s390: use get_user()/put_user() instead of the unchecked variants

bb4e937f · Linus Torvalds <[email protected]> · 2026-10-20 09:55:28 -10:00

On s390 user space is a separate address space, so access_ok() has
nothing to check, and get_user() and put_user() are __get_user() and
__put_user() plus might_fault().  The remaining callers can use the
normal accessors directly:

 - signal frame setup writes the back chain, the signal number and the
   ucontext header in process context;

 - the user stack walker for stack traces and perf callchains already
   runs under pagefault_disable(), where might_fault() returns early;

 - the general register set writer for ptrace runs in the tracer's
   process context with no locks held.

This is part of getting rid of __get_user() and __put_user() entirely.

Signed-off-by: Linus Torvalds <[email protected]>

Commit: bb4e937ff6857ca9277d35683682ea4c1f75ff2a
Parents: 48e59591

Changes

3 files changed · +10 −10

File	Status	Add	Del	Content
arch/s390/kernel/ptrace.c	modified	+1	−1	View file
arch/s390/kernel/signal.c	modified	+5	−5	View file
arch/s390/kernel/stacktrace.c	modified	+4	−4	View file

arch/s390/kernel/ptrace.c

View file

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 125ca4c..06c6901 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -540,7 +540,7 @@ static int s390_regs_set(struct task_struct *target,
 		const unsigned long  __user *u = ubuf;
 		while (count > 0 && !rc) {
 			unsigned long word;
-			rc = __get_user(word, u++);
+			rc = get_user(word, u++);
 			if (rc)
 				break;
 			rc = __poke_user(target, pos, word);

arch/s390/kernel/signal.c

View file

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4874de5..81709cd 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -297,7 +297,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
 		return -EFAULT;
 
 	/* Set up backchain. */
-	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
+	if (put_user(regs->gprs[15], (addr_t __user *) frame))
 		return -EFAULT;
 
 	/* Create struct sigcontext on the signal stack */
@@ -314,7 +314,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
 		return -EFAULT;
 
 	/* Place signal number on stack to allow backtrace from handler.  */
-	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
+	if (put_user(regs->gprs[2], (int __user *) &frame->signo))
 		return -EFAULT;
 
 	/* Create _sigregs_ext on the signal stack */
@@ -370,7 +370,7 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 		return -EFAULT;
 
 	/* Set up backchain. */
-	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
+	if (put_user(regs->gprs[15], (addr_t __user *) frame))
 		return -EFAULT;
 
 	/* Set up to return from userspace.  If provided, use a stub
@@ -388,8 +388,8 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 	store_sigregs();
 
 	/* Create ucontext on the signal stack. */
-	if (__put_user(uc_flags, &frame->uc.uc_flags) ||
-	    __put_user(NULL, &frame->uc.uc_link) ||
+	if (put_user(uc_flags, &frame->uc.uc_flags) ||
+	    put_user(NULL, &frame->uc.uc_link) ||
 	    __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
 	    save_sigregs(regs, &frame->uc.uc_mcontext) ||
 	    __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||

arch/s390/kernel/stacktrace.c

View file

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 18520d3..191f8a9 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -113,7 +113,7 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
 	sf = (void __user *)user_stack_pointer(regs);
 	pagefault_disable();
 	while (1) {
-		if (__get_user(sp, &sf->back_chain))
+		if (get_user(sp, &sf->back_chain))
 			break;
 		/*
 		 * VDSO entry code has a non-standard stack frame layout.
@@ -121,15 +121,15 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
 		 */
 		if (!sp && ip_within_vdso(ip)) {
 			sf_vdso = (void __user *)sf;
-			if (__get_user(ip, &sf_vdso->return_address))
+			if (get_user(ip, &sf_vdso->return_address))
 				break;
 			sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD;
 			sf = (void __user *)sp;
-			if (__get_user(sp, &sf->back_chain))
+			if (get_user(sp, &sf->back_chain))
 				break;
 		} else {
 			sf = (void __user *)sp;
-			if (__get_user(ip, &sf->gprs[8]))
+			if (get_user(ip, &sf->gprs[8]))
 				break;
 		}
 		/* Validate SP and RA (ABI requires SP to be 8 byte aligned). */