linux-kernel - [PATCH 2/2] arm64: Implement HAVE

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Message-ID: <20250308012742.3208215-3-song@kernel.org>
Date: Fri,  7 Mar 2025 17:27:42 -0800
From: Song Liu <song@...nel.org>
To: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-toolchains@...r.kernel.org,
	live-patching@...r.kernel.org
Cc: indu.bhagat@...cle.com,
	puranjay@...nel.org,
	wnliu@...gle.com,
	irogers@...gle.com,
	joe.lawrence@...hat.com,
	jpoimboe@...nel.org,
	mark.rutland@....com,
	peterz@...radead.org,
	roman.gushchin@...ux.dev,
	rostedt@...dmis.org,
	will@...nel.org,
	kernel-team@...a.com,
	song@...nel.org,
	Suraj Jitindar Singh <surajjs@...zon.com>,
	Torsten Duwe <duwe@...e.de>
Subject: [PATCH 2/2] arm64: Implement HAVE_LIVEPATCH

This is largely based on [1] by Suraj Jitindar Singh.

Test coverage:

- Passed manual tests with samples/livepatch.
- Passed all but test-kprobe.sh in selftests/livepatch.
  test-kprobe.sh is expected to fail, because arm64 doesn't have
  KPROBES_ON_FTRACE.
- Passed tests with kpatch-build [2]. (This version includes commits that
  are not merged to upstream kpatch yet).

[1] https://lore.kernel.org/all/20210604235930.603-1-surajjs@amazon.com/
[2] https://github.com/liu-song-6/kpatch/tree/fb-6.13
Cc: Suraj Jitindar Singh <surajjs@...zon.com>
Cc: Torsten Duwe <duwe@...e.de>
Signed-off-by: Song Liu <song@...nel.org>
---
 arch/arm64/Kconfig                   | 3 +++
 arch/arm64/include/asm/thread_info.h | 4 +++-
 arch/arm64/kernel/entry-common.c     | 4 ++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index ed4f7bf4a879..bc9edba6171a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -276,6 +276,7 @@ config ARM64
 	select USER_STACKTRACE_SUPPORT
 	select VDSO_GETRANDOM
 	select HAVE_RELIABLE_STACKTRACE
+	select HAVE_LIVEPATCH
 	help
 	  ARM 64-bit (AArch64) Linux support.
 
@@ -2500,3 +2501,5 @@ endmenu # "CPU Power Management"
 source "drivers/acpi/Kconfig"
 
 source "arch/arm64/kvm/Kconfig"
+
+source "kernel/livepatch/Kconfig"
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 1114c1c3300a..4ac42e13032b 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -64,6 +64,7 @@ void arch_setup_new_exec(void);
 #define TIF_UPROBE		4	/* uprobe breakpoint or singlestep */
 #define TIF_MTE_ASYNC_FAULT	5	/* MTE Asynchronous Tag Check Fault */
 #define TIF_NOTIFY_SIGNAL	6	/* signal notifications exist */
+#define TIF_PATCH_PENDING	7	/* pending live patching update */
 #define TIF_SYSCALL_TRACE	8	/* syscall trace active */
 #define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
 #define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
@@ -92,6 +93,7 @@ void arch_setup_new_exec(void);
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
+#define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_32BIT		(1 << TIF_32BIT)
@@ -103,7 +105,7 @@ void arch_setup_new_exec(void);
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
 				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
-				 _TIF_NOTIFY_SIGNAL)
+				 _TIF_NOTIFY_SIGNAL | _TIF_PATCH_PENDING)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index b260ddc4d3e9..b537af333b42 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -8,6 +8,7 @@
 #include <linux/context_tracking.h>
 #include <linux/kasan.h>
 #include <linux/linkage.h>
+#include <linux/livepatch.h>
 #include <linux/lockdep.h>
 #include <linux/ptrace.h>
 #include <linux/resume_user_mode.h>
@@ -144,6 +145,9 @@ static void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 				       (void __user *)NULL, current);
 		}
 
+		if (thread_flags & _TIF_PATCH_PENDING)
+			klp_update_patch_state(current);
+
 		if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 			do_signal(regs);
 
-- 
2.43.5