[PATCH] arm64: Print provenance information for addresses in registers

[Stefan Wiehler]

Like commit 5aa6b70ed182 ("arm: print alloc free paths for address in
registers") already does for 32-bit ARM, print available provenance information
for addresses in registers in case of internal error as a debugging aid:

  Unable to handle kernel write to read-only memory at virtual address ffffffc00117cd5c
  ...
  x2 : 0000000000001b98 x1 : 0000000000000000 x0 : ffffffc00117cd5c
  ...
  Register x0 information: 14-page vmalloc region starting at 0xffffffc00117a000 allocated at load_module+0x15c4/0x2bc0
  Register x1 information: NULL pointer
  Register x2 information: non-paged memory
  ...

Signed-off-by: Stefan Wiehler <stefan.wiehler@xxxxxxxxx>
---
 arch/arm64/include/asm/system_misc.h |  1 +
 arch/arm64/kernel/process.c          | 11 +++++++++++
 arch/arm64/kernel/traps.c            |  1 +
 3 files changed, 13 insertions(+)

diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
index c34344256762..5b9b02fee988 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -31,6 +31,7 @@ void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned long,
 
 struct mm_struct;
 extern void __show_regs(struct pt_regs *);
+extern void __show_regs_alloc_free(struct pt_regs *);
 
 #endif	/* __ASSEMBLY__ */
 
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7387b68c745b..b6fc2ac6e007 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -197,6 +197,17 @@ static void print_pstate(struct pt_regs *regs)
 	}
 }
 
+void __show_regs_alloc_free(struct pt_regs *regs)
+{
+	int i;
+
+	/* check for x0 - x29 only */
+	for (i = 0; i < 30; i++) {
+		pr_alert("Register x%d information:", i);
+		mem_dump_obj((void *)regs->regs[i]);
+	}
+}
+
 void __show_regs(struct pt_regs *regs)
 {
 	int i, top_reg;
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 215e6d7f2df8..b7bf22f1b33f 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -197,6 +197,7 @@ static int __die(const char *str, long err, struct pt_regs *regs)
 
 	print_modules();
 	show_regs(regs);
+	__show_regs_alloc_free(regs);
 
 	dump_kernel_instr(KERN_EMERG, regs);
 
-- 
2.42.0