* [PATCH] MIPS: Allow compressed images to be loaded at the usual address
@ 2017-02-05 20:21 Alban
2017-02-06 8:52 ` Sergei Shtylyov
2017-02-09 12:22 ` Jonas Gorski
0 siblings, 2 replies; 5+ messages in thread
From: Alban @ 2017-02-05 20:21 UTC (permalink / raw)
To: linux-mips; +Cc: Alban Bedel, Ralf Baechle, Jonas Gorski, linux-kernel
From: Alban Bedel <albeu@free.fr>
Normally compressed images have to be loaded at a different address to
allow the decompressor to run. This add an option to let vmlinuz copy
itself to the correct address from the normal vmlinux address.
Signed-off-by: Alban Bedel <albeu@free.fr>
---
arch/mips/Kconfig | 8 ++++++++
arch/mips/boot/compressed/head.S | 13 +++++++++++++
2 files changed, 21 insertions(+)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b3c5bde..8074fc5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2961,6 +2961,14 @@ choice
bool "Extend builtin kernel arguments with bootloader arguments"
endchoice
+config ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
+ bool "Load compressed images at the same address as uncompressed"
+ depends on SYS_SUPPORTS_ZBOOT
+ help
+ vmlinux and vmlinuz normally have different load addresses, with
+ this option vmlinuz expect to be loaded at the same address as
+ vmlinux.
+
endmenu
config LOCKDEP_SUPPORT
diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
index 409cb48..a215171 100644
--- a/arch/mips/boot/compressed/head.S
+++ b/arch/mips/boot/compressed/head.S
@@ -25,6 +25,19 @@ start:
move s2, a2
move s3, a3
+#ifdef CONFIG_ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
+ /* Move the text, data section and DTB to the correct address */
+ PTR_LA a0, .text
+ PTR_LI a1, VMLINUX_LOAD_ADDRESS
+ PTR_LA a2, _edata
+0:
+ lw a3, 0(a1)
+ sw a3, 0(a0)
+ addiu a1, a1, 4
+ bne a2, a0, 0b
+ addiu a0, a0, 4
+#endif
+
/* Clear BSS */
PTR_LA a0, _edata
PTR_LA a2, _end
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] MIPS: Allow compressed images to be loaded at the usual address
2017-02-05 20:21 [PATCH] MIPS: Allow compressed images to be loaded at the usual address Alban
@ 2017-02-06 8:52 ` Sergei Shtylyov
2017-02-09 12:22 ` Jonas Gorski
1 sibling, 0 replies; 5+ messages in thread
From: Sergei Shtylyov @ 2017-02-06 8:52 UTC (permalink / raw)
To: Alban, linux-mips; +Cc: Ralf Baechle, Jonas Gorski, linux-kernel
Hello!
On 2/5/2017 11:21 PM, Alban wrote:
> From: Alban Bedel <albeu@free.fr>
>
> Normally compressed images have to be loaded at a different address to
> allow the decompressor to run. This add an option to let vmlinuz copy
> itself to the correct address from the normal vmlinux address.
>
> Signed-off-by: Alban Bedel <albeu@free.fr>
[...]
Just some grammar nitpicking...
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index b3c5bde..8074fc5 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -2961,6 +2961,14 @@ choice
> bool "Extend builtin kernel arguments with bootloader arguments"
> endchoice
>
> +config ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
> + bool "Load compressed images at the same address as uncompressed"
> + depends on SYS_SUPPORTS_ZBOOT
> + help
> + vmlinux and vmlinuz normally have different load addresses, with
> + this option vmlinuz expect to be loaded at the same address as
Expects.
[...]
MBR, Sergei
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] MIPS: Allow compressed images to be loaded at the usual address
2017-02-05 20:21 [PATCH] MIPS: Allow compressed images to be loaded at the usual address Alban
2017-02-06 8:52 ` Sergei Shtylyov
@ 2017-02-09 12:22 ` Jonas Gorski
2017-02-13 8:37 ` Alban
1 sibling, 1 reply; 5+ messages in thread
From: Jonas Gorski @ 2017-02-09 12:22 UTC (permalink / raw)
To: Alban; +Cc: MIPS Mailing List, Ralf Baechle, linux-kernel
Hi,
On 5 February 2017 at 21:21, Alban <albeu@free.fr> wrote:
> From: Alban Bedel <albeu@free.fr>
>
> Normally compressed images have to be loaded at a different address to
> allow the decompressor to run. This add an option to let vmlinuz copy
> itself to the correct address from the normal vmlinux address.
>
> Signed-off-by: Alban Bedel <albeu@free.fr>
> ---
> arch/mips/Kconfig | 8 ++++++++
> arch/mips/boot/compressed/head.S | 13 +++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index b3c5bde..8074fc5 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -2961,6 +2961,14 @@ choice
> bool "Extend builtin kernel arguments with bootloader arguments"
> endchoice
>
> +config ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
> + bool "Load compressed images at the same address as uncompressed"
> + depends on SYS_SUPPORTS_ZBOOT
> + help
> + vmlinux and vmlinuz normally have different load addresses, with
> + this option vmlinuz expect to be loaded at the same address as
> + vmlinux.
