[PATCH v11 5/5] arm64: send SIGBUS to user process for SEA exception

[Tong Tiangen <tongtiangen@huawei.com>]

For SEA exception, kernel require take some action to recover from memory
error, such as isolate poison page adn kill failure thread, which are done
in memory_failure().

During the test, the failure thread cannot be killed due to this issue[1],
Here, I temporarily workaround this issue by sending signals to user
processes (!(PF_KTHREAD|PF_IO_WORKER|PF_WQ_WORKER|PF_USER_WORKER)) in
do_sea(). After [1] is merged, this patch can be rolled back or the SIGBUS
will be sent repeated.

[1]https://lore.kernel.org/lkml/20240204080144.7977-1-xueshuai@linux.alibaba.com/

Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
---
 arch/arm64/mm/fault.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 78f9d5ce83bb..a27bb2de1a7c 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -824,9 +824,6 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs)
 	const struct fault_info *inf;
 	unsigned long siaddr;
 
-	if (do_apei_claim_sea(regs))
-		return 0;
-
 	inf = esr_to_fault_info(esr);
 	if (esr & ESR_ELx_FnV) {
 		siaddr = 0;
@@ -838,6 +835,19 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs)
 		 */
 		siaddr  = untagged_addr(far);
 	}
+
+	if (do_apei_claim_sea(regs)) {
+		if (!(current->flags & (PF_KTHREAD |
+					PF_USER_WORKER |
+					PF_WQ_WORKER |
+					PF_IO_WORKER))) {
+			set_thread_esr(0, esr);
+			arm64_force_sig_fault(inf->sig, inf->code, siaddr,
+				"Uncorrected memory error on access to poison memory\n");
+		}
+		return 0;
+	}
+
 	arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr);
 
 	return 0;
-- 
2.25.1