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authorDapeng Mi <dapeng1.mi@linux.intel.com>2026-09-17 09:52:33 +0800
committerIngo Molnar <mingo@kernel.org>2026-09-22 11:37:46 +0200
commit0102c8c7fdfc4bd700971daff2b94470f4eafae4 (patch)
tree531306c2299f9a269f0a986e29f17ba972180104 /arch/arm/common/vlock.S
downloadlinux-stable-0102c8c7fdfc4bd700971daff2b94470f4eafae4.tar.gz
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perf/x86/intel: Rename DMR offcore_rsp attribute to offmodule_rspgrafted
DMR introduces Offmodule Response events in place of the legacy Offcore Response events, but it still exposes the inherited offcore_rsp PMU attribute for programming the corresponding MSR data. Rename the DMR PMU attribute to offmodule_rsp so the sysfs interface matches the underlying event name and avoids user & tooling confusion. Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://patch.msgid.link/20260917015234.981153-12-dapeng1.mi@linux.intel.com
Diffstat (limited to 'arch/arm/common/vlock.S')
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1 files changed, 101 insertions, 0 deletions
diff --git a/arch/arm/common/vlock.S b/arch/arm/common/vlock.S
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+++ b/arch/arm/common/vlock.S
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+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * vlock.S - simple voting lock implementation for ARM
+ *
+ * Created by: Dave Martin, 2012-08-16
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * This algorithm is described in more detail in
+ * Documentation/arch/arm/vlocks.rst.
+ */
+
+#include <linux/linkage.h>
+#include "vlock.h"
+
+.arch armv7-a
+
+/* Select different code if voting flags can fit in a single word. */
+#if VLOCK_VOTING_SIZE > 4
+#define FEW(x...)
+#define MANY(x...) x
+#else
+#define FEW(x...) x
+#define MANY(x...)
+#endif
+
+@ voting lock for first-man coordination
+
+.macro voting_begin rbase:req, rcpu:req, rscratch:req
+ mov \rscratch, #1
+ strb \rscratch, [\rbase, \rcpu]
+ dmb
+.endm
+
+.macro voting_end rbase:req, rcpu:req, rscratch:req
+ dmb
+ mov \rscratch, #0
+ strb \rscratch, [\rbase, \rcpu]
+ dsb st
+ sev
+.endm
+
+/*
+ * The vlock structure must reside in Strongly-Ordered or Device memory.
+ * This implementation deliberately eliminates most of the barriers which
+ * would be required for other memory types, and assumes that independent
+ * writes to neighbouring locations within a cacheline do not interfere
+ * with one another.
+ */
+
+@ r0: lock structure base
+@ r1: CPU ID (0-based index within cluster)
+ENTRY(vlock_trylock)
+ add r1, r1, #VLOCK_VOTING_OFFSET
+
+ voting_begin r0, r1, r2
+
+ ldrb r2, [r0, #VLOCK_OWNER_OFFSET] @ check whether lock is held
+ cmp r2, #VLOCK_OWNER_NONE
+ bne trylock_fail @ fail if so
+
+ @ Control dependency implies strb not observable before previous ldrb.
+
+ strb r1, [r0, #VLOCK_OWNER_OFFSET] @ submit my vote
+
+ voting_end r0, r1, r2 @ implies DMB
+
+ @ Wait for the current round of voting to finish:
+
+ MANY( mov r3, #VLOCK_VOTING_OFFSET )
+0:
+ MANY( ldr r2, [r0, r3] )
+ FEW( ldr r2, [r0, #VLOCK_VOTING_OFFSET] )
+ cmp r2, #0
+ wfene
+ bne 0b
+ MANY( add r3, r3, #4 )
+ MANY( cmp r3, #VLOCK_VOTING_OFFSET + VLOCK_VOTING_SIZE )
+ MANY( bne 0b )
+
+ @ Check who won:
+
+ dmb
+ ldrb r2, [r0, #VLOCK_OWNER_OFFSET]
+ eor r0, r1, r2 @ zero if I won, else nonzero
+ bx lr
+
+trylock_fail:
+ voting_end r0, r1, r2
+ mov r0, #1 @ nonzero indicates that I lost
+ bx lr
+ENDPROC(vlock_trylock)
+
+@ r0: lock structure base
+ENTRY(vlock_unlock)
+ dmb
+ mov r1, #VLOCK_OWNER_NONE
+ strb r1, [r0, #VLOCK_OWNER_OFFSET]
+ dsb st
+ sev
+ bx lr
+ENDPROC(vlock_unlock)