[PATCH v5 3/7] arch/*/uprobes: simplify arch_uretprobe_hijack_return_addr

[Andrzej Hajda <andrzej.hajda@xxxxxxxxx>]

In all architectures, except x86, arch_uretprobe_hijack_return_addr
is just __xchg.

Signed-off-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
---
 arch/arm/probes/uprobes/core.c     |  8 ++------
 arch/arm64/kernel/probes/uprobes.c |  9 ++-------
 arch/csky/kernel/probes/uprobes.c  |  9 ++-------
 arch/mips/kernel/uprobes.c         | 10 ++--------
 arch/powerpc/kernel/uprobes.c      | 10 ++--------
 arch/riscv/kernel/probes/uprobes.c |  9 ++-------
 arch/s390/kernel/uprobes.c         |  7 ++-----
 arch/sparc/kernel/uprobes.c        |  7 ++-----
 8 files changed, 16 insertions(+), 53 deletions(-)

diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c
index f5f790c6e5f896..77ce8ae431376d 100644
--- a/arch/arm/probes/uprobes/core.c
+++ b/arch/arm/probes/uprobes/core.c
@@ -9,6 +9,7 @@
 #include <linux/highmem.h>
 #include <linux/sched.h>
 #include <linux/uprobes.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/notifier.h>
 
 #include <asm/opcodes.h>
@@ -61,12 +62,7 @@ unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 				  struct pt_regs *regs)
 {
-	unsigned long orig_ret_vaddr;
-
-	orig_ret_vaddr = regs->ARM_lr;
-	/* Replace the return addr with trampoline addr */
-	regs->ARM_lr = trampoline_vaddr;
-	return orig_ret_vaddr;
+	return __xchg(&regs->ARM_lr, trampoline_vaddr);
 }
 
 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c
index d49aef2657cdf7..d7171d30ea6681 100644
--- a/arch/arm64/kernel/probes/uprobes.c
+++ b/arch/arm64/kernel/probes/uprobes.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2014-2016 Pratyush Anand <panand@xxxxxxxxxx>
  */
 #include <linux/highmem.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/ptrace.h>
 #include <linux/uprobes.h>
 #include <asm/cacheflush.h>
@@ -150,13 +151,7 @@ unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 				  struct pt_regs *regs)
 {
-	unsigned long orig_ret_vaddr;
-
-	orig_ret_vaddr = procedure_link_pointer(regs);
-	/* Replace the return addr with trampoline addr */
-	procedure_link_pointer_set(regs, trampoline_vaddr);
-
-	return orig_ret_vaddr;
+	return __xchg(&procedure_link_pointer(regs), trampoline_vaddr);
 }
 
 int arch_uprobe_exception_notify(struct notifier_block *self,
diff --git a/arch/csky/kernel/probes/uprobes.c b/arch/csky/kernel/probes/uprobes.c
index 2d31a12e46cfee..775fe88b5f0016 100644
--- a/arch/csky/kernel/probes/uprobes.c
+++ b/arch/csky/kernel/probes/uprobes.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2014-2016 Pratyush Anand <panand@xxxxxxxxxx>
  */
 #include <linux/highmem.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/ptrace.h>
 #include <linux/uprobes.h>
 #include <asm/cacheflush.h>
@@ -123,13 +124,7 @@ unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 				  struct pt_regs *regs)
 {
-	unsigned long ra;
-
-	ra = regs->lr;
-
-	regs->lr = trampoline_vaddr;
-
-	return ra;
+	return __xchg(&regs->lr, trampoline_vaddr);
 }
 
 int arch_uprobe_exception_notify(struct notifier_block *self,
diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c
index 6c063aa188e626..2b1f375c407b87 100644
--- a/arch/mips/kernel/uprobes.c
+++ b/arch/mips/kernel/uprobes.c
@@ -2,6 +2,7 @@
 #include <linux/highmem.h>
 #include <linux/kdebug.h>
 #include <linux/types.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/notifier.h>
 #include <linux/sched.h>
 #include <linux/uprobes.h>
@@ -197,14 +198,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *aup,
 unsigned long arch_uretprobe_hijack_return_addr(
 	unsigned long trampoline_vaddr, struct pt_regs *regs)
 {
-	unsigned long ra;
-
-	ra = regs->regs[31];
-
-	/* Replace the return address with the trampoline address */
-	regs->regs[31] = trampoline_vaddr;
-
-	return ra;
+	return __xchg(&regs->regs[31], trampoline_vaddr);
 }
 
 /**
diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index 95a41ae9dfa755..3c15c320315e6c 100644
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c
@@ -7,6 +7,7 @@
  * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
  */
 #include <linux/kernel.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/sched.h>
 #include <linux/ptrace.h>
 #include <linux/uprobes.h>
@@ -197,14 +198,7 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs)
 {
-	unsigned long orig_ret_vaddr;
-
-	orig_ret_vaddr = regs->link;
-
-	/* Replace the return addr with trampoline addr */
-	regs->link = trampoline_vaddr;
-
-	return orig_ret_vaddr;
+	return __xchg(&regs->link, trampoline_vaddr);
 }
 
 bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
diff --git a/arch/riscv/kernel/probes/uprobes.c b/arch/riscv/kernel/probes/uprobes.c
index c976a21cd4bd5b..5c8415e216536d 100644
--- a/arch/riscv/kernel/probes/uprobes.c
+++ b/arch/riscv/kernel/probes/uprobes.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
 #include <linux/highmem.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/ptrace.h>
 #include <linux/uprobes.h>
 
@@ -122,13 +123,7 @@ unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 				  struct pt_regs *regs)
 {
-	unsigned long ra;
-
-	ra = regs->ra;
-
-	regs->ra = trampoline_vaddr;
-
-	return ra;
+	return __xchg(&regs->ra, trampoline_vaddr);
 }
 
 int arch_uprobe_exception_notify(struct notifier_block *self,
diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c
index b88345ef8bd9ed..18591ca40ae7e5 100644
--- a/arch/s390/kernel/uprobes.c
+++ b/arch/s390/kernel/uprobes.c
@@ -11,6 +11,7 @@
 #include <linux/compat.h>
 #include <linux/kdebug.h>
 #include <linux/sched/task_stack.h>
+#include <linux/non-atomic/xchg.h>
 
 #include <asm/switch_to.h>
 #include <asm/facility.h>
@@ -144,11 +145,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
 						struct pt_regs *regs)
 {
-	unsigned long orig;
-
-	orig = regs->gprs[14];
-	regs->gprs[14] = trampoline;
-	return orig;
+	return __xchg(&regs->gprs[14], trampoline);
 }
 
 bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
diff --git a/arch/sparc/kernel/uprobes.c b/arch/sparc/kernel/uprobes.c
index 1a0600206bf5c2..1c02653d6de3ba 100644
--- a/arch/sparc/kernel/uprobes.c
+++ b/arch/sparc/kernel/uprobes.c
@@ -11,6 +11,7 @@
 
 #include <linux/kernel.h>
 #include <linux/highmem.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/uprobes.h>
 #include <linux/uaccess.h>
 #include <linux/sched.h> /* For struct task_struct */
@@ -310,9 +311,5 @@ unsigned long
 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 				  struct pt_regs *regs)
 {
-	unsigned long orig_ret_vaddr = regs->u_regs[UREG_I7];
-
-	regs->u_regs[UREG_I7] = trampoline_vaddr-8;
-
-	return orig_ret_vaddr + 8;
+	return __xchg(&regs->u_regs[UREG_I7], trampoline_vaddr - 8) + 8;
 }
-- 
2.34.1