linux-kernel - [PATCH v2] arm/stacktrace: stop unwinding after an invalid address.

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Date:   Wed, 21 Mar 2018 16:40:45 +0530
From:   Maninder Singh <maninder1.s@...sung.com>
To:     linux@...linux.org.uk, dustinb@...eaurora.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        a.sahrawat@...sung.com, pankaj.m@...sung.com,
        Maninder Singh <maninder1.s@...sung.com>,
        Vaneet Narang <v.narang@...sung.com>
Subject: [PATCH v2] arm/stacktrace: stop unwinding after an invalid address.

This patch stops unwinding backtrace in case address does not
belong to kernel address like below:-

....
__do_fault+0x4c/0xa8
handle_mm_fault+0xb74/0x11c0
do_page_fault+0x29c/0x38c
do_DataAbort+0x40/0xb8
__dabt_usr+0x44/0x60
0xb6748ea4
^^^^^^^^

So this patch discards last junk entry.

Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
Signed-off-by: Vaneet Narang <v.narang@...sung.com>
---
v1->v2: https://lkml.org/lkml/2017/10/24/378
(take care of IRQ taken in SVC mode)

 arch/arm/kernel/stacktrace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index a56e7c8..1aadffc 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -92,6 +92,9 @@ static int save_trace(struct stackframe *frame, void *d)
 
 	regs = (struct pt_regs *)frame->sp;
 
+	if (!__kernel_text_address(regs->ARM_pc))
+		return 1;
+
 	trace->entries[trace->nr_entries++] = regs->ARM_pc;
 
 	return trace->nr_entries >= trace->max_entries;
-- 
1.9.1