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ARM: 8294/1: ATAG_DTB_COMPAT: remove the DT workspace's hardcoded 64KB size

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There is currently a hardcoded limit of 64KB for the DTB to live in and
be extended with ATAG info.  Some DTBs have outgrown that limit:

$ du -b arch/arm/boot/dts/omap3-n900.dtb
70212   arch/arm/boot/dts/omap3-n900.dtb

Furthermore, the actual size passed to atags_to_fdt() included the stack
size which is obviously wrong.

The initial DTB size is known, so use it to size the allocated workspace
with a 50% growth assumption and relocate the temporary stack above that.
This is also clamped to 32KB min / 1MB max for robustness against bad
DTB data.

Reported-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Nicolas Pitre 2015-01-27 16:10:42 +01:00 committed by Russell King
parent c2273a1853
commit c2607f74aa
1 changed files with 30 additions and 9 deletions
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39
arch/arm/boot/compressed/head.S
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@ -263,16 +263,37 @@ restart: adr r0, LC0
* OK... Let's do some funky business here.
* If we do have a DTB appended to zImage, and we do have
* an ATAG list around, we want the later to be translated
* and folded into the former here. To be on the safe side,
* let's temporarily move the stack away into the malloc
* area. No GOT fixup has occurred yet, but none of the
* code we're about to call uses any global variable.
* and folded into the former here. No GOT fixup has occurred
* yet, but none of the code we're about to call uses any
* global variable.
*/
add sp, sp, #0x10000
/* Get the initial DTB size */
ldr r5, [r6, #4]
#ifndef __ARMEB__
/* convert to little endian */
eor r1, r5, r5, ror #16
bic r1, r1, #0x00ff0000
mov r5, r5, ror #8
eor r5, r5, r1, lsr #8
#endif
/* 50% DTB growth should be good enough */
add r5, r5, r5, lsr #1
/* preserve 64-bit alignment */
add r5, r5, #7
bic r5, r5, #7
/* clamp to 32KB min and 1MB max */
cmp r5, #(1 << 15)
movlo r5, #(1 << 15)
cmp r5, #(1 << 20)
movhi r5, #(1 << 20)
/* temporarily relocate the stack past the DTB work space */
add sp, sp, r5
stmfd sp!, {r0-r3, ip, lr}
mov r0, r8
mov r1, r6
sub r2, sp, r6
mov r2, r5
bl atags_to_fdt
/*
@ -285,11 +306,11 @@ restart: adr r0, LC0
bic r0, r0, #1
add r0, r0, #0x100
mov r1, r6
sub r2, sp, r6
mov r2, r5
bleq atags_to_fdt
ldmfd sp!, {r0-r3, ip, lr}
sub sp, sp, #0x10000
sub sp, sp, r5
#endif
mov r8, r6 @ use the appended device tree
@ -306,7 +327,7 @@ restart: adr r0, LC0
subs r1, r5, r1
addhi r9, r9, r1
/* Get the dtb's size */
/* Get the current DTB size */
ldr r5, [r6, #4]
#ifndef __ARMEB__
/* convert r5 (dtb size) to little endian */