From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ix4Pq-0005Xx-Rb for barebox@lists.infradead.org; Thu, 30 Jan 2020 07:39:08 +0000 From: Oleksij Rempel Date: Thu, 30 Jan 2020 08:38:57 +0100 Message-Id: <20200130073857.18396-1-o.rempel@pengutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH v4] MIPS: don't overlay relocation data with BSS To: antonynpavlov@gmail.com, barebox@lists.infradead.org Cc: Oleksij Rempel , Peter Mamonov .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 : * 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 Fixes: 1e5aef61fc6a444 ("MIPS: reloc: init bss and cpu") Signed-off-by: Oleksij Rempel Signed-off-by: Peter Mamonov --- arch/mips/lib/barebox.lds.S | 2 +- arch/mips/lib/reloc.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/mips/lib/barebox.lds.S b/arch/mips/lib/barebox.lds.S index 693a778980..c954df41f3 100644 --- a/arch/mips/lib/barebox.lds.S +++ b/arch/mips/lib/barebox.lds.S @@ -59,7 +59,7 @@ SECTIONS _end = .; - .bss __rel_start (OVERLAY) : { + .bss : { __bss_start = .; *(.sbss.*) *(.bss.*) diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c index df9760e38c..4b0e252352 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; -- 2.25.0 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox