| From f96fd2f72a33dbb5b688afb176a3a0ae0002ce01 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sun, 2 May 2021 01:42:57 +0000 |
| Subject: arm64: dts: qcom: sdm845-oneplus-common: guard rmtfs-mem |
| |
| From: Caleb Connolly <caleb@connolly.tech> |
| |
| [ Upstream commit e60fd5ac1f6851be5b2c042b39584bfcf8a66f57 ] |
| |
| 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. |
| |
| Fixes: 288ef8a42612 ("arm64: dts: sdm845: add oneplus6/6t devices") |
| Signed-off-by: Caleb Connolly <caleb@connolly.tech> |
| Link: https://lore.kernel.org/r/20210502014146.85642-4-caleb@connolly.tech |
| Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| 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 8f617f7b6d34..f712771df0c7 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 @@ |
| }; |
| |
| 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 @@ |
| 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 |
| |
