![H. Peter Anvin](/assets/img/avatar_default.png)
Impact: bogus error codes (+other?) on x86-64 The rdmsr_safe/wrmsr_safe routines have macros for the handling of the edx:eax arguments. Those macros take a variable number of assembly arguments. This is rather inherently incompatible with using %digit-style escapes in the inline assembly; replace those with %[name]-style escapes. This fixes miscompilation on x86-64, which at the very least caused bogus return values. It is possible that this could also corrupt the return value; I am not sure. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
225 lines
5.8 KiB
C
225 lines
5.8 KiB
C
#ifndef __ASM_X86_MSR_H_
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#define __ASM_X86_MSR_H_
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#include <asm/msr-index.h>
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#ifndef __ASSEMBLY__
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# include <linux/types.h>
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#endif
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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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#include <asm/asm.h>
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#include <asm/errno.h>
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static inline unsigned long long native_read_tscp(unsigned int *aux)
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{
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unsigned long low, high;
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asm volatile(".byte 0x0f,0x01,0xf9"
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: "=a" (low), "=d" (high), "=c" (*aux));
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return low | ((u64)high << 32);
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}
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/*
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* i386 calling convention returns 64-bit value in edx:eax, while
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* x86_64 returns at rax. Also, the "A" constraint does not really
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* mean rdx:rax in x86_64, so we need specialized behaviour for each
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* architecture
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*/
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#ifdef CONFIG_X86_64
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#define DECLARE_ARGS(val, low, high) unsigned low, high
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#define EAX_EDX_VAL(val, low, high) ((low) | ((u64)(high) << 32))
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#define EAX_EDX_ARGS(val, low, high) "a" (low), "d" (high)
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#define EAX_EDX_RET(val, low, high) "=a" (low), "=d" (high)
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#else
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#define DECLARE_ARGS(val, low, high) unsigned long long val
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#define EAX_EDX_VAL(val, low, high) (val)
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#define EAX_EDX_ARGS(val, low, high) "A" (val)
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#define EAX_EDX_RET(val, low, high) "=A" (val)
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#endif
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static inline unsigned long long native_read_msr(unsigned int msr)
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{
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DECLARE_ARGS(val, low, high);
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asm volatile("rdmsr" : EAX_EDX_RET(val, low, high) : "c" (msr));
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return EAX_EDX_VAL(val, low, high);
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}
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static inline unsigned long long native_read_msr_safe(unsigned int msr,
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int *err)
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{
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DECLARE_ARGS(val, low, high);
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asm volatile("2: rdmsr ; xor %[err],%[err]\n"
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"1:\n\t"
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".section .fixup,\"ax\"\n\t"
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"3: mov %[fault],%[err] ; jmp 1b\n\t"
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".previous\n\t"
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_ASM_EXTABLE(2b, 3b)
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: [err] "=r" (*err), EAX_EDX_RET(val, low, high)
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: "c" (msr), [fault] "i" (-EFAULT));
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return EAX_EDX_VAL(val, low, high);
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}
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static inline void native_write_msr(unsigned int msr,
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unsigned low, unsigned high)
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{
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asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory");
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}
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static inline int native_write_msr_safe(unsigned int msr,
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unsigned low, unsigned high)
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{
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int err;
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asm volatile("2: wrmsr ; xor %[err],%[err]\n"
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"1:\n\t"
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".section .fixup,\"ax\"\n\t"
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"3: mov %[fault],%[err] ; jmp 1b\n\t"
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".previous\n\t"
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_ASM_EXTABLE(2b, 3b)
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: [err] "=a" (err)
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: "c" (msr), "0" (low), "d" (high),
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[fault] "i" (-EFAULT)
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: "memory");
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return err;
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}
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extern unsigned long long native_read_tsc(void);
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static __always_inline unsigned long long __native_read_tsc(void)
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{
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DECLARE_ARGS(val, low, high);
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rdtsc_barrier();
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asm volatile("rdtsc" : EAX_EDX_RET(val, low, high));
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rdtsc_barrier();
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return EAX_EDX_VAL(val, low, high);
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}
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static inline unsigned long long native_read_pmc(int counter)
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{
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DECLARE_ARGS(val, low, high);
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asm volatile("rdpmc" : EAX_EDX_RET(val, low, high) : "c" (counter));
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return EAX_EDX_VAL(val, low, high);
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}
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#ifdef CONFIG_PARAVIRT
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#include <asm/paravirt.h>
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#else
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#include <linux/errno.h>
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/*
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* Access to machine-specific registers (available on 586 and better only)
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* Note: the rd* operations modify the parameters directly (without using
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* pointer indirection), this allows gcc to optimize better
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*/
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#define rdmsr(msr, val1, val2) \
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do { \
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u64 __val = native_read_msr((msr)); \
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(val1) = (u32)__val; \
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(val2) = (u32)(__val >> 32); \
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} while (0)
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static inline void wrmsr(unsigned msr, unsigned low, unsigned high)
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{
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native_write_msr(msr, low, high);
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}
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#define rdmsrl(msr, val) \
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((val) = native_read_msr((msr)))
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#define wrmsrl(msr, val) \
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native_write_msr((msr), (u32)((u64)(val)), (u32)((u64)(val) >> 32))
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/* wrmsr with exception handling */
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static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)
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{
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return native_write_msr_safe(msr, low, high);
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}
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/* rdmsr with exception handling */
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#define rdmsr_safe(msr, p1, p2) \
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({ \
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int __err; \
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u64 __val = native_read_msr_safe((msr), &__err); \
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(*p1) = (u32)__val; \
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(*p2) = (u32)(__val >> 32); \
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__err; \
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})
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static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
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{
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int err;
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*p = native_read_msr_safe(msr, &err);
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return err;
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}
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#define rdtscl(low) \
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((low) = (u32)native_read_tsc())
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#define rdtscll(val) \
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((val) = native_read_tsc())
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#define rdpmc(counter, low, high) \
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do { \
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u64 _l = native_read_pmc((counter)); \
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(low) = (u32)_l; \
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(high) = (u32)(_l >> 32); \
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} while (0)
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#define rdtscp(low, high, aux) \
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do { \
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unsigned long long _val = native_read_tscp(&(aux)); \
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(low) = (u32)_val; \
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(high) = (u32)(_val >> 32); \
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} while (0)
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#define rdtscpll(val, aux) (val) = native_read_tscp(&(aux))
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#endif /* !CONFIG_PARAVIRT */
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#define checking_wrmsrl(msr, val) wrmsr_safe((msr), (u32)(val), \
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(u32)((val) >> 32))
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#define write_tsc(val1, val2) wrmsr(0x10, (val1), (val2))
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#define write_rdtscp_aux(val) wrmsr(0xc0000103, (val), 0)
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#ifdef CONFIG_SMP
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int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
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int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
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int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
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int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
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#else /* CONFIG_SMP */
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static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
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{
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rdmsr(msr_no, *l, *h);
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return 0;
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}
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static inline int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
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{
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wrmsr(msr_no, l, h);
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return 0;
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}
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static inline int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no,
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u32 *l, u32 *h)
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{
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return rdmsr_safe(msr_no, l, h);
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}
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static inline int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
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{
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return wrmsr_safe(msr_no, l, h);
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}
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#endif /* CONFIG_SMP */
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#endif /* __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif
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