N900 v3.19-rc5 arm atags_to_fdt.c is broken
From: Pavel Machek <hidden>
Date: 2015-01-27 13:37:45
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linux-omap, lkml
quoted
quoted
I would say, problem is because omap3-n900 binary DT is too largeI agree.quoted
OK if that's the case, then your patch makes sense to me. It also seems we can have the temporary stack be larger than the initial stack just for atags_to_fdt.The stack size isn't the issue, but rather its location. We need to position it away from the DT data. The DT size is known and we could use that, plus some room for the insertion of new data coming from the ATAG conversion. Something like the following would be a more robust solution:
Tested-by: Pavel Machek <redacted> (Note, that in 3.19 dts for n900 got too big, so we are actually triggering old bugs. That means that this is a regression fix, and should go in ASAP).
quoted hunk ↗ jump to hunk
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 68be901759..89718de9dd 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 */ + movs r1, r5, lsr #15 + moveq r5, #(1 << 15) + movs r1, r5, lsr #20 + movne 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 */
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