Re: [PATCH 3/5] arm64: dts: qcom: ipq5332: add the IMEM node

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] dts: mmio-sram maps inaccessible memory into genalloc pool
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commit 9c529a16f97d21ecf65fd333c3ade51834ef2084
Author: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>

arm64: dts: qcom: ipq5332: add the IMEM node

This commit adds the IMEM node to the ipq5332 device tree to extract debugging
information. It defines an 80KB IMEM region, noting that only the initial 4KB
is accessible by all masters in the SoC.

> diff --git a/arch/arm64/boot/dts/qcom/ipq5332.dtsi b/arch/arm64/boot/dts/qcom/ipq5332.dtsi
> --- a/arch/arm64/boot/dts/qcom/ipq5332.dtsi
> +++ b/arch/arm64/boot/dts/qcom/ipq5332.dtsi
> @@ -493,6 +493,13 @@ qpic_nand: spi@79b0000 {
>  			status = "disabled";
>  		};
>  
> +		sram@8600000 {
> +			compatible = "qcom,ipq5332-imem", "mmio-sram";
> +			reg = <0x08600000 0x14000>;

[Severity: High]
Will this map the inaccessible 76KB of memory into the generic allocator pool?

The commit message notes that only the initial 4KB is accessible, but the
defined region is 80KB (0x14000). Because this node uses the mmio-sram
compatible, the generic sram driver will unconditionally ioremap the full
region and add all unreserved memory into the kernel's genalloc pool:

drivers/misc/sram.c:sram_reserve_regions()
    ret = gen_pool_add_virt(sram->pool,
            (unsigned long)sram->virt_base + cur_start,
            res->start + cur_start, cur_size, -1);

If a driver dynamically requests SRAM, or if speculative hardware accesses
occur across the mapped device memory, could this trigger a fatal synchronous
external abort (SError) and system panic?

Would it be better to either restrict the reg property size to the accessible
4KB (0x1000) or add a driver quirk to explicitly avoid mapping the inaccessible
regions?

> +
> +			no-memory-wc;
> +		};
> +

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Sashiko AI review · https://sashiko.dev/#/patchset/20261001-imem_restart_reason-v1-0-79f516906010@oss.qualcomm.com?part=3