Linux-ARM-MSM Archive on lore.kernel.org
 help / color / Atom feed
From: Caleb Connolly <caleb@connolly.tech>
To: caleb@connolly.tech, Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Rob Herring <robh+dt@kernel.org>
Cc: ~postmarketos/upstreaming@lists.sr.ht,
	phone-devel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 3/4] dts: qcom: sdm845-oneplus-common: guard rmtfs-mem
Date: Sun, 02 May 2021 01:42:57 +0000
Message-ID: <20210502014146.85642-4-caleb@connolly.tech> (raw)

The rmtfs_mem region is a weird one, downstream allocates it
dynamically, and supports a "qcom,guard-memory" property which when set
will reserve 4k above and below the rmtfs memory.

A common from qcom 4.9 kernel msm_sharedmem driver:

/*
 * If guard_memory is set, then the shared memory region
 * will be guarded by SZ_4K at the start and at the end.
 * This is needed to overcome the XPU limitation on few
 * MSM HW, so as to make this memory not contiguous with
 * other allocations that may possibly happen from other
 * clients in the system.
*/

When the kernel tries to touch memory that is too close the
rmtfs region it may cause an XPU violation. Such is the case on the
OnePlus 6 where random crashes would occur usually after boot.

Reserve 4k above and below the rmtfs_mem to avoid hitting these XPU
Violations.

This doesn't entirely solve the random crashes on the OnePlus 6/6T but
it does seem to prevent the ones which happen shortly after modem
bringup.

Signed-off-by: Caleb Connolly <caleb@connolly.tech>
---
 arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
index 8f3f5c687b4a..96c370b90550 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
+++ b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
@@ -46,6 +46,14 @@ vol-up {
 	};
 
 	reserved-memory {
+		/* The rmtfs_mem needs to be guarded due to "XPU limitations"
+		 * it is otherwise possible for an allocation adjacent to the
+		 * rmtfs_mem region to trigger an XPU violation, causing a crash.
+		 */
+		rmtfs_lower_guard: memory@f5b00000 {
+			no-map;
+			reg = <0 0xf5b00000 0 0x1000>;
+		};
 		/*
 		 * The rmtfs memory region in downstream is 'dynamically allocated'
 		 * but given the same address every time. Hard code it as this address is
@@ -59,6 +67,10 @@ rmtfs_mem: memory@f5b01000 {
 			qcom,client-id = <1>;
 			qcom,vmid = <15>;
 		};
+		rmtfs_upper_guard: memory@f5d01000 {
+			no-map;
+			reg = <0 0xf5d01000 0 0x2000>;
+		};
 
 		/*
 		 * It seems like reserving the old rmtfs_mem region is also needed to prevent
-- 
2.30.2



                 reply index

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=20210502014146.85642-4-caleb@connolly.tech \
    --to=caleb@connolly.tech \
    --cc=agross@kernel.org \
    --cc=bjorn.andersson@linaro.org \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=phone-devel@vger.kernel.org \
    --cc=robh+dt@kernel.org \
    --cc=~postmarketos/upstreaming@lists.sr.ht \
    /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

Linux-ARM-MSM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-msm/0 linux-arm-msm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-msm linux-arm-msm/ https://lore.kernel.org/linux-arm-msm \
		linux-arm-msm@vger.kernel.org
	public-inbox-index linux-arm-msm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-arm-msm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git