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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9752082560
Mark vget_cycles() as __always_inline, so gcc is never tempted to make the vsyscall vread_tsc() dive into kernel text, with resulting SIGSEGV. This was a self-inflicted wound: I've not seen that happen with unhacked sources; but for debug reasons I'd changed my x86/Makefile to compile no-unit-at-a-time, and that in conjunction with OPTIMIZE_INLINING=y ended up with vget_cycles() in kernel text. Perhaps it can happen in other ways: safer to use __always_inline. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
65 lines
1.2 KiB
C
65 lines
1.2 KiB
C
/*
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* x86 TSC related functions
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*/
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#ifndef _ASM_X86_TSC_H
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#define _ASM_X86_TSC_H
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#include <asm/processor.h>
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#define NS_SCALE 10 /* 2^10, carefully chosen */
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#define US_SCALE 32 /* 2^32, arbitralrily chosen */
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/*
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* Standard way to access the cycle counter.
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*/
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typedef unsigned long long cycles_t;
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extern unsigned int cpu_khz;
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extern unsigned int tsc_khz;
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extern void disable_TSC(void);
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static inline cycles_t get_cycles(void)
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{
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unsigned long long ret = 0;
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#ifndef CONFIG_X86_TSC
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if (!cpu_has_tsc)
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return 0;
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#endif
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rdtscll(ret);
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return ret;
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}
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static __always_inline cycles_t vget_cycles(void)
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{
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/*
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* We only do VDSOs on TSC capable CPUs, so this shouldnt
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* access boot_cpu_data (which is not VDSO-safe):
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*/
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#ifndef CONFIG_X86_TSC
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if (!cpu_has_tsc)
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return 0;
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#endif
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return (cycles_t)__native_read_tsc();
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}
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extern void tsc_init(void);
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extern void mark_tsc_unstable(char *reason);
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extern int unsynchronized_tsc(void);
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extern void init_tsc_clocksource(void);
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int check_tsc_unstable(void);
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/*
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* Boot-time check whether the TSCs are synchronized across
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* all CPUs/cores:
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*/
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extern void check_tsc_sync_source(int cpu);
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extern void check_tsc_sync_target(void);
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extern void tsc_calibrate(void);
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extern int notsc_setup(char *);
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#endif
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