arm64: Mark kernel as tainted on SAE and SError panic

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>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250716-vmcore_hw_error-v2-1-f187f7d62aba@debian.org
Signed-off-by: Will Deacon <will@kernel.org>

Author: leitao

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",

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;