Re: [U-Boot] [PATCH 4/4] arm: factorize relocate_code routine
Hi Benoît, On Sat, 11 May 2013 04:04:09 +0200 (CEST), Benoît Thébaudeau benoit.thebaud...@advansee.com wrote: Hi Albert, On Friday, May 10, 2013 11:56:52 PM, Albert ARIBAUD wrote: Signed-off-by: Albert ARIBAUD albert.u.b...@aribaud.net diff --git a/arch/arm/cpu/pxa/start.S b/arch/arm/cpu/pxa/start.S index ada91a6..3078bec 100644 --- a/arch/arm/cpu/pxa/start.S +++ b/arch/arm/cpu/pxa/start.S @@ -170,90 +170,6 @@ reset: bl _main -/*--*/ -#ifndef CONFIG_SPL_BUILD -/* - * void relocate_code(addr_moni) - * - * This function relocates the monitor code. - */ - .globl relocate_code -relocate_code: - mov r6, r0 /* save addr of destination */ - -/* Disable the Dcache RAM lock for stack now */ -#ifdef CONFIG_CPU_PXA25X - mov r12, lr - bl cpu_init_crit - mov lr, r12 -#endif What about this thing that you silently drop? Overlook on my side, and PXA is not one of my test vehicles so I missed it while testing. Will 'undrop' in V2. diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S new file mode 100644 index 000..ce533ca --- /dev/null +++ b/arch/arm/lib/relocate.S @@ -0,0 +1,100 @@ +/* + * relocate - common relocation function for ARM U-Boot + * + * Copyright (c) 2013 Albert ARIBAUD albert.u.b...@aribaud.net + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +/* + * These are defined in the board-specific linker script. + * Subtracting _start from them lets the linker put their + * relative position in the executable instead of leaving + * them null. + */ + + .globl __image_copy_start + .globl __image_copy_end + .globl __rel_dyn_start + .globl __rel_dyn_end + .globl __dynsym_start .globl is for exporting symbols to the linker, not importing, so the lines above should be removed. correct. Will drop in V2. + +/*--*/ + +/* + * void relocate_code(addr_moni) + * + * This function relocates the monitor code. + */ + .globl relocate_code +relocate_code: Or ENTRY(relocate_code) instead of the two lines above. I'd gone for just moving code around rather than cosmetic, but I can do the cosmetic change at the end of the patch too. + mov r6, r0 /* save addr of destination */ + + ldr r0, =_start This is wrong. Here, r0 will get _start link-time address, while with 'adr' in the original code, r0 was getting _start runtime address, which is not the same for all boards. relocate_code() is and must stay position-independent code, at least for SPL. E.g., for mx31pdk or tx25, the SPL is first loaded by the boot ROM in the NAND Flash controller buffer, then executed from there. The SPL then has to use relocate_code() to relocate itself to CONFIG_SPL_TEXT_BASE in order to free the NFC buffer to load U-Boot from NAND Flash. This means that 'ldr r0, =_start' would set r0 to CONFIG_SPL_TEXT_BASE, while 'adr r0, _start' sets r0 to the address of the NFC buffer. Since the SPL calls relocate_code() with CONFIG_SPL_TEXT_BASE, the 'ldr' choice would just result in a branch to relocate_done below, which would abort the relocation and break the boot on those boards. The issue is that 'adr' requires that _start be defined in the same file and section. That's why my patch 31/31 was using a macro to define relocate_code() in the start.S files. Perhaps some other constructs like 'sub r0, pc, . - _start' would work, but I doubt it if _start is not in the same file and section since this is exactly how 'adr' is translated. Alright, so -- formally, there is no assumption that code running before relocation must be position-independent, as far as I remember. The assumption is that it is designed to run at the link-time location, and that it is responsible for making sure that the rest of the code is properly relocated and thus will run at whatever location it was moved to. In the case you mention, SPL does not relocate itself: it only *moves*
Re: [U-Boot] [PATCH 4/4] arm: factorize relocate_code routine
Hi Albert,
On Saturday, May 11, 2013 9:40:02 AM, Albert ARIBAUD wrote:
Hi Benoît,
On Sat, 11 May 2013 04:04:09 +0200 (CEST), Benoît Thébaudeau
benoit.thebaud...@advansee.com wrote:
Hi Albert,
On Friday, May 10, 2013 11:56:52 PM, Albert ARIBAUD wrote:
Signed-off-by: Albert ARIBAUD albert.u.b...@aribaud.net
[...]
