LoongArch: Add kernel livepatching support

The arch-specified function ftrace_regs_set_instruction_pointer() has
been implemented in arch/loongarch/include/asm/ftrace.h, so here only
implement arch_stack_walk_reliable() function.

Here are the test logs:

[root@linux fedora]# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-6.8.0-rc2 root=/dev/sda3

[root@linux fedora]# modprobe livepatch-sample
[root@linux fedora]# cat /proc/cmdline
this has been live patched

[root@linux fedora]# echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
[root@linux fedora]# rmmod livepatch_sample
[root@linux fedora]# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-6.8.0-rc2 root=/dev/sda3

[root@linux fedora]# dmesg -t | tail -5
livepatch: enabling patch 'livepatch_sample'
livepatch: 'livepatch_sample': starting patching transition
livepatch: 'livepatch_sample': patching complete
livepatch: 'livepatch_sample': starting unpatching transition
livepatch: 'livepatch_sample': unpatching complete

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 8d6725115ac6bda9ec4b9f73d7f68045c07c314b..99a0a15ce5f7c0cd92b62cd743cdf96a21b8acbc 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -134,6 +134,7 @@ config LOONGARCH
        select HAVE_KPROBES_ON_FTRACE
        select HAVE_KRETPROBES
        select HAVE_KVM
+       select HAVE_LIVEPATCH
        select HAVE_MOD_ARCH_SPECIFIC
        select HAVE_NMI
        select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
@@ -143,6 +144,7 @@ config LOONGARCH
        select HAVE_PERF_USER_STACK_DUMP
        select HAVE_PREEMPT_DYNAMIC_KEY
        select HAVE_REGS_AND_STACK_ACCESS_API
+       select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC
        select HAVE_RETHOOK
        select HAVE_RSEQ
        select HAVE_RUST
@@ -636,6 +638,8 @@ config RANDOMIZE_BASE_MAX_OFFSET
 
          This is limited by the size of the lower address memory, 256MB.
 
+source "kernel/livepatch/Kconfig"
+
 endmenu
 
 config ARCH_SELECT_MEMORY_MODEL

diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
index 8cb653d49a54343ebfa26814e037ddf844c98351..8bf0e6f5154668e7ea477e5182d68705ab4a4f32 100644 (file)
--- a/arch/loongarch/include/asm/thread_info.h
+++ b/arch/loongarch/include/asm/thread_info.h
@@ -86,6 +86,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
 #define TIF_LASX_CTX_LIVE      18      /* LASX context must be preserved */
 #define TIF_USEDLBT            19      /* LBT was used by this task this quantum (SMP) */
 #define TIF_LBT_CTX_LIVE       20      /* LBT context must be preserved */
+#define TIF_PATCH_PENDING      21      /* pending live patching update */
 
 #define _TIF_SIGPENDING                (1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED      (1<<TIF_NEED_RESCHED)
@@ -105,6 +106,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
 #define _TIF_LASX_CTX_LIVE     (1<<TIF_LASX_CTX_LIVE)
 #define _TIF_USEDLBT           (1<<TIF_USEDLBT)
 #define _TIF_LBT_CTX_LIVE      (1<<TIF_LBT_CTX_LIVE)
+#define _TIF_PATCH_PENDING     (1<<TIF_PATCH_PENDING)
 
 #endif /* __KERNEL__ */
 #endif /* _ASM_THREAD_INFO_H */

diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index eaec82e02c92abe43597dd6ad246834a01c2c2e7..9a038d1070d73b1efcf195ea7ba02e574bca104a 100644 (file)
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -40,6 +40,46 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
        }
 }
 
+int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
+                            void *cookie, struct task_struct *task)
+{
+       unsigned long addr;
+       struct pt_regs dummyregs;
+       struct pt_regs *regs = &dummyregs;
+       struct unwind_state state;
+
+       if (task == current) {
+               regs->regs[3] = (unsigned long)__builtin_frame_address(0);
+               regs->csr_era = (unsigned long)__builtin_return_address(0);
+       } else {
+               regs->regs[3] = thread_saved_fp(task);
+               regs->csr_era = thread_saved_ra(task);
+       }
+       regs->regs[1] = 0;
+       regs->regs[22] = 0;
+
+       for (unwind_start(&state, task, regs);
+            !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
+               addr = unwind_get_return_address(&state);
+
+               /*
+                * A NULL or invalid return address probably means there's some
+                * generated code which __kernel_text_address() doesn't know about.
+                */
+               if (!addr)
+                       return -EINVAL;
+
+               if (!consume_entry(cookie, addr))
+                       return -EINVAL;
+       }
+
+       /* Check for stack corruption */
+       if (unwind_error(&state))
+               return -EINVAL;
+
+       return 0;
+}
+
 static int
 copy_stack_frame(unsigned long fp, struct stack_frame *frame)
 {