From: Nicolas Pitre Date: Tue, 27 Jan 2015 15:10:42 +0000 (+0100) Subject: ARM: 8294/1: ATAG_DTB_COMPAT: remove the DT workspace's hardcoded 64KB size X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c2607f74aad96d18316a6e709b40e0ffe9def148;p=linux-beck.git ARM: 8294/1: ATAG_DTB_COMPAT: remove the DT workspace's hardcoded 64KB size 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 Tested-by: Pavel Machek Signed-off-by: Nicolas Pitre Signed-off-by: Russell King --- diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 68be9017593d..132c70e2d2f1 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -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 */