From 9265bc6bce6919c771970e5a425a66551a1c78a0 Mon Sep 17 00:00:00 2001 From: Bjorn Andersson Date: Wed, 20 Sep 2023 19:37:31 -0700 Subject: [PATCH] soc: qcom: rmtfs: Support discarding guard pages In some configurations, the exact placement of the rmtfs shared memory region isn't so strict. The DeviceTree author can then choose to use the "size" property and rely on the OS for placement (in combination with "alloc-ranges", if desired). But on some platforms the rmtfs memory region may not be allocated adjacent to regions allocated by other clients. Add support for discarding the first and last 4k block in the region, if qcom,use-guard-pages is specified in DeviceTree. Signed-off-by: Bjorn Andersson Reviewed-by: Stephan Gerhold Link: https://lore.kernel.org/r/20230920-rmtfs-mem-guard-pages-v3-2-305b37219b78@quicinc.com Signed-off-by: Bjorn Andersson --- drivers/soc/qcom/rmtfs_mem.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/soc/qcom/rmtfs_mem.c b/drivers/soc/qcom/rmtfs_mem.c index f83811f51175..9c937d24ba42 100644 --- a/drivers/soc/qcom/rmtfs_mem.c +++ b/drivers/soc/qcom/rmtfs_mem.c @@ -200,6 +200,15 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev) rmtfs_mem->client_id = client_id; rmtfs_mem->size = rmem->size; + /* + * If requested, discard the first and last 4k block in order to ensure + * that the rmtfs region isn't adjacent to other protected regions. + */ + if (of_property_read_bool(node, "qcom,use-guard-pages")) { + rmtfs_mem->addr += SZ_4K; + rmtfs_mem->size -= 2 * SZ_4K; + } + device_initialize(&rmtfs_mem->dev); rmtfs_mem->dev.parent = &pdev->dev; rmtfs_mem->dev.groups = qcom_rmtfs_mem_groups;