vdso: Remove struct getcpu_cache

The cache parameter of getcpu() is useless nowadays for various reasons.

  * It is never passed by userspace for either the vDSO or syscalls.
  * It is never used by the kernel.
  * It could not be made to work on the current vDSO architecture.
  * The structure definition is not part of the UAPI headers.
  * vdso_getcpu() is superseded by restartable sequences in any case.

Remove the struct and its header.

As a side-effect this gets rid of an unwanted inclusion of the linux/
header namespace from vDSO code.

[ tglx: Adapt to s390 upstream changes */

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Link: https://patch.msgid.link/20251230-getcpu_cache-v3-1-fb9c5f880ebe@linutronix.de

Author: t-8ch

arch/loongarch/vdso/vgetcpu.c

@@ -4,7 +4,6 @@
  */
 
 #include <asm/vdso.h>
-#include <linux/getcpu.h>
 
 static __always_inline int read_cpu_id(void)
 {
@@ -28,8 +27,8 @@ static __always_inline int read_cpu_id(void)
 }
 
 extern
-int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
-int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
+int __vdso_getcpu(unsigned int *cpu, unsigned int *node, void *unused);
+int __vdso_getcpu(unsigned int *cpu, unsigned int *node, void *unused)
 {
 	int cpu_id;
 

arch/s390/kernel/vdso/getcpu.c

@@ -2,11 +2,10 @@
 /* Copyright IBM Corp. 2020 */
 
 #include <linux/compiler.h>
-#include <linux/getcpu.h>
 #include <asm/timex.h>
 #include "vdso.h"
 
-int __s390_vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+int __s390_vdso_getcpu(unsigned *cpu, unsigned *node, void *unused)
 {
 	union tod_clock clk;
 

arch/s390/kernel/vdso/vdso.h

@@ -4,9 +4,7 @@
 
 #include <vdso/datapage.h>
 
-struct getcpu_cache;
-
-int __s390_vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused);
+int __s390_vdso_getcpu(unsigned *cpu, unsigned *node, void *unused);
 int __s390_vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
 int __s390_vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
 int __s390_vdso_clock_getres(clockid_t clock, struct __kernel_timespec *ts);

arch/x86/entry/vdso/vgetcpu.c

@@ -6,17 +6,16 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/getcpu.h>
 #include <asm/segment.h>
 #include <vdso/processor.h>
 
 notrace long
-__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+__vdso_getcpu(unsigned *cpu, unsigned *node, void *unused)
 {
 	vdso_read_cpunode(cpu, node);
 
 	return 0;
 }
 
-long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
+long getcpu(unsigned *cpu, unsigned *node, void *tcache)
 	__attribute__((weak, alias("__vdso_getcpu")));

arch/x86/include/asm/vdso/processor.h

@@ -18,9 +18,7 @@ static __always_inline void cpu_relax(void)
 	native_pause();
 }
 
-struct getcpu_cache;
-
-notrace long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused);
+notrace long __vdso_getcpu(unsigned *cpu, unsigned *node, void *unused);
 
 #endif /* __ASSEMBLER__ */
 

include/linux/getcpu.h

@@ -59,7 +59,6 @@ struct compat_stat;
 struct old_timeval32;
 struct robust_list_head;
 struct futex_waitv;
-struct getcpu_cache;
 struct old_linux_dirent;
 struct perf_event_attr;
 struct file_handle;
@@ -718,7 +717,7 @@ asmlinkage long sys_getrusage(int who, struct rusage __user *ru);
 asmlinkage long sys_umask(int mask);
 asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
 			unsigned long arg4, unsigned long arg5);
-asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct getcpu_cache __user *cache);
+asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, void __user *cache);
 asmlinkage long sys_gettimeofday(struct __kernel_old_timeval __user *tv,
 				struct timezone __user *tz);
 asmlinkage long sys_settimeofday(struct __kernel_old_timeval __user *tv,

include/linux/syscalls.h

@@ -31,7 +31,6 @@
 #include <linux/tty.h>
 #include <linux/signal.h>
 #include <linux/cn_proc.h>
-#include <linux/getcpu.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/seccomp.h>
 #include <linux/cpu.h>
@@ -2876,8 +2875,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 	return error;
 }
 
-SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
-		struct getcpu_cache __user *, unused)
+SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep, void __user *, unused)
 {
 	int err = 0;
 	int cpu = raw_smp_processor_id();

kernel/sys.c

@@ -16,9 +16,7 @@
 #include "vdso_config.h"
 #include "vdso_call.h"
 
-struct getcpu_cache;
-typedef long (*getcpu_t)(unsigned int *, unsigned int *,
-			 struct getcpu_cache *);
+typedef long (*getcpu_t)(unsigned int *, unsigned int *, void *);
 
 int main(int argc, char **argv)
 {