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authorOleksij Rempel <o.rempel@pengutronix.de>2020-01-30 08:38:57 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2020-02-03 09:17:53 +0100
commitc622c8be4ee14454bc3590735af8be6ca5e989fe (patch)
tree9f101bd3b5dcce251e2b0de245f2323f264f4709 /arch/mips/lib/reloc.c
parentb7a9e582c393e8fcd1e22044dd7384734d9e5a7a (diff)
downloadbarebox-c622c8be4ee14454bc3590735af8be6ca5e989fe.tar.gz
MIPS: don't overlay relocation data with BSS
.bss __rel_start (OVERLAY) was used to optimize RAM size used by barebox. Since .bss and __rel_start overlap, we should clear bss only after __rel_start was used. Following patch changed initialization sequence to clear .bss before __rel_start: 1e5aef61fc6a444 ("MIPS: reloc: init bss and cpu") This make relocation buffer unusable and broke relocation with different symptoms reported by Antony Pavlov <antonynpavlov@gmail.com>: * iomem output has no information on sdram regions, so memtest is unusable; * pc = 0xa081232c, relocation does not work, barebox is located with 8M offset from start of RAM. The board has 256M and relocation routine should move barebox code much higher; * pc = 0xa081232c, so barebox code works from KSEG1 not from KSEG0 as MMU=y option implies. There is a choice of moving .bss clear sequence after __rel_start or remove this optimization. Since the use of this optimization is minimal and danger to trap in to similar issue is still high, i prefer to remove this optimization. As result of this change, we need to fix calculation of relocation are size: relocate_code() calculates relocation area size as a sum (barebox_image_size + bss_len). barebox_image_size and bss_len are calculated as (__image_end - __image_start) and (__bss_stop - __bss_start) respectively. This doesn't take into account relocation data placed between __image_end and __bss_start. However relocation preserves BSS position relative to image start, as if relocation data is still there. This causes RAM overflow during BSS initialization in main_entry(). This problem may be hidden due to the alignment of the `relocaddr`. Reported-by: Antony Pavlov <antonynpavlov@gmail.com> Fixes: 1e5aef61fc6a444 ("MIPS: reloc: init bss and cpu") Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> Signed-off-by: Peter Mamonov <pmamonov@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/mips/lib/reloc.c')
-rw-r--r--arch/mips/lib/reloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c
index df9760e..4b0e252 100644
--- a/arch/mips/lib/reloc.c
+++ b/arch/mips/lib/reloc.c
@@ -118,7 +118,7 @@ void relocate_code(void *fdt, u32 fdt_size, u32 ram_size)
memset(__bss_start, 0, bss_len);
cpu_probe();
- length = barebox_image_size + bss_len;
+ length = __bss_stop - __image_start;
relocaddr = ALIGN_DOWN(ram_size - length, SZ_64K);
relocaddr = KSEG0ADDR(relocaddr);
new_stack = relocaddr - MALLOC_SIZE - 16;