+ mov r6, r0 /* save addr of destination */
+
+ ldr r0, =_start
This is wrong. Here, r0 will get _start link-time address, while with 'adr'
in
the original code, r0 was getting _start runtime address, which is not the
same
for all boards. relocate_code() is and must stay position-independent code,
at
least for SPL.
E.g., for mx31pdk or tx25, the SPL is first loaded by the boot ROM
in the NAND
Flash controller buffer, then executed from there. The SPL then has to use
relocate_code() to relocate itself to CONFIG_SPL_TEXT_BASE in order to free
the
NFC buffer to load U-Boot from NAND Flash. This means that 'ldr r0,
=_start'
would set r0 to CONFIG_SPL_TEXT_BASE, while 'adr r0, _start' sets r0 to the
address of the NFC buffer. Since the SPL calls relocate_code() with
CONFIG_SPL_TEXT_BASE, the 'ldr' choice would just result in a branch to
relocate_done below, which would abort the relocation and break the boot on
those boards.
The issue is that 'adr' requires that _start be defined in the same file
and
section. That's why my patch 31/31 was using a macro to define
relocate_code()
in the start.S files. Perhaps some other constructs like
'sub r0, pc, . - _start' would work, but I doubt it if _start is not in the
same
file and section since this is exactly how 'adr' is translated.
Alright, so -- formally, there is no assumption that code running before
relocation must be position-independent, as far as I remember. The
assumption is that it is designed to run at the link-time location, and
that it is responsible for making sure that the rest of the code is
properly relocated and thus will run at whatever location it was moved
to.
In the case you mention, SPL does not relocate itself: it only *moves*
itself, skipping the actual relocation (reference fixing part) -- it
could havdoe so with a short ad hoc loop instead of relocate_code, and
thus not impose a specific requirement on relocate_code that was not
initially there. I'd be happier with a preprocessor conditional at the
crt0.S stage to choose between relocate_code and a new, short,
move_code routine depending on whether we are building SPL or not.
That being said, I am fine with trying to make the code before
relocation as position-independent as possible anyway; let me see how
this can be done.
OK, I let you try something. Otherwise, I agree with what you say above. The
original code for the non-SPL part below is not position-independent, so it is
safe to assume that only the beginning of relocate_code() (before
'#ifndef CONFIG_SPL_BUILD') should be position-independent, and only for SPL. It
is also probably true that the initial runtime address of all SPLs is known at
build time, so a new CONFIG_SPL_ could be created for that purpose and used in a
dedicated small SPL copy routine, which would also make the need for SPL move
testable at build time, and solve the 'adr' vs. 'ldr' issue.
+ subsr9, r6, r0 /* r9 - relocation offset */
+ beq relocate_done /* skip relocation */
+ mov r1, r6 /* r1 - scratch for copy_loop */
+ ldr r2, =__image_copy_end
+
+copy_loop:
+ ldmia r0!, {r10-r11} /* copy from source address [r0]*/
+ stmia r1!, {r10-r11} /* copy to target address [r1]*/
+ cmp r0, r2 /* until source end address [r2]*/
+ blo copy_loop
+
+#ifndef CONFIG_SPL_BUILD
+ /*
+ * fix .rel.dyn relocations
+ */
+ ldr r0, =_TEXT_BASE /* r0 - Text base */
The value you load above into r0 then gets overwritten prior to having been
used, so you can drop this line, all the more it is wrong, loading the
address
of _TEXT_BASE instead of its value.
Correct. Will fix in V2.
+ ldr r10, =__dynsym_start/* r10 - sym table ofs */
+ ldr r2, =__rel_dyn_start/* r2 - rel dyn start ofs */
+ ldr r3, =__rel_dyn_end /* r3 - rel dyn end ofs */
'ofs' should be replaced with 'in FLASH' in the comments above.
