From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: barebox@lists.infradead.org
Cc: lst@pengutronix.de, Ahmad Fatoum <a.fatoum@pengutronix.de>
Subject: [PATCH 4/4] dma: debug: detect repeated DMA sync using KASAN
Date: Tue, 10 Sep 2024 13:48:32 +0200 [thread overview]
Message-ID: <20240910114832.2984195-5-a.fatoum@pengutronix.de> (raw)
In-Reply-To: <20240910114832.2984195-1-a.fatoum@pengutronix.de>
Now that we poison/unpoison DMA buffers as part of ownership transfer,
it's possible for us to detect repeated sync's that are unnecessary at a
granularity of cache lines, which was not possible with the initial
approach in commit 1ad4b32702dd ("dma: debug: detect repeated DMA
sync").
Such repeated sync's are usually a result of mapping a buffer and then
calling dma_sync_single_for_device on it. This is unnecessary and warrants
a renewed look at the DMA management scheme, which this warning hopefully
accomplishes.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
drivers/dma/debug.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/debug.c b/drivers/dma/debug.c
index fd279be5be02..01a3832ea30a 100644
--- a/drivers/dma/debug.c
+++ b/drivers/dma/debug.c
@@ -213,7 +213,14 @@ void debug_dma_sync_single_for_cpu(struct device *dev,
cpu_addr = dma_debug_entry_cpu_addr(entry, dma_handle);
if (cpu_addr) {
- kasan_unpoison_shadow(cpu_addr, DMA_KASAN_ALIGN(size));
+ size_t kasan_size = DMA_KASAN_ALIGN(size);
+
+ if (kasan_is_poisoned_shadow(cpu_addr, kasan_size) == 0) {
+ dma_dev_warn(dev, "unexpected sync for CPU of already CPU-mapped %s buffer 0x%llx+0x%zx!\n",
+ dir2name[direction], (u64)dma_handle, size);
+ } else {
+ kasan_unpoison_shadow(cpu_addr, kasan_size);
+ }
}
}
@@ -239,6 +246,15 @@ void debug_dma_sync_single_for_device(struct device *dev,
cpu_addr = dma_debug_entry_cpu_addr(entry, dma_handle);
if (cpu_addr) {
- kasan_poison_shadow(cpu_addr, DMA_KASAN_ALIGN(size), KASAN_DMA_DEV_MAPPED);
+ size_t kasan_size = DMA_KASAN_ALIGN(size);
+
+ /* explicit == 1 check as function may return negative value on error */
+ if (kasan_is_poisoned_shadow(cpu_addr, kasan_size) == 1) {
+ dma_dev_warn(dev, "unexpected sync for device of already device-mapped %s buffer 0x%llx+0x%zx!\n",
+ dir2name[direction], (u64)dma_handle, size);
+ } else {
+ kasan_poison_shadow(cpu_addr, kasan_size, KASAN_DMA_DEV_MAPPED);
+ }
+
}
}
--
2.39.2
prev parent reply other threads:[~2024-09-10 11:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-10 11:48 [PATCH 0/4] dma: debug: track DMA buffer ownership with KASAN Ahmad Fatoum
2024-09-10 11:48 ` [PATCH 1/4] Revert "dma: debug: detect repeated DMA sync" Ahmad Fatoum
2024-09-10 11:48 ` [PATCH 2/4] KASan: implement non-warning kasan_is_poisoned_shadow Ahmad Fatoum
2024-09-10 11:48 ` [PATCH 3/4] dma: debug: poison DMA buffers with KASAN while owned by device Ahmad Fatoum
2024-09-10 11:48 ` Ahmad Fatoum [this message]
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=20240910114832.2984195-5-a.fatoum@pengutronix.de \
--to=a.fatoum@pengutronix.de \
--cc=barebox@lists.infradead.org \
--cc=lst@pengutronix.de \
/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