[PATCH v2 0/7] um: A follow-up series of -Wmissing-prototypes fixes

[PATCH v2 0/7] um: A follow-up series of -Wmissing-prototypes fixes

[Tiwei Bie]

This is a follow-up series built on top of below series:
https://lore.kernel.org/linux-um/20240306101925.1088870-1-tiwei.btw@antgroup.com/

Changes since v1:
https://lore.kernel.org/linux-um/20240423112457.2409319-1-tiwei.btw@antgroup.com/
- include "internal.h" explicitly (Johannes);
- drop the "extern" (Johannes);

Tiwei Bie (7):
  um: Fix -Wmissing-prototypes warnings for (rt_)sigreturn
  um: Fix the -Wmissing-prototypes warning for __switch_mm
  um: Fix the -Wmissing-prototypes warning for get_thread_reg
  um: Fix the declaration of kasan_map_memory
  um: Add an internal header shared among the user code
  um: Fix -Wmissing-prototypes warnings for __vdso_*
  um: Remove unused do_get_thread_area function

 arch/um/include/asm/kasan.h             |  1 -
 arch/um/include/asm/mmu.h               |  2 --
 arch/um/include/asm/processor-generic.h |  1 -
 arch/um/include/shared/kern_util.h      |  2 ++
 arch/um/include/shared/skas/mm_id.h     |  2 ++
 arch/um/os-Linux/elf_aux.c              |  1 +
 arch/um/os-Linux/internal.h             | 20 ++++++++++++++++++++
 arch/um/os-Linux/main.c                 |  3 +--
 arch/um/os-Linux/mem.c                  |  2 ++
 arch/um/os-Linux/skas/mem.c             |  3 +--
 arch/um/os-Linux/skas/process.c         |  1 +
 arch/um/os-Linux/start_up.c             |  3 +--
 arch/x86/um/shared/sysdep/archsetjmp.h  |  7 +++++++
 arch/x86/um/signal.c                    |  5 +++--
 arch/x86/um/tls_32.c                    | 17 -----------------
 arch/x86/um/vdso/um_vdso.c              | 10 ++++++++--
 16 files changed, 49 insertions(+), 31 deletions(-)
 create mode 100644 arch/um/os-Linux/internal.h

-- 
2.34.1

[PATCH v2 1/7] um: Fix -Wmissing-prototypes warnings for (rt_)sigreturn

[Tiwei Bie]

Use SYSCALL_DEFINE0 to define (rt_)sigreturn. This will address
below -Wmissing-prototypes warnings:

arch/x86/um/signal.c:453:6: warning: no previous prototype for ‘sys_sigreturn’ [-Wmissing-prototypes]
arch/x86/um/signal.c:560:6: warning: no previous prototype for ‘sys_rt_sigreturn’ [-Wmissing-prototypes]

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/x86/um/signal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
index 263e1d08f216..48e87b45adba 100644
--- a/arch/x86/um/signal.c
+++ b/arch/x86/um/signal.c
@@ -8,6 +8,7 @@
 #include <linux/personality.h>
 #include <linux/ptrace.h>
 #include <linux/kernel.h>
+#include <linux/syscalls.h>
 #include <asm/unistd.h>
 #include <linux/uaccess.h>
 #include <asm/ucontext.h>
@@ -450,7 +451,7 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 	return 0;
 }
 
-long sys_sigreturn(void)
+SYSCALL_DEFINE0(sigreturn)
 {
 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
 	struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
@@ -557,7 +558,7 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 }
 #endif
 
-long sys_rt_sigreturn(void)
+SYSCALL_DEFINE0(rt_sigreturn)
 {
 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
 	struct rt_sigframe __user *frame =
-- 
2.34.1

[PATCH v2 2/7] um: Fix the -Wmissing-prototypes warning for __switch_mm

[Tiwei Bie]

The __switch_mm function is defined in the user code, and is called
by the kernel code. It should be declared in a shared header.

