[PATCH v2] arm64: Mark kernel as tainted on SAE and SError panic

[Breno Leitao <leitao@debian.org>]

Set TAINT_MACHINE_CHECK when SError or Synchronous External Abort (SEA)
interrupts trigger a panic to flag potential hardware faults. This
tainting mechanism aids in debugging and enables correlation of
hardware-related crashes in large-scale deployments.

This change aligns with similar patches[1] that mark machine check
events when the system crashes due to hardware errors.

Link: https://lore.kernel.org/all/20250702-add_tain-v1-1-9187b10914b9@debian.org/ [1]
Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v2:
- Also taint the kernel on Synchronous External Abort panics (Will Deacon)
- Link to v1: https://lore.kernel.org/r/20250714-vmcore_hw_error-v1-1-8cf45edb6334@debian.org
---
 arch/arm64/kernel/traps.c | 1 +
 arch/arm64/mm/fault.c     | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 9bfa5c944379d..7468b22585cef 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -931,6 +931,7 @@ void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigne
 
 void __noreturn arm64_serror_panic(struct pt_regs *regs, unsigned long esr)
 {
+	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_STILL_OK);
 	console_verbose();
 
 	pr_crit("SError Interrupt on CPU%d, code 0x%016lx -- %s\n",
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index ec0a337891ddf..004106ff4bd03 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -826,6 +826,7 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs)
 		 */
 		siaddr  = untagged_addr(far);
 	}
+	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_STILL_OK);
 	arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr);
 
 	return 0;

---
base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a
change-id: 20250707-vmcore_hw_error-322429e6c316

Best regards,
--  
Breno Leitao <leitao@debian.org>