Commit f9a36bda authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Felix Fu
Browse files

ARM: decompressor: explicitly map decompressor binary cacheable 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8KNA9
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?h=arm-kaslr-latest&id=a58cdcfbee11974669a651e3ce049ef729e81411



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When randomizing the kernel load address, there may be a large
distance in memory between the decompressor binary and its payload
and the destination area in memory. Ensure that the decompressor
itself is mapped cacheable in this case, by tweaking the existing
routine that takes care of this for XIP decompressors.

Cc: Russell King <linux@armlinux.org.uk>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarFelix Fu <fuzhen5@huawei.com>
parent 08c92891

arch/arm/boot/compressed/head.S

+10 −6
Original line number Diff line number Diff line
@@ -814,20 +814,24 @@ __setup_mmu: sub r3, r4, #16384 @ Page directory size 
		teq	r0, r2

		bne	1b

/*

 * If ever we are running from Flash, then we surely want the cache

 * to be enabled also for our execution instance...  We map 2MB of it

 * so there is no map overlap problem for up to 1 MB compressed kernel.

 * If the execution is in RAM then we would only be duplicating the above.

 * Make sure our entire executable image (including payload) is mapped

 * cacheable, in case it is located outside the region we covered above.

 * (This may be the case if running from flash or with randomization enabled)

 * If the regions happen to overlap, we just duplicate some of the above.

 */

		orr	r1, r6, #0x04		@ ensure B is set for this

		orr	r1, r1, #3 << 10

		mov	r2, pc

		adr_l	r9, _end

		mov	r2, r2, lsr #20

		mov	r9, r9, lsr #20

		orr	r1, r1, r2, lsl #20

		add	r0, r3, r2, lsl #2

		str	r1, [r0], #4

		add	r9, r3, r9, lsl #2

0:		str	r1, [r0], #4

		add	r1, r1, #1048576

		str	r1, [r0]

		cmp	r0, r9

		bls	0b

		mov	pc, lr

ENDPROC(__setup_mmu)