Fixes: 4dc706c2f292 ("um: take um_mmu.h to asm/mmu.h, clean asm/mmu_context.h a bit")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/include/asm/mmu.h           | 2 --
 arch/um/include/shared/skas/mm_id.h | 2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index a7555e43ed14..f2923c767bb9 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -14,8 +14,6 @@ typedef struct mm_context {
 	struct uml_arch_mm_context arch;
 } mm_context_t;
 
-extern void __switch_mm(struct mm_id * mm_idp);
-
 /* Avoid tangled inclusion with asm/ldt.h */
 extern long init_new_ldt(struct mm_context *to_mm, struct mm_context *from_mm);
 extern void free_ldt(struct mm_context *mm);
diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
index e82e203f5f41..92dbf727e384 100644
--- a/arch/um/include/shared/skas/mm_id.h
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -15,4 +15,6 @@ struct mm_id {
 	int kill;
 };
 
+void __switch_mm(struct mm_id *mm_idp);
+
 #endif
-- 
2.34.1

[PATCH v2 3/7] um: Fix the -Wmissing-prototypes warning for get_thread_reg

[Tiwei Bie]

The get_thread_reg function is defined in the user code, and is
called by the kernel code. It should be declared in a shared header.

Fixes: dbba7f704aa0 ("um: stop polluting the namespace with registers.h contents")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/include/asm/processor-generic.h | 1 -
 arch/x86/um/shared/sysdep/archsetjmp.h  | 7 +++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index 6c3779541845..5a7c05275aa7 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -94,7 +94,6 @@ extern struct cpuinfo_um boot_cpu_data;
 #define current_cpu_data boot_cpu_data
 #define cache_line_size()	(boot_cpu_data.cache_alignment)
 
-extern unsigned long get_thread_reg(int reg, jmp_buf *buf);
 #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
 extern unsigned long __get_wchan(struct task_struct *p);
 
diff --git a/arch/x86/um/shared/sysdep/archsetjmp.h b/arch/x86/um/shared/sysdep/archsetjmp.h
index 166cedbab926..8c81d1a604a9 100644
--- a/arch/x86/um/shared/sysdep/archsetjmp.h
+++ b/arch/x86/um/shared/sysdep/archsetjmp.h
@@ -1,6 +1,13 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_UM_SYSDEP_ARCHSETJMP_H
+#define __X86_UM_SYSDEP_ARCHSETJMP_H
+
 #ifdef __i386__
 #include "archsetjmp_32.h"
 #else
 #include "archsetjmp_64.h"
 #endif
+
+unsigned long get_thread_reg(int reg, jmp_buf *buf);
+
+#endif /* __X86_UM_SYSDEP_ARCHSETJMP_H */
-- 
2.34.1

[PATCH v2 4/7] um: Fix the declaration of kasan_map_memory

[Tiwei Bie]

Make it match its definition (size_t vs unsigned long). And declare
it in a shared header to fix the -Wmissing-prototypes warning, as it
is defined in the user code and called in the kernel code.

Fixes: 5b301409e8bc ("UML: add support for KASAN under x86_64")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/include/asm/kasan.h        | 1 -
 arch/um/include/shared/kern_util.h | 2 ++
 arch/um/os-Linux/mem.c             | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/um/include/asm/kasan.h b/arch/um/include/asm/kasan.h
index 0d6547f4ec85..f97bb1f7b851 100644
--- a/arch/um/include/asm/kasan.h
+++ b/arch/um/include/asm/kasan.h
@@ -24,7 +24,6 @@
 
 #ifdef CONFIG_KASAN
 void kasan_init(void);
-void kasan_map_memory(void *start, unsigned long len);
 extern int kasan_um_is_ready;
 
 #ifdef CONFIG_STATIC_LINK
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index 81bc38a2e3fc..95521b1f5b20 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -67,4 +67,6 @@ extern void fatal_sigsegv(void) __attribute__ ((noreturn));
 
 void um_idle_sleep(void);
 
