From: Breno Leitao Date: Sat, 23 May 2026 16:59:26 +0000 (-0400) Subject: arm64: arch_timer: reuse arch_timer_read_cnt{p,v}ct_el0() helpers X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=11c33ffb3a4e65e775e9bd814eb71df06ea7c847;p=thirdparty%2Fkernel%2Flinux.git arm64: arch_timer: reuse arch_timer_read_cnt{p,v}ct_el0() helpers __arch_counter_get_cntpct() and __arch_counter_get_cntvct() open-code the same ECV-aware ALTERNATIVE block that arch_timer_read_cntpct_el0() and arch_timer_read_cntvct_el0() already provide in the same header. The two pairs are byte-for-byte identical except for the trailing arch_counter_enforce_ordering() the __arch_counter_get_* variants add. Replace the duplicated inline assembly in __arch_counter_get_cntpct() and __arch_counter_get_cntvct() with calls to the corresponding helpers. This mirrors commit 00b39d150986 ("arm64: vdso: Use __arch_counter_get_cntvct()"), which removed similar duplication from the vDSO, and keeps the system-counter read sequence in a single place, reducing assembly code in the kernell No functional change: the resulting inline assembly, alternatives, and clobbers are unchanged; only the source-level expression of the read moves into the existing helper. Verified by rebuilding the consumers of these helpers before and after the change and comparing the resulting disassembly: - arch/arm64/kernel/vdso/vdso.so (final linked vDSO): bit-identical (same sha256 across rebuilds) - arch/arm64/kernel/vdso/vgettimeofday.o: identical disassembly - arch/arm64/lib/delay.o: identical disassembly - drivers/clocksource/arm_arch_timer.o: same 50 functions with byte-identical instruction streams; only difference is function ordering inside .text and NOP padding, with no opcodes added or removed. Signed-off-by: Breno Leitao Signed-off-by: Will Deacon --- diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index f5794d50f51dc..6717209df05ba 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -178,12 +178,8 @@ static __always_inline u64 __arch_counter_get_cntpct_stable(void) static __always_inline u64 __arch_counter_get_cntpct(void) { - u64 cnt; + u64 cnt = arch_timer_read_cntpct_el0(); - asm volatile(ALTERNATIVE("isb\n mrs %0, cntpct_el0", - "nop\n" __mrs_s("%0", SYS_CNTPCTSS_EL0), - ARM64_HAS_ECV) - : "=r" (cnt)); arch_counter_enforce_ordering(cnt); return cnt; } @@ -199,12 +195,8 @@ static __always_inline u64 __arch_counter_get_cntvct_stable(void) static __always_inline u64 __arch_counter_get_cntvct(void) { - u64 cnt; + u64 cnt = arch_timer_read_cntvct_el0(); - asm volatile(ALTERNATIVE("isb\n mrs %0, cntvct_el0", - "nop\n" __mrs_s("%0", SYS_CNTVCTSS_EL0), - ARM64_HAS_ECV) - : "=r" (cnt)); arch_counter_enforce_ordering(cnt); return cnt; }