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Commit 15ea6a8a authored by Prasad Sodagudi's avatar Prasad Sodagudi Committed by Matt Wagantall
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ARM: decompressor: avoid speculative prefetch from protected regions 



Currently first 1GB memory mapped with read, write and execute
permissions and unfortunately speculative prefetch causing
undesirable sideffects if those regions are protected.

Hence the flag CONFIG_ARM_DECOMPRESSOR_LIMIT limit the size
of the memory to be mapped by decompressor with read, write
and execute permissions to avoid speculative prefetch.

Change-Id: I3f2495649153ae16040579b71dff5b78315b29a8
Signed-off-by: default avatarPrasad Sodagudi <psodagud@codeaurora.org>
parent a546ed61

arch/arm/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -2078,6 +2078,17 @@ config AUTO_ZRELADDR 
	  0xf8000000. This assumes the zImage being placed in the first 128MB

	  from start of memory.



config ARM_DECOMPRESSOR_LIMIT

	hex "Limit the decompressor memory area"

	default 0x10000000

	help

	  Allows overriding of the memory size that decompressor maps with

	  read, write and execute permissions to avoid speculative prefetch.



	  By default ARM_DECOMPRESSOR_LIMIT maps first 1GB of memory

	  with read, write and execute permissions and reset of the memory

	  as strongly ordered.



endmenu



menu "CPU Power Management"

arch/arm/boot/compressed/head.S

+1 −1
Original line number Diff line number Diff line
@@ -639,7 +639,7 @@ __setup_mmu: sub r3, r4, #16384 @ Page directory size 
		mov	r0, r3

		mov	r9, r0, lsr #18

		mov	r9, r9, lsl #18		@ start of RAM

		add	r10, r9, #0x10000000	@ a reasonable RAM size

		add	r10, r9, #CONFIG_ARM_DECOMPRESSOR_LIMIT

		mov	r1, #0x12		@ XN|U + section mapping

		orr	r1, r1, #3 << 10	@ AP=11

		add	r2, r3, #16384