+void kasan_map_memory(void *start, size_t len);
+
 #endif
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 8530b2e08604..c6c9495b1432 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -15,6 +15,7 @@
 #include <sys/vfs.h>
 #include <linux/magic.h>
 #include <init.h>
+#include <kern_util.h>
 #include <os.h>
 
 /*
-- 
2.34.1

[PATCH v2 5/7] um: Add an internal header shared among the user code

[Tiwei Bie]

Move relevant declarations to this header. This will address
below -Wmissing-prototypes warnings:

arch/um/os-Linux/elf_aux.c:26:13: warning: no previous prototype for ‘scan_elf_aux’ [-Wmissing-prototypes]
arch/um/os-Linux/mem.c:213:13: warning: no previous prototype for ‘check_tmpexec’ [-Wmissing-prototypes]
arch/um/os-Linux/skas/process.c:107:6: warning: no previous prototype for ‘wait_stub_done’ [-Wmissing-prototypes]

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/os-Linux/elf_aux.c      |  1 +
 arch/um/os-Linux/internal.h     | 20 ++++++++++++++++++++
 arch/um/os-Linux/main.c         |  3 +--
 arch/um/os-Linux/mem.c          |  1 +
 arch/um/os-Linux/skas/mem.c     |  3 +--
 arch/um/os-Linux/skas/process.c |  1 +
 arch/um/os-Linux/start_up.c     |  3 +--
 7 files changed, 26 insertions(+), 6 deletions(-)
 create mode 100644 arch/um/os-Linux/internal.h

diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c
index 344ac403fb5d..0a0f91cf4d6d 100644
--- a/arch/um/os-Linux/elf_aux.c
+++ b/arch/um/os-Linux/elf_aux.c
@@ -13,6 +13,7 @@
 #include <init.h>
 #include <elf_user.h>
 #include <mem_user.h>
+#include "internal.h"
 
 typedef Elf32_auxv_t elf_auxv_t;
 
diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
new file mode 100644
index 000000000000..317fca190c2b
--- /dev/null
+++ b/arch/um/os-Linux/internal.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_OS_LINUX_INTERNAL_H
+#define __UM_OS_LINUX_INTERNAL_H
+
+/*
+ * elf_aux.c
+ */
+void scan_elf_aux(char **envp);
+
+/*
+ * mem.c
+ */
+void check_tmpexec(void);
+
+/*
+ * skas/process.c
+ */
+void wait_stub_done(int pid);
+
+#endif /* __UM_OS_LINUX_INTERNAL_H */
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index e82164f90288..f98ff79cdbf7 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -16,6 +16,7 @@
 #include <kern_util.h>
 #include <os.h>
 #include <um_malloc.h>
+#include "internal.h"
 
 #define PGD_BOUND (4 * 1024 * 1024)
 #define STACKSIZE (8 * 1024 * 1024)
@@ -102,8 +103,6 @@ static void setup_env_path(void)
 	}
 }
 
-extern void scan_elf_aux( char **envp);
-
 int __init main(int argc, char **argv, char **envp)
 {
 	char **new_argv;
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index c6c9495b1432..cf44d386f23c 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -17,6 +17,7 @@
 #include <init.h>
 #include <kern_util.h>
 #include <os.h>
+#include "internal.h"
 
 /*
  * kasan_map_memory - maps memory from @start with a size of @len.
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index 953fb10f3f93..1f9c1bffc3a6 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -17,11 +17,10 @@
 #include <skas.h>
 #include <sysdep/ptrace.h>
 #include <sysdep/stub.h>
+#include "../internal.h"
 
 extern char batch_syscall_stub[], __syscall_stub_start[];
 
