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