[U-Boot] [PATCH v6 4/6] arm: spl: Allow board_init_r() to run with a larger stack
Tom Rini
trini at konsulko.com
Wed Mar 4 14:38:33 CET 2015
On Tue, Mar 03, 2015 at 08:23:23PM -0700, Simon Glass wrote:
> Hi Tom,
>
> On 3 March 2015 at 13:14, Tom Rini <trini at konsulko.com> wrote:
> > On Tue, Mar 03, 2015 at 12:04:16PM -0700, Simon Glass wrote:
> >> Hi Tom,
> >>
> >> On 3 March 2015 at 10:49, Tom Rini <trini at konsulko.com> wrote:
> >> > On Tue, Mar 03, 2015 at 08:03:00AM -0700, Simon Glass wrote:
> >> >
> >> >> At present SPL uses a single stack, either CONFIG_SPL_STACK or
> >> >> CONFIG_SYS_INIT_SP_ADDR. Since some SPL features (such as MMC and
> >> >> environment) require a lot of stack, some boards set CONFIG_SPL_STACK to
> >> >> point into SDRAM. They then set up SDRAM very early, before board_init_f(),
> >> >> so that the larger stack can be used.
> >> >>
> >> >> This is an abuse of lowlevel_init(). That function should only be used for
> >> >> essential start-up code which cannot be delayed. An example of a valid use is
> >> >> when only part of the SPL code is visible/executable, and the SoC must be set
> >> >> up so that board_init_f() can be reached. It should not be used for SDRAM
> >> >> init, console init, etc.
> >> >>
> >> >> Add a CONFIG_SPL_STACK_R option, which allows the stack to be moved to a new
> >> >> address before board_init_r() is called in SPL.
> >> >>
> >> >> The expected SPL flow (for CONFIG_SPL_FRAMEWORK) is documented in the README.
> >> >>
> >> >> Signed-off-by: Simon Glass <sjg at chromium.org>
> >> >> For version 1:
> >> >> Acked-by: Albert ARIBAUD <albert.u.boot at aribaud.net>
> >> >> Reviewed-by: Stefan Roese <sr at denx.de>
> >> >> Tested-by: Bo Shen <voice.shen at atmel.com>
> >> >> Acked-by: Bo Shen <voice.shen at atmel.com>
> >> >> Acked-by: Heiko Schocher <hs at denx.de>
> >> >> Tested-by: Heiko Schocher <hs at denx.de>
> >> >> ---
> >> >>
> >> >> Changes in v6: None
> >> >> Changes in v5:
> >> >> - Rebase to master
> >> >>
> >> >> Changes in v4:
> >> >> - Adjust README to mention that lowlevel_init() should have no stack
> >> >>
> >> >> Changes in v3: None
> >> >> Changes in v2:
> >> >> - Move docs to top-level README file and expand them to cover U-Boot proper
> >> >> - Add Kconfig settings
> >> >>
> >> >> Kconfig | 18 ++++++++++++++
> >> >> README | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >> >> arch/arm/lib/crt0.S | 13 +++++++---
> >> >> common/spl/spl.c | 35 +++++++++++++++++++++++++++
> >> >> 4 files changed, 132 insertions(+), 3 deletions(-)
> >> > [snip]
> >> >> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
> >> >> index 22df3e5..7939ced 100644
> >> >> --- a/arch/arm/lib/crt0.S
> >> >> +++ b/arch/arm/lib/crt0.S
> >> >> @@ -113,7 +113,14 @@ here:
> >> >> /* Set up final (full) environment */
> >> >>
> >> >> bl c_runtime_cpu_setup /* we still call old routine here */
> >> >> -
> >> >> +#endif
> >> >> +#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK)
> >> >> +# ifdef CONFIG_SPL_BUILD
> >> >> + /* Use a DRAM stack for the rest of SPL, if requested */
> >> >> + bl spl_relocate_stack_gd
> >> >> + cmp r0, #0
> >> >> + movne sp, r0
> >> >> +# endif
> >> >> ldr r0, =__bss_start /* this is auto-relocated! */
> >> >> ldr r1, =__bss_end /* this is auto-relocated! */
> >> >>