Contrary to above, this construct works here because this can't be SPL
code.
Actually, this would not work either if used by non-SPL code as SPL code
expects to use it, e.g. by loading U-Boot at another address -- the
issue is in the use scenario, not in the requirements for SPL vs.
U-Boot.
Right, but this new code behaves exactly in the same way as the original code,
so it is safe to assume that there is no such use scenario. This new code just
can't introduce a regression.
+relocate_done:
+
+ bx lr
Re: [U-Boot] [PATCH 4/4] arm: factorize relocate_code routine
On Fri, May 10, 2013 at 3:56 PM, Albert ARIBAUD albert.u.b...@aribaud.net wrote: Signed-off-by: Albert ARIBAUD albert.u.b...@aribaud.net --- arch/arm/cpu/arm1136/start.S | 82 arch/arm/cpu/arm1176/start.S | 75 -- arch/arm/cpu/arm720t/start.S | 82 arch/arm/cpu/arm920t/start.S | 75 -- arch/arm/cpu/arm925t/start.S | 75 -- arch/arm/cpu/arm926ejs/start.S | 82 arch/arm/cpu/arm946es/start.S | 75 -- arch/arm/cpu/arm_intcm/start.S | 75 -- arch/arm/cpu/armv7/start.S | 78 --- arch/arm/cpu/ixp/start.S | 75 -- arch/arm/cpu/pxa/start.S | 84 - arch/arm/cpu/s3c44b0/start.S | 75 -- arch/arm/cpu/sa1100/start.S| 75 -- arch/arm/lib/Makefile |2 +- arch/arm/lib/relocate.S| 100 15 files changed, 101 insertions(+), 1009 deletions(-) create mode 100644 arch/arm/lib/relocate.S I tested this series on snow (Exynos 5250, ARMv7, with SPL) with no apparent regressions. Tested-by: Simon Glass s...@chromium.org Regards, Simon ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
[U-Boot] [PATCH 4/4] arm: factorize relocate_code routine
Signed-off-by: Albert ARIBAUD albert.u.b...@aribaud.net
---
arch/arm/cpu/arm1136/start.S | 82
arch/arm/cpu/arm1176/start.S | 75 --
arch/arm/cpu/arm720t/start.S | 82
arch/arm/cpu/arm920t/start.S | 75 --
arch/arm/cpu/arm925t/start.S | 75 --
arch/arm/cpu/arm926ejs/start.S | 82
arch/arm/cpu/arm946es/start.S | 75 --
arch/arm/cpu/arm_intcm/start.S | 75 --
arch/arm/cpu/armv7/start.S | 78 ---
arch/arm/cpu/ixp/start.S | 75 --
arch/arm/cpu/pxa/start.S | 84 -
arch/arm/cpu/s3c44b0/start.S | 75 --
arch/arm/cpu/sa1100/start.S| 75 --
arch/arm/lib/Makefile |2 +-
arch/arm/lib/relocate.S| 100
15 files changed, 101 insertions(+), 1009 deletions(-)
create mode 100644 arch/arm/lib/relocate.S
diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
index ab8fd56..4b3f828 100644
--- a/arch/arm/cpu/arm1136/start.S
+++ b/arch/arm/cpu/arm1136/start.S
@@ -167,88 +167,6 @@ next:
bl _main
-/*--*/
-
-/*
- * void relocate_code(addr_moni)
- *
- * This function relocates the monitor code.
