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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 <pgeorgi@chromium.org>
Original-Commit-Id: 7b01a4157cb046a5e75ea7625060a602e7a63c3c
Original-Change-Id: Id535e990a23b6c89123b5a4e64d7ed21eebed607
Original-Signed-off-by: Jimmy Huang <jimmy.huang@mediatek.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/302301
Original-Commit-Ready: Yidi Lin <yidi.lin@mediatek.com>
Original-Tested-by: Yidi Lin <yidi.lin@mediatek.com>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: http://review.coreboot.org/11722
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
This commit is contained in:
Jimmy Huang 2015-09-15 15:29:10 +08:00 committed by Patrick Georgi
parent bf7b5bc64a
commit c159a0ec4a
4 changed files with 6 additions and 0 deletions
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1
payloads/libpayload/arch/arm64/mmu.c
View File

@ -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;

2
payloads/libpayload/include/arm64/arch/mmu.h
View File

@ -72,6 +72,8 @@ extern char _start[], _end[];
#define BLOCK_ACCESS (1 << 10)
#define BLOCK_XN (1UL << 54)
#define BLOCK_SH_SHIFT (8)
#define BLOCK_SH_NON_SHAREABLE (0 << BLOCK_SH_SHIFT)
#define BLOCK_SH_UNPREDICTABLE (1 << BLOCK_SH_SHIFT)

1
src/arch/arm64/armv8/mmu.c
View File

@ -76,6 +76,7 @@ static uint64_t get_block_attr(unsigned long tag)
attr |= BLOCK_INDEX_MEM_NORMAL << BLOCK_INDEX_SHIFT;
} else {
attr |= BLOCK_INDEX_MEM_DEV_NGNRNE << BLOCK_INDEX_SHIFT;
attr |= BLOCK_XN;
}
return attr;

2
src/arch/arm64/include/armv8/arch/mmu.h
View File

@ -56,6 +56,8 @@
#define BLOCK_ACCESS (1 << 10)
#define BLOCK_XN (1UL << 54)
#define BLOCK_SH_SHIFT (8)
#define BLOCK_SH_NON_SHAREABLE (0 << BLOCK_SH_SHIFT)
#define BLOCK_SH_UNPREDICTABLE (1 << BLOCK_SH_SHIFT)