> >> >> @@ -124,9 +131,10 @@ clbss_l:cmp r0, r1 /* while not at end of BSS */
> >> >> addlo r0, r0, #4 /* move to next */
> >> >> blo clbss_l
> >> >>
> >> >> +#if ! defined(CONFIG_SPL_BUILD)
> >> >> bl coloured_LED_init
> >> >> bl red_led_on
> >> >> -
> >> >> +#endif
> >> >> /* call board_init_r(gd_t *id, ulong dest_addr) */
> >> >> mov r0, r9 /* gd_t */
> >> >> ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
> >> >> @@ -134,7 +142,6 @@ clbss_l:cmp r0, r1 /* while not at end of BSS */
> >> >> ldr pc, =board_init_r /* this is auto-relocated! */
> >> >>
> >> >> /* we should not return here. */
> >> >> -
> >> >> #endif
> >> >>
> >> >> ENDPROC(_main)
> >> >> diff --git a/common/spl/spl.c b/common/spl/spl.c
> >> >> index ded0f30..cd75bbc 100644
> >> >> --- a/common/spl/spl.c
> >> >> +++ b/common/spl/spl.c
> >> >> @@ -281,3 +281,38 @@ void preloader_console_init(void)
> >> >> spl_display_print();
> >> >> #endif
> >> >> }
> >> >> +
> >> >> +/**
> >> >> + * spl_relocate_stack_gd() - Relocate stack ready for board_init_r() execution
> >> >> + *
> >> >> + * Sometimes board_init_f() runs with a stack in SRAM but we want to use SDRAM
> >> >> + * for the main board_init_r() execution. This is typically because we need
> >> >> + * more stack space for things like the MMC sub-system.
> >> >> + *
> >> >> + * This function calculates the stack position, copies the global_data into
> >> >> + * place and returns the new stack position. The caller is responsible for
> >> >> + * setting up the sp register.
> >> >> + *
> >> >> + * @return new stack location, or 0 to use the same stack
> >> >> + */
> >> >> +ulong spl_relocate_stack_gd(void)
> >> >> +{
> >> >> +#ifdef CONFIG_SPL_STACK_R
> >> >> + gd_t *new_gd;
> >> >> + ulong ptr;
> >> >> +
> >> >> + /* Get stack position: use 8-byte alignment for ABI compliance */
> >> >> + ptr = CONFIG_SPL_STACK_R - sizeof(gd_t);
> >> >> + ptr &= ~7;
> >> >> + new_gd = (gd_t *)ptr;
> >> >> + memcpy(new_gd, (void *)gd, sizeof(gd_t));
> >> >> + gd = new_gd;
> >> >> +
> >> >> + /* Clear the BSS. */
> >> >> + memset(__bss_start, 0, __bss_end - __bss_start);
> >> >> +
> >> >> + return ptr;
> >> >> +#else
> >> >> + return 0;
> >> >> +#endif
> >> >> +}
> >> >
> >> > All of this _does_ move gd into where CONFIG_SPL_STACK_R points. It
> >> > does _not_ move the stack itself into where CONFIG_SPL_STACK_R points so
> >> > the big use case (am335x_boneblack for example where
> >> > CONFIG_SPL_ENV_SUPPORT is set) doesn't work and blows up as we overflow
> >> > the area for stack.
> >>
> >> OK I'll have to test more. What sort of problem should i see?
> >
> > We hang on entering env_reloc_spec() which is what puts some big sized
> > variables on the stack.
> >
> >> The return value from spl_relocate_stack_gd() should be shoved into
> >> sp. Does that not happen?
> >
> > It doesn't appear to be. I hadn't broken out the BBB with JTAG tho.
>
> I printed out the stack in board_init_r() and it looks right: 32MB
> above the base of SDRAM.
>
> Also I don't seem to get a crash in SPL. How do I make that happen? If
> I define CONFIG_SPL_USBETH_SUPPORT I get an error about the .data
> section not fitin in .sram for u-boot-spl.
With v5 at least, am335x_boneblack_config running on a BBB does it.
I'll try v6 this morning and see what's going on..
--
Tom
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