From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
Cc: Ard Biesheuvel <ardb@kernel.org>,
Corentin Labbe <clabbe.montjoie@gmail.com>
Subject: [PATCH] ARM: unwind: avoid spurious warnings on bogus code addresses
Date: Tue, 1 Mar 2022 23:05:36 +0100 [thread overview]
Message-ID: <20220301220536.1302898-1-ardb@kernel.org> (raw)
Corentin reports that since commit 538b9265c063 ("ARM: unwind: track
location of LR value in stack frame"), numerous spurious warnings are
emitted into the kernel log:
[ 0.000000] unwind: Index not found c0f0c440
[ 0.000000] unwind: Index not found 00000000
[ 0.000000] unwind: Index not found c0f0c440
[ 0.000000] unwind: Index not found 00000000
This is due to the fact that the commit in question removes a check
whether the PC value in the unwound frame is actually a kernel text
address, on the assumption that such an address will not be associated
with valid unwind data to begin with, which is checked right after.
The reason for removing this check was that unwind_frame() will be
called by the ftrace graph tracer code, which means that it can no
longer be safely instrumented itself, or any code that it calls, as it
could cause infinite recursion.
In order to prevent the spurious diagnostics, let's add back the call to
kernel_text_address(), but this time, only call it if no unwind data
could be found for the address in question. This is more efficient for
the common successful case, and should avoid any unintended recursion,
considering that kernel_text_address() will only be called if no unwind
data was found.
Cc: Corentin Labbe <clabbe.montjoie@gmail.com>
Fixes: 538b9265c063 ("ARM: unwind: track location of LR value in stack frame")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm/kernel/unwind.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index b4e468a7674b..04ccff9d9793 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -400,7 +400,8 @@ int unwind_frame(struct stackframe *frame)
idx = unwind_find_idx(frame->pc);
if (!idx) {
- pr_warn("unwind: Index not found %08lx\n", frame->pc);
+ if (frame->pc && kernel_text_address(frame->pc))
+ pr_warn("unwind: Index not found %08lx\n", frame->pc);
return -URC_FAILURE;
}
--
2.30.2
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
reply other threads:[~2022-03-01 22:07 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220301220536.1302898-1-ardb@kernel.org \
--to=ardb@kernel.org \
--cc=clabbe.montjoie@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux@armlinux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).