From c159a0ec4a41a4243df60a1a94c1d4848f6492c5 Mon Sep 17 00:00:00 2001 From: Jimmy Huang Date: Tue, 15 Sep 2015 15:29:10 +0800 Subject: arm64: mmu: Prevent CPU prefetch instructions from device memory Set XN bit of block upper attribute to device memory in mmu. CPU may speculatively prefetch instructions from device memory, but the IO subsystem of some implementation may not support this operation. Set this attribute to device memory mmu entries can prevent CPU from prefetching device memory. BRANCH=none BUG=none TEST=build and booted to kernel on oak-rev3 with dcm enabled. Change-Id: I52ac7d7c84220624aaf6a48d64b9110d7afeb293 Signed-off-by: Patrick Georgi Original-Commit-Id: 7b01a4157cb046a5e75ea7625060a602e7a63c3c Original-Change-Id: Id535e990a23b6c89123b5a4e64d7ed21eebed607 Original-Signed-off-by: Jimmy Huang Original-Reviewed-on: https://chromium-review.googlesource.com/302301 Original-Commit-Ready: Yidi Lin Original-Tested-by: Yidi Lin Original-Reviewed-by: Aaron Durbin Original-Reviewed-by: Julius Werner Reviewed-on: http://review.coreboot.org/11722 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi --- payloads/libpayload/arch/arm64/mmu.c | 1 + 1 file changed, 1 insertion(+) (limited to 'payloads/libpayload/arch') diff --git a/payloads/libpayload/arch/arm64/mmu.c b/payloads/libpayload/arch/arm64/mmu.c index e2a0cb18b6..f07e4c435c 100644 --- a/payloads/libpayload/arch/arm64/mmu.c +++ b/payloads/libpayload/arch/arm64/mmu.c @@ -91,6 +91,7 @@ static uint64_t get_block_attr(unsigned long tag) break; case TYPE_DEV_MEM: attr |= BLOCK_INDEX_MEM_DEV_NGNRNE << BLOCK_INDEX_SHIFT; + attr |= BLOCK_XN; break; case TYPE_DMA_MEM: attr |= BLOCK_INDEX_MEM_NORMAL_NC << BLOCK_INDEX_SHIFT; -- cgit v1.2.3