-extern void wait_stub_done(int pid);
-
 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
 					      unsigned long *stack)
 {
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 1f5c3f2523d1..41a288dcfc34 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -23,6 +23,7 @@
 #include <skas.h>
 #include <sysdep/stub.h>
 #include <linux/threads.h>
+#include "../internal.h"
 
 int is_skas_winch(int pid, int fd, void *data)
 {
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 6b21061c431c..89ad9f4f865c 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -25,6 +25,7 @@
 #include <ptrace_user.h>
 #include <registers.h>
 #include <skas.h>
+#include "internal.h"
 
 static void ptrace_child(void)
 {
@@ -222,8 +223,6 @@ static void __init check_ptrace(void)
 	check_sysemu();
 }
 
-extern void check_tmpexec(void);
-
 static void __init check_coredump_limit(void)
 {
 	struct rlimit lim;
-- 
2.34.1

[PATCH v2 6/7] um: Fix -Wmissing-prototypes warnings for __vdso_*

[Tiwei Bie]

The VDSO functions are defined as globals and intended to be called
from userspace. Let's just workaround the -Wmissing-prototypes warnings
by declaring them locally.

This will address below -Wmissing-prototypes warnings:

arch/x86/um/vdso/um_vdso.c:16:5: warning: no previous prototype for ‘__vdso_clock_gettime’ [-Wmissing-prototypes]
arch/x86/um/vdso/um_vdso.c:30:5: warning: no previous prototype for ‘__vdso_gettimeofday’ [-Wmissing-prototypes]
arch/x86/um/vdso/um_vdso.c:44:21: warning: no previous prototype for ‘__vdso_time’ [-Wmissing-prototypes]
arch/x86/um/vdso/um_vdso.c:57:1: warning: no previous prototype for ‘__vdso_getcpu’ [-Wmissing-prototypes]

While at it, also fix the "WARNING: Prefer 'unsigned int *' to bare
use of 'unsigned *'" checkpatch warning.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/x86/um/vdso/um_vdso.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index ff0f3b4b6c45..cbae2584124f 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -13,6 +13,12 @@
 #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)
 {
 	long ret;
@@ -54,7 +60,7 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
 
 long
-__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
 {
 	/*
 	 * UML does not support SMP, we can cheat here. :)
@@ -68,5 +74,5 @@ __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
 	return 0;
 }
 
-long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
+long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
 	__attribute__((weak, alias("__vdso_getcpu")));
-- 
2.34.1

[PATCH v2 7/7] um: Remove unused do_get_thread_area function

[Tiwei Bie]

It's not used since it was introduced by commit aa6758d4867c ("[PATCH]
uml: implement {get,set}_thread_area for i386"). Now, it's causing a
-Wmissing-prototypes warning:

arch/x86/um/tls_32.c:39:5: warning: no previous prototype for ‘do_get_thread_area’ [-Wmissing-prototypes]
   39 | int do_get_thread_area(struct user_desc *info)
      |     ^~~~~~~~~~~~~~~~~~

The original author also had doubts about whether it should be used.
Considering that 18 years have passed, let's just remove it.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/x86/um/tls_32.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/arch/x86/um/tls_32.c b/arch/x86/um/tls_32.c
index ba40b1b8e179..d301deee041f 100644
--- a/arch/x86/um/tls_32.c
+++ b/arch/x86/um/tls_32.c
@@ -36,22 +36,6 @@ static int do_set_thread_area(struct user_desc *info)
 	return ret;
 }
 
-int do_get_thread_area(struct user_desc *info)
-{
-	int ret;
-	u32 cpu;
-
-	cpu = get_cpu();
-	ret = os_get_thread_area(info, userspace_pid[cpu]);
-	put_cpu();
-
-	if (ret)
-		printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
-		       "index = %d\n", ret, info->entry_number);
-
-	return ret;
-}
-
 /*
  * sys_get_thread_area: get a yet unused TLS descriptor index.
  * XXX: Consider leaving one free slot for glibc usage at first place. This must
@@ -231,7 +215,6 @@ int arch_set_tls(struct task_struct *new, unsigned long tls)
 	return ret;
 }
 
-/* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */
 static int get_tls_entry(struct task_struct *task, struct user_desc *info,
 			 int idx)
 {
-- 
2.34.1