> +
> endmenu
Okay, it took me a while to understand the intention of this change. I
thought it was for supporting the case that VMLINUZ_LOAD_ADDRESS ==
VMLINUX_LOAD_ADDRESS, but it is indented for VMLINUZ_LOAD_ADDRESS !=
VMLINUX_LOAD_ADDRESS, but still being loaded at VMLINUX_LOAD_ADDRESS.
So I guess that this can only happen with vmlinuz.bin, as vmlinux's
ELF header will cause it to be loaded at the expected address (for
sane bootloaders at least).
> config LOCKDEP_SUPPORT
> diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
> index 409cb48..a215171 100644
> --- a/arch/mips/boot/compressed/head.S
> +++ b/arch/mips/boot/compressed/head.S
> @@ -25,6 +25,19 @@ start:
> move s2, a2
> move s3, a3
>
> +#ifdef CONFIG_ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
With a bit of BAL trickery you could easily detect this at runtime and
then conditionally copy without requiring any additional config
symbols. Then you aren't limited to being executed from
VMLINUX_LOAD_ADDRESS.
> + /* Move the text, data section and DTB to the correct address */
> + PTR_LA a0, .text
> + PTR_LI a1, VMLINUX_LOAD_ADDRESS
> + PTR_LA a2, _edata
> +0:
> + lw a3, 0(a1)
> + sw a3, 0(a0)
> + addiu a1, a1, 4
> + bne a2, a0, 0b
> + addiu a0, a0, 4
> +#endif
> +
> /* Clear BSS */
> PTR_LA a0, _edata
> PTR_LA a2, _end
Regards
Jonas
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] MIPS: Allow compressed images to be loaded at the usual address
2017-02-09 12:22 ` Jonas Gorski
@ 2017-02-13 8:37 ` Alban
2017-02-13 10:52 ` Jonas Gorski
0 siblings, 1 reply; 5+ messages in thread
From: Alban @ 2017-02-13 8:37 UTC (permalink / raw)
To: Jonas Gorski; +Cc: Aban Bedel, MIPS Mailing List, Ralf Baechle, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2816 bytes --]
On Thu, 9 Feb 2017 13:22:37 +0100
Jonas Gorski <jonas.gorski@gmail.com> wrote:
> Hi,
>
> On 5 February 2017 at 21:21, Alban <albeu@free.fr> wrote:
> > From: Alban Bedel <albeu@free.fr>
> >
> > Normally compressed images have to be loaded at a different address to
> > allow the decompressor to run. This add an option to let vmlinuz copy
> > itself to the correct address from the normal vmlinux address.
> >
> > Signed-off-by: Alban Bedel <albeu@free.fr>
> > ---
> > arch/mips/Kconfig | 8 ++++++++
> > arch/mips/boot/compressed/head.S | 13 +++++++++++++
> > 2 files changed, 21 insertions(+)
> >
> > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > index b3c5bde..8074fc5 100644
> > --- a/arch/mips/Kconfig
> > +++ b/arch/mips/Kconfig
> > @@ -2961,6 +2961,14 @@ choice
> > bool "Extend builtin kernel arguments with bootloader arguments"
> > endchoice
> >
> > +config ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
> > + bool "Load compressed images at the same address as uncompressed"
> > + depends on SYS_SUPPORTS_ZBOOT
> > + help
> > + vmlinux and vmlinuz normally have different load addresses, with
> > + this option vmlinuz expect to be loaded at the same address as
> > + vmlinux.
> > +
> > endmenu
>
> Okay, it took me a while to understand the intention of this change. I
> thought it was for supporting the case that VMLINUZ_LOAD_ADDRESS ==
> VMLINUX_LOAD_ADDRESS, but it is indented for VMLINUZ_LOAD_ADDRESS !=
> VMLINUX_LOAD_ADDRESS, but still being loaded at VMLINUX_LOAD_ADDRESS.
>
> So I guess that this can only happen with vmlinuz.bin, as vmlinux's
> ELF header will cause it to be loaded at the expected address (for
> sane bootloaders at least).
Yes, this is for bootloaders that use raw images. Having to configure
different load addresses for compressed and uncompressed images was just
too annoying.
> > config LOCKDEP_SUPPORT
> > diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
> > index 409cb48..a215171 100644
> > --- a/arch/mips/boot/compressed/head.S
> > +++ b/arch/mips/boot/compressed/head.S
> > @@ -25,6 +25,19 @@ start:
> > move s2, a2
> > move s3, a3
> >
> > +#ifdef CONFIG_ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
>
> With a bit of BAL trickery you could easily detect this at runtime and
> then conditionally copy without requiring any additional config
> symbols. Then you aren't limited to being executed from
> VMLINUX_LOAD_ADDRESS.