- */
- .globl relocate_code
-relocate_code:
- mov r6, r0 /* save addr of destination */
-
- adr r0, _start
- subsr9, r6, r0 /* r9 - relocation offset */
- beq relocate_done /* skip relocation */
- mov r1, r6 /* r1 - scratch for copy_loop */
- ldr r3, _image_copy_end_ofs
- add r2, r0, r3 /* r2 - source end address */
-
-copy_loop:
- ldmia r0!, {r10-r11} /* copy from source address [r0]*/
- stmia r1!, {r10-r11} /* copy to target address [r1]*/
- cmp r0, r2 /* until source end address [r2]*/
- blo copy_loop
-
-#ifndef CONFIG_SPL_BUILD
- /*
-* fix .rel.dyn relocations
-*/
- ldr r0, _TEXT_BASE /* r0 - Text base */
- ldr r10, _dynsym_start_ofs /* r10 - sym table ofs */
- add r10, r10, r0/* r10 - sym table in FLASH */
- ldr r2, _rel_dyn_start_ofs /* r2 - rel dyn start ofs */
- add r2, r2, r0 /* r2 - rel dyn start in FLASH */
- ldr r3, _rel_dyn_end_ofs/* r3 - rel dyn end ofs */
- add r3, r3, r0 /* r3 - rel dyn end in FLASH */
-fixloop:
- ldr r0, [r2]/* r0 - location to fix up, IN FLASH!
*/
- add r0, r0, r9 /* r0 - location to fix up in RAM */
- ldr r1, [r2, #4]
- and r7, r1, #0xff
- cmp r7, #23 /* relative fixup? */
- beq fixrel
- cmp r7, #2 /* absolute fixup? */
- beq fixabs
- /* ignore unknown type of fixup */
- b fixnext
-fixabs:
- /* absolute fix: set location to (offset) symbol value */
- mov r1, r1, LSR #4 /* r1 - symbol index in .dynsym */
- add r1, r10, r1 /* r1 - address of symbol in table */
- ldr r1, [r1, #4]/* r1 - symbol value */
- add r1, r1, r9 /* r1 - relocated sym addr */
- b fixnext
-fixrel:
- /* relative fix: increase location by offset */
- ldr r1, [r0]
- add r1, r1, r9
-fixnext:
- str r1, [r0]
- add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
- cmp r2, r3
- blo fixloop
-#endif
-
-relocate_done:
-
- bx lr
-
-_image_copy_end_ofs:
- .word __image_copy_end - _start
-
-#ifndef CONFIG_SPL_BUILD
-
-_rel_dyn_start_ofs:
- .word __rel_dyn_start - _start
-_rel_dyn_end_ofs:
- .word __rel_dyn_end - _start
-_dynsym_start_ofs:
- .word __dynsym_start - _start
-
-#endif
-
.globl c_runtime_cpu_setup
c_runtime_cpu_setup:
diff --git a/arch/arm/cpu/arm1176/start.S b/arch/arm/cpu/arm1176/start.S
index f20da8e..6929b08 100644
--- a/arch/arm/cpu/arm1176/start.S
+++ b/arch/arm/cpu/arm1176/start.S
@@ -223,81 +223,6 @@ skip_tcmdisable:
bl _main
-/*--*/
-
-/*
- * void relocate_code(addr_moni)
- *
- * This function relocates the monitor code.
- */
- .globl relocate_code
-relocate_code:
- mov r6, r0 /* save addr of destination */
-
- adr r0, _start
- subsr9, r6, r0
Re: [U-Boot] [PATCH 4/4] arm: factorize relocate_code routine
Hi Albert,
On Friday, May 10, 2013 11:56:52 PM, Albert ARIBAUD wrote:
Signed-off-by: Albert ARIBAUD albert.u.b...@aribaud.net
---
arch/arm/cpu/arm1136/start.S | 82
arch/arm/cpu/arm1176/start.S | 75 --
arch/arm/cpu/arm720t/start.S | 82
arch/arm/cpu/arm920t/start.S | 75 --
arch/arm/cpu/arm925t/start.S | 75 --
arch/arm/cpu/arm926ejs/start.S | 82
arch/arm/cpu/arm946es/start.S | 75 --
arch/arm/cpu/arm_intcm/start.S | 75 --
arch/arm/cpu/armv7/start.S | 78 ---
arch/arm/cpu/ixp/start.S | 75 --
arch/arm/cpu/pxa/start.S | 84 -
arch/arm/cpu/s3c44b0/start.S | 75 --
arch/arm/cpu/sa1100/start.S| 75 --
arch/arm/lib/Makefile |2 +-
arch/arm/lib/relocate.S| 100
15 files changed, 101 insertions(+), 1009 deletions(-)
create mode 100644 arch/arm/lib/relocate.S
[...]
