Re: [PATCH v3 2/2] arm64: Implement HAVE_LIVEPATCH

Andrea della Porta
2025-03-31T09:05:57Z

On 10:15 Thu 20 Mar , Song Liu wrote:
> 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@amazon.com>
> Cc: Torsten Duwe <duwe@suse.de>
> Signed-off-by: Song Liu <song@kernel.org>
> Acked-by: Miroslav Benes <mbenes@suse.cz>
> Tested-by: Breno Leitao <leitao@debian.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 31d5e1ee6089..dbd237b13b21 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -277,6 +277,7 @@ config ARM64
> select USER_STACKTRACE_SUPPORT
> select VDSO_GETRANDOM
> select HAVE_RELIABLE_STACKTRACE
> + select HAVE_LIVEPATCH
> help
> ARM 64-bit (AArch64) Linux support.
>
> @@ -2501,3 +2502,5 @@ 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);
>
> --
> 2.47.1
>

Tested-by: Andrea della Porta <andrea.porta@suse.com>

Thanks,
Andrea