diff options
author | Stefan Agner <stefan.agner@toradex.com> | 2019-06-03 10:59:09 +0200 |
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committer | Stefan Agner <stefan.agner@toradex.com> | 2019-06-03 10:59:09 +0200 |
commit | 2115c1bc6e396d5ffe9ecbe394d1c50a6e25c404 (patch) | |
tree | 20fff445991414f23c0a29237940b75cd756de86 /arch/arm64/include/asm/arch_timer.h | |
parent | b794ea49ba3816c0d5cf05506964a8e69ce4efa3 (diff) | |
parent | 3f7c1cab1a61108821cf47dda8a32ed25cc3588b (diff) |
Merge tag 'v5.0.19' into toradex_5.0.ytoradex_5.0.y
This is the 5.0.19 stable release
Diffstat (limited to 'arch/arm64/include/asm/arch_timer.h')
-rw-r--r-- | arch/arm64/include/asm/arch_timer.h | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index f2a234d6516c..93e07512b4b6 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -148,18 +148,47 @@ static inline void arch_timer_set_cntkctl(u32 cntkctl) isb(); } +/* + * Ensure that reads of the counter are treated the same as memory reads + * for the purposes of ordering by subsequent memory barriers. + * + * This insanity brought to you by speculative system register reads, + * out-of-order memory accesses, sequence locks and Thomas Gleixner. + * + * http://lists.infradead.org/pipermail/linux-arm-kernel/2019-February/631195.html + */ +#define arch_counter_enforce_ordering(val) do { \ + u64 tmp, _val = (val); \ + \ + asm volatile( \ + " eor %0, %1, %1\n" \ + " add %0, sp, %0\n" \ + " ldr xzr, [%0]" \ + : "=r" (tmp) : "r" (_val)); \ +} while (0) + static inline u64 arch_counter_get_cntpct(void) { + u64 cnt; + isb(); - return arch_timer_reg_read_stable(cntpct_el0); + cnt = arch_timer_reg_read_stable(cntpct_el0); + arch_counter_enforce_ordering(cnt); + return cnt; } static inline u64 arch_counter_get_cntvct(void) { + u64 cnt; + isb(); - return arch_timer_reg_read_stable(cntvct_el0); + cnt = arch_timer_reg_read_stable(cntvct_el0); + arch_counter_enforce_ordering(cnt); + return cnt; } +#undef arch_counter_enforce_ordering + static inline int arch_timer_arch_init(void) { return 0; |