Could you expand a bit on what you mean with "BAL trickery"? I hoped
that it would be possible to auto detect the current running address,
but as I know very little about MIPS assembly I didn't found how that
could be done.
Alban
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] MIPS: Allow compressed images to be loaded at the usual address
2017-02-13 8:37 ` Alban
@ 2017-02-13 10:52 ` Jonas Gorski
0 siblings, 0 replies; 5+ messages in thread
From: Jonas Gorski @ 2017-02-13 10:52 UTC (permalink / raw)
To: Alban; +Cc: MIPS Mailing List, Ralf Baechle, linux-kernel
Hi,
On 13 February 2017 at 09:37, Alban <albeu@free.fr> wrote:
> On Thu, 9 Feb 2017 13:22:37 +0100
> Jonas Gorski <jonas.gorski@gmail.com> wrote:
>
>> Hi,
>>
>> On 5 February 2017 at 21:21, Alban <albeu@free.fr> wrote:
>> > From: Alban Bedel <albeu@free.fr>
>> >
>> > Normally compressed images have to be loaded at a different address to
>> > allow the decompressor to run. This add an option to let vmlinuz copy
>> > itself to the correct address from the normal vmlinux address.
>> >
>> > Signed-off-by: Alban Bedel <albeu@free.fr>
>> > ---
>> > arch/mips/Kconfig | 8 ++++++++
>> > arch/mips/boot/compressed/head.S | 13 +++++++++++++
>> > 2 files changed, 21 insertions(+)
>> >
>> > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
>> > index b3c5bde..8074fc5 100644
>> > --- a/arch/mips/Kconfig
>> > +++ b/arch/mips/Kconfig
>> > @@ -2961,6 +2961,14 @@ choice
>> > bool "Extend builtin kernel arguments with bootloader arguments"
>> > endchoice
>> >
>> > +config ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
>> > + bool "Load compressed images at the same address as uncompressed"
>> > + depends on SYS_SUPPORTS_ZBOOT
>> > + help
>> > + vmlinux and vmlinuz normally have different load addresses, with
>> > + this option vmlinuz expect to be loaded at the same address as
>> > + vmlinux.
>> > +
>> > endmenu
>>
>> Okay, it took me a while to understand the intention of this change. I
>> thought it was for supporting the case that VMLINUZ_LOAD_ADDRESS ==
>> VMLINUX_LOAD_ADDRESS, but it is indented for VMLINUZ_LOAD_ADDRESS !=
>> VMLINUX_LOAD_ADDRESS, but still being loaded at VMLINUX_LOAD_ADDRESS.
>>
>> So I guess that this can only happen with vmlinuz.bin, as vmlinux's
>> ELF header will cause it to be loaded at the expected address (for
>> sane bootloaders at least).
>
> Yes, this is for bootloaders that use raw images. Having to configure
> different load addresses for compressed and uncompressed images was just
> too annoying.
>
>> > config LOCKDEP_SUPPORT
>> > diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
>> > index 409cb48..a215171 100644
>> > --- a/arch/mips/boot/compressed/head.S
>> > +++ b/arch/mips/boot/compressed/head.S
>> > @@ -25,6 +25,19 @@ start:
>> > move s2, a2
>> > move s3, a3
>> >
>> > +#ifdef CONFIG_ZBOOT_VMLINUZ_AT_VMLINUX_LOAD_ADDRESS
>>
>> With a bit of BAL trickery you could easily detect this at runtime and
>> then conditionally copy without requiring any additional config
>> symbols. Then you aren't limited to being executed from
>> VMLINUX_LOAD_ADDRESS.
>
> Could you expand a bit on what you mean with "BAL trickery"? I hoped
> that it would be possible to auto detect the current running address,
> but as I know very little about MIPS assembly I didn't found how that
> could be done.
With BAL (branch and link) you can do a pc-relative jump, and the
current address will be stored in $ra. comparing it with the expected
address will give you the offset by which you were loaded. To quote
the lzma-loader from OpenWrt/Lede[1]:
la t0, __reloc_label # get linked address of label
bal __reloc_label # branch and link to label to
nop # get actual address
__reloc_label:
subu t0, ra, t0 # get reloc_delta
beqz t0, __reloc_done # if delta is 0 we are in the
right place
nop
/* Copy our code to the right place */
la t1, _code_start # get linked address of _code_start
la t2, _code_end # get linked address of _code_end
addu t0, t0, t1 # calculate actual address of
_code_start
__reloc_copy:
...
__reloc_done:
...
Regards
Jonas
[1] https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/ar71xx/image/lzma-loader/src/head.S;h=47a7c9bd6300ad92e6a0d426c5f44bc0f3e7e85f;hb=HEAD#l49
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-02-05 20:21 [PATCH] MIPS: Allow compressed images to be loaded at the usual address Alban
2017-02-06 8:52 ` Sergei Shtylyov
2017-02-09 12:22 ` Jonas Gorski
2017-02-13 8:37 ` Alban
2017-02-13 10:52 ` Jonas Gorski
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