linux-kernel - [PATCH v3 5/7] um: vdso: Remove getcpu support on x86

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Message-Id: <20250914155658.1028790-6-tiwei.bie@linux.dev>
Date: Sun, 14 Sep 2025 23:56:56 +0800
From: Tiwei Bie <tiwei.bie@...ux.dev>
To: richard@....at,
	anton.ivanov@...bridgegreys.com,
	johannes@...solutions.net
Cc: linux-um@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	benjamin@...solutions.net,
	arnd@...db.de,
	tiwei.btw@...group.com,
	tiwei.bie@...ux.dev,
	Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH v3 5/7] um: vdso: Remove getcpu support on x86

From: Tiwei Bie <tiwei.btw@...group.com>

We are going to support SMP on UML/x86, so we can't hard code
the CPU and NUMA node in __vdso_getcpu() anymore. Let's just
remove it and let applications fall back to the syscall.

Suggested-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Tiwei Bie <tiwei.btw@...group.com>
---
 arch/x86/um/vdso/um_vdso.c  | 20 --------------------
 arch/x86/um/vdso/vdso.lds.S |  2 --
 2 files changed, 22 deletions(-)

diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index cbae2584124f..43a5ffcc7158 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -10,14 +10,12 @@
 #define DISABLE_BRANCH_PROFILING
 
 #include <linux/time.h>
-#include <linux/getcpu.h>
 #include <asm/unistd.h>
 
 /* workaround for -Wmissing-prototypes warnings */
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts);
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
 __kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
-long __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
 
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
@@ -58,21 +56,3 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 	return secs;
 }
 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
-
-long
-__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
-{
-	/*
-	 * UML does not support SMP, we can cheat here. :)
-	 */
-
-	if (cpu)
-		*cpu = 0;
-	if (node)
-		*node = 0;
-
-	return 0;
-}
-
-long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
-	__attribute__((weak, alias("__vdso_getcpu")));
diff --git a/arch/x86/um/vdso/vdso.lds.S b/arch/x86/um/vdso/vdso.lds.S
index 73c508587a98..401600effc0a 100644
--- a/arch/x86/um/vdso/vdso.lds.S
+++ b/arch/x86/um/vdso/vdso.lds.S
@@ -22,8 +22,6 @@ VERSION {
 		__vdso_clock_gettime;
 		gettimeofday;
 		__vdso_gettimeofday;
-		getcpu;
-		__vdso_getcpu;
 		time;
 		__vdso_time;
 	local: *;
-- 
2.34.1