linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Peter Collingbourne <pcc@google.com>
To: Mark Brown <broonie@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Andrey Konovalov <andreyknvl@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Ard Biesheuvel <ardb@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: [PATCH v3 2/3] arm64: stacktrace: Relax frame record alignment requirement to 8 bytes
Date: Wed,  2 Dec 2020 21:12:23 -0800	[thread overview]
Message-ID: <41a146c68cdd682dfee51ef881114dd5c809f2ec.1606972188.git.pcc@google.com> (raw)
In-Reply-To: <01b1819ec213797c9cd44bc23a9e9641f3bb64b2.1606972188.git.pcc@google.com>

The AAPCS places no requirements on the alignment of the frame
record. In theory it could be placed anywhere, although it seems
sensible to require it to be aligned to 8 bytes. With an upcoming
enhancement to tag-based KASAN Clang will begin creating frame records
located at an address that is only aligned to 8 bytes. Accommodate
such frame records in the stack unwinding code.

As pointed out by Mark Rutland, the userspace stack unwinding code
has the same problem, so fix it there as well.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ia22c375230e67ca055e9e4bb639383567f7ad268
Acked-by: Andrey Konovalov <andreyknvl@google.com>
---
v2:
- fix it in the userspace unwinding code as well

 arch/arm64/kernel/perf_callchain.c | 2 +-
 arch/arm64/kernel/stacktrace.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 88ff471b0bce..4a72c2727309 100644
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -116,7 +116,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 		tail = (struct frame_tail __user *)regs->regs[29];
 
 		while (entry->nr < entry->max_stack &&
-		       tail && !((unsigned long)tail & 0xf))
+		       tail && !((unsigned long)tail & 0x7))
 			tail = user_backtrace(tail, entry);
 	} else {
 #ifdef CONFIG_COMPAT
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ce613e22b58b..3bc1c44b7910 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -44,7 +44,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
 	unsigned long fp = frame->fp;
 	struct stack_info info;
 
-	if (fp & 0xf)
+	if (fp & 0x7)
 		return -EINVAL;
 
 	if (!tsk)
-- 
2.29.2.454.gaff20da3a2-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-12-03  5:14 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03  5:12 [PATCH v3 1/3] arm64: Change the on_*stack functions to take a size argument Peter Collingbourne
2020-12-03  5:12 ` Peter Collingbourne [this message]
2020-12-03  5:12 ` [PATCH v3 3/3] kasan: arm64: support specialized outlined tag mismatch checks Peter Collingbourne
2020-12-08 17:49   ` Catalin Marinas
2021-01-20 12:41     ` Will Deacon
2021-05-13  2:30       ` Peter Collingbourne
2021-01-07 15:20   ` Andrey Konovalov
2020-12-08 10:20 ` [PATCH v3 1/3] arm64: Change the on_*stack functions to take a size argument Mark Rutland

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=41a146c68cdd682dfee51ef881114dd5c809f2ec.1606972188.git.pcc@google.com \
    --to=pcc@google.com \
    --cc=andreyknvl@google.com \
    --cc=ardb@kernel.org \
    --cc=broonie@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=eugenis@google.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=mark.rutland@arm.com \
    --cc=will@kernel.org \
    /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).