSTEM_BOOTING); + int err; - if (boot_cpu_has(X86_FEATURE_XSAVES)) - asm volatile("1:"XSAVES"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + if (static_cpu_has_safe(X86_FEATURE_XSAVES)) + XSTATE_OP(XSAVES, fx, lmask, hmask, err); else - asm volatile("1:"XSAVE"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + XSTATE_OP(XSAVE, fx, lmask, hmask, err); + return err; } @@ -102,22 +153,12 @@ static inline int xrstor_state_booting(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; - - WARN_ON(system_state != SYSTEM_BOOTING); + int err; - if (boot_cpu_has(X86_FEATURE_XSAVES)) - asm volatile("1:"XRSTORS"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + if (static_cpu_has_safe(X86_FEATURE_XSAVES)) + XSTATE_OP(XRSTORS, fx, lmask, hmask, err); else - asm volatile("1:"XRSTOR"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + XSTATE_OP(XRSTOR, fx, lmask, hmask, err); return err; } @@ -128,31 +169,9 @@ static inline int xsave_state(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; + int err; - /* - * If xsaves is enabled, xsaves replaces xsaveopt because - * it supports compact format and supervisor states in addition to - * modified optimization in xsaveopt. - * - * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave - * because xsaveopt supports modified optimization which is not - * supported by xsave. - * - * If none of xsaves and xsaveopt is enabled, use xsave. - */ - alternative_input_2( - "1:"XSAVE, - XSAVEOPT, - X86_FEATURE_XSAVEOPT, - XSAVES, - X86_FEATURE_XSAVES, - [fx] "D" (fx), "a" (lmask), "d" (hmask) : - "memory"); - asm volatile("2:\n\t" - xstate_fault - : "0" (0) - : "memory"); + XSTATE_XSAVE(fx, lmask, hmask, err); return err; } @@ -162,25 +181,11 @@ static inline int xsave_state(struct xsave_struct *fx, u64 mask) */ static inline int xrstor_state(struct xsave_struct *fx, u64 mask) { - int err = 0; + int err; u32 lmask = mask; u32 hmask = mask >> 32; - /* - * Use xrstors to restore context if it is enabled. xrstors supports - * compacted format of xsave area which is not supported by xrstor. - */ - alternative_input( - "1: " XRSTOR, - XRSTORS, - X86_FEATURE_XSAVES, - "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); - - asm volatile("2:\n" - xstate_fault - : "0" (0) - : "memory"); + XSTATE_XRESTORE(fx, lmask, hmask, err); return err; } -- 2.3.3
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