From: Mark Brown <broonie@kernel.org>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Brown <broonie@kernel.org>, Andrei Vagin <avagin@gmail.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/5] arm64: vdso: Add getcpu() implementation
Date: Fri, 5 Jun 2020 14:11:30 +0100 [thread overview]
Message-ID: <20200605131131.16491-5-broonie@kernel.org> (raw)
In-Reply-To: <20200605131131.16491-1-broonie@kernel.org>
Some applications, especially trace ones, benefit from avoiding the syscall
overhead on getcpu() calls so provide a vDSO implementation of it.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kernel/vdso/Makefile | 2 +-
arch/arm64/kernel/vdso/vdso.lds.S | 1 +
arch/arm64/kernel/vdso/vgetcpu.c | 48 +++++++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kernel/vdso/vgetcpu.c
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 279b1b9fb956..4ba2a159dd7c 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -11,7 +11,7 @@
ARCH_REL_TYPE_ABS := R_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
include $(srctree)/lib/vdso/Makefile
-obj-vdso := vgettimeofday.o note.o sigreturn.o
+obj-vdso := vgettimeofday.o note.o sigreturn.o vgetcpu.o
# Build rules
targets := $(obj-vdso) vdso.so vdso.so.dbg
diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
index 7ad2d3a0cd48..c2fd94f14b94 100644
--- a/arch/arm64/kernel/vdso/vdso.lds.S
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -77,6 +77,7 @@ VERSION
__kernel_gettimeofday;
__kernel_clock_gettime;
__kernel_clock_getres;
+ __kernel_getcpu;
local: *;
};
}
diff --git a/arch/arm64/kernel/vdso/vgetcpu.c b/arch/arm64/kernel/vdso/vgetcpu.c
new file mode 100644
index 000000000000..e8972e561e08
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vgetcpu.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM64 userspace implementations of getcpu()
+ *
+ * Copyright (C) 2020 ARM Limited
+ *
+ */
+
+#include <asm/unistd.h>
+#include <asm/vdso/datapage.h>
+
+struct getcpucache;
+
+static __always_inline
+int getcpu_fallback(unsigned int *_cpu, unsigned int *_node,
+ struct getcpucache *_c)
+{
+ register unsigned int *cpu asm("x0") = _cpu;
+ register unsigned int *node asm("x1") = _node;
+ register struct getcpucache *c asm("x2") = _c;
+ register long ret asm ("x0");
+ register long nr asm("x8") = __NR_getcpu;
+
+ asm volatile(
+ " svc #0\n"
+ : "=r" (ret)
+ : "r" (cpu), "r" (node), "r" (c), "r" (nr)
+ : "memory");
+
+ return ret;
+}
+
+int __kernel_getcpu(unsigned int *cpu, unsigned int *node,
+ struct getcpucache *c)
+{
+ struct vdso_cpu_data *cpu_data = __vdso_cpu_data();
+
+ if (cpu_data) {
+ if (cpu)
+ *cpu = cpu_data->cpu;
+ if (node)
+ *node = cpu_data->node;
+
+ return 0;
+ }
+
+ return getcpu_fallback(cpu, node, c);
+}
--
2.20.1
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next prev parent reply other threads:[~2020-06-05 13:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 13:11 [PATCH 0/5] arm64: vdso: getcpu() support Mark Brown
2020-06-05 13:11 ` [PATCH 1/5] arm64: vdso: Provide a define when building the vDSO Mark Brown
2020-06-05 13:11 ` [PATCH 2/5] arm64: vdso: Add per-CPU data Mark Brown
2020-06-05 13:11 ` [PATCH 3/5] arm64: vdso: Initialise the per-CPU vDSO data Mark Brown
2020-06-05 13:11 ` Mark Brown [this message]
2020-06-05 16:11 ` [PATCH 4/5] arm64: vdso: Add getcpu() implementation kernel test robot
2020-06-05 16:35 ` Mark Brown
2020-06-08 7:46 ` [kbuild-all] " Li Zhijian
2020-06-08 11:09 ` Mark Brown
2020-06-08 14:20 ` Philip Li
2020-06-07 2:04 ` kernel test robot
2020-06-05 13:11 ` [PATCH 5/5] selftests: vdso: Support arm64 in getcpu() test Mark Brown
2020-06-17 18:25 ` [PATCH 0/5] arm64: vdso: getcpu() support Mark Brown
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