| Commit message (Collapse) | Author | Age | Files | Lines |
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Improves the code readability a tiny little bit.
Signed-off-by: Denis Orlov <denorl2009@gmail.com>
Link: https://lore.barebox.org/20230725050618.3451-22-denorl2009@gmail.com
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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After relocating the code we jump straight to it, with the function
having an 'unreachable()' call at the end. So add an appropriate
attribute.
Signed-off-by: Denis Orlov <denorl2009@gmail.com>
Link: https://lore.barebox.org/20230725050618.3451-6-denorl2009@gmail.com
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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Use CKSEG instead of KSEG, allowing it to compile on 64BIT
configurations. Also make sure that we do not truncate target
relocation address by writing it into a 32-bit wide variable.
Signed-off-by: Denis Orlov <denorl2009@gmail.com>
Reviewd-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20230605202634.42175-4-denorl2009@gmail.com
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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There are some issues with CONFIG_MMU=n in MIPS configuration
(e.g. qemu-malta_defconfig):
* "Cannot request SDRAM region for stack" error message on start;
* empty kseg1_ram0 region in the iomem command output.
The patch fixes the problems by forcing KSEG1 memory region usage
for CONFIG_MMU=n MIPS configurations.
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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.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>
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We need it to make flush_cache_all() work properly.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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It will be done in main_entry() any way.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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In this relocate_code() piece 'length' is greater than 'barebox_image_size':
#define MAX_BSS_SIZE SZ_1M
...
length = barebox_image_size + MAX_BSS_SIZE;
relocaddr = ALIGN_DOWN(ram_size - barebox_image_size, SZ_64K);
...
memcpy((void *)relocaddr, __image_start, length);
so 'ram_size' overflow occurs during memcpy().
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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this patch i a port of following patch from u-boot with some additional
integration changes and fixes of original code:
| Subject: [PATCH] MIPS: Stop building position independent code
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| U-Boot has up until now built with -fpic for the MIPS architecture,
| producing position independent code which uses indirection through a
| global offset table, making relocation fairly straightforward as it
| simply involves patching up GOT entries.
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| Using -fpic does however have some downsides. The biggest of these is
| that generated code is bloated in various ways. For example, function
| calls are indirected through the GOT & the t9 register:
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| 8f998064 lw t9,-32668(gp)
| 0320f809 jalr t9
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| Without -fpic the call is simply:
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| 0f803f01 jal be00fc04 <puts>
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| This is more compact & faster (due to the lack of the load & the
| dependency the jump has on its result). It is also easier to read &
| debug because the disassembly shows what function is being called,
| rather than just an offset from gp which would then have to be looked up
| in the ELF to discover the target function.
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| Another disadvantage of -fpic is that each function begins with a
| sequence to calculate the value of the gp register, for example:
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| 3c1c0004 lui gp,0x4
| 279c3384 addiu gp,gp,13188
| 0399e021 addu gp,gp,t9
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| Without using -fpic this sequence no longer appears at the start of each
| function, reducing code size considerably.
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| This patch switches U-Boot from building with -fpic to building with
| -fno-pic, in order to gain the benefits described above. The cost of
| this is an extra step during the build process to extract relocation
| data from the ELF & write it into a new .rel section in a compact
| format, plus the added complexity of dealing with multiple types of
| relocation rather than the single type that applied to the GOT. The
| benefit is smaller, cleaner, more debuggable code. The relocate_code()
| function is reimplemented in C to handle the new relocation scheme,
| which also makes it easier to read & debug.
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| Taking maltael_defconfig as an example the size of u-boot.bin built
| using the Codescape MIPS 2016.05-06 toolchain (gcc 4.9.2, binutils
| 2.24.90) shrinks from 254KiB to 224KiB.
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| Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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