diff --git a/arch/arm/cpu/pxa/start.S b/arch/arm/cpu/pxa/start.S
index ada91a6..3078bec 100644
--- a/arch/arm/cpu/pxa/start.S
+++ b/arch/arm/cpu/pxa/start.S
@@ -170,90 +170,6 @@ reset:
bl _main
-/*--*/
-#ifndef CONFIG_SPL_BUILD
-/*
- * void relocate_code(addr_moni)
- *
- * This function relocates the monitor code.
- */
- .globl relocate_code
-relocate_code:
- mov r6, r0 /* save addr of destination */
-
-/* Disable the Dcache RAM lock for stack now */
-#ifdef CONFIG_CPU_PXA25X
- mov r12, lr
- bl cpu_init_crit
- mov lr, r12
-#endif
What about this thing that you silently drop?
-
- adr r0, _start
- subsr9, r6, r0 /* r9 - relocation offset */
- beq relocate_done /* skip relocation */
- mov r1, r6 /* r1 - scratch for copy_loop */
- ldr r3, _image_copy_end_ofs
- add r2, r0, r3 /* r2 - source end address */
-
-copy_loop:
- ldmia r0!, {r10-r11} /* copy from source address [r0]*/
- stmia r1!, {r10-r11} /* copy to target address [r1]*/
- cmp r0, r2 /* until source end address [r2]*/
- blo copy_loop
-
-#ifndef CONFIG_SPL_BUILD
- /*
- * fix .rel.dyn relocations
- */
- ldr r0, _TEXT_BASE /* r0 - Text base */
- ldr r10, _dynsym_start_ofs /* r10 - sym table ofs */
- add r10, r10, r0/* r10 - sym table in FLASH */
- ldr r2, _rel_dyn_start_ofs /* r2 - rel dyn start ofs */
- add r2, r2, r0 /* r2 - rel dyn start in FLASH */
- ldr r3, _rel_dyn_end_ofs/* r3 - rel dyn end ofs */
- add r3, r3, r0 /* r3 - rel dyn end in FLASH */
-fixloop:
- ldr r0, [r2]/* r0 - location to fix up, IN FLASH!
*/
- add r0, r0, r9 /* r0 - location to fix up in RAM */
- ldr r1, [r2, #4]
- and r7, r1, #0xff
- cmp r7, #23 /* relative fixup? */
- beq fixrel
- cmp r7, #2 /* absolute fixup? */
- beq fixabs
- /* ignore unknown type of fixup */
- b fixnext
-fixabs:
- /* absolute fix: set location to (offset) symbol value */
- mov r1, r1, LSR #4 /* r1 - symbol index in .dynsym */
- add r1, r10, r1 /* r1 - address of symbol in table */
- ldr r1, [r1, #4]/* r1 - symbol value */
- add r1, r1, r9 /* r1 - relocated sym addr */
- b fixnext
-fixrel:
- /* relative fix: increase location by offset */
- ldr r1, [r0]
- add r1, r1, r9
-fixnext:
- str r1, [r0]
- add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
- cmp r2, r3
- blo fixloop
-#endif
-
-relocate_done:
-
- bx lr
-
-_rel_dyn_start_ofs:
- .word __rel_dyn_start - _start
-_rel_dyn_end_ofs:
- .word __rel_dyn_end - _start
-_dynsym_start_ofs:
- .word __dynsym_start - _start
-
-#endif
-
.globl c_runtime_cpu_setup
c_runtime_cpu_setup:
[...]
diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
new file mode 100644
index 000..ce533ca
--- /dev/null
+++ b/arch/arm/lib/relocate.S
@@ -0,0 +1,100 @@
+/*
+ * relocate - common relocation function for ARM U-Boot
+ *
+ * Copyright (c) 2013 Albert ARIBAUD albert.u.b...@aribaud.net
+ *
+ * See file CREDITS for list of
