Re: [PATCH v2] OMAP: use fncpy to copy the PM code functions to SRAM

[Dave Martin <dave.martin@linaro.org>]

Hi there, I just spotted a couple of things merging your patch...

On Tue, Jan 18, 2011 at 12:02 PM,  <jean.pihet@newoldbits.com> wrote:
> From: Jean Pihet <j-pihet@ti.com>
>
> The new fncpy API is better suited for copying some
> code to SRAM at runtime. This patch changes the ad-hoc
> code to the more generic fncpy API.
>
> Tested OK on OMAP3 in low power modes (RET/OFF)
> using omap2plus_defconfig with !CONFIG_THUMB2_KERNEL.
> Compile tested on OMAP1/2 using omap1_defconfig.
>
> Signed-off-by: Jean Pihet <j-pihet@ti.com>
> ---
>  arch/arm/mach-omap1/pm.h               |    6 +++---
>  arch/arm/mach-omap1/sleep.S            |    3 +++
>  arch/arm/mach-omap1/sram.S             |    1 +
>  arch/arm/mach-omap2/pm.h               |    2 +-
>  arch/arm/mach-omap2/sleep24xx.S        |    2 ++
>  arch/arm/mach-omap2/sleep34xx.S        |    2 ++
>  arch/arm/mach-omap2/sram242x.S         |    3 +++
>  arch/arm/mach-omap2/sram243x.S         |    3 +++
>  arch/arm/mach-omap2/sram34xx.S         |    1 +
>  arch/arm/plat-omap/include/plat/sram.h |   14 +++++++++++++-
>  arch/arm/plat-omap/sram.c              |   14 +++++++++-----
>  11 files changed, 41 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/mach-omap1/pm.h b/arch/arm/mach-omap1/pm.h
> index 56a6479..cd926dc 100644
> --- a/arch/arm/mach-omap1/pm.h
> +++ b/arch/arm/mach-omap1/pm.h
> @@ -123,9 +123,9 @@ extern void allow_idle_sleep(void);
>  extern void omap1_pm_idle(void);
>  extern void omap1_pm_suspend(void);
>
> -extern void omap7xx_cpu_suspend(unsigned short, unsigned short);
> -extern void omap1510_cpu_suspend(unsigned short, unsigned short);
> -extern void omap1610_cpu_suspend(unsigned short, unsigned short);
> +extern void omap7xx_cpu_suspend(unsigned long, unsigned long);
> +extern void omap1510_cpu_suspend(unsigned long, unsigned long);
> +extern void omap1610_cpu_suspend(unsigned long, unsigned long);
>  extern void omap7xx_idle_loop_suspend(void);
>  extern void omap1510_idle_loop_suspend(void);
>  extern void omap1610_idle_loop_suspend(void);
> diff --git a/arch/arm/mach-omap1/sleep.S b/arch/arm/mach-omap1/sleep.S
> index ef771ce..c875bdc 100644
> --- a/arch/arm/mach-omap1/sleep.S
> +++ b/arch/arm/mach-omap1/sleep.S
> @@ -58,6 +58,7 @@
>  */
>
>  #if defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP850)
> +       .align  3
>  ENTRY(omap7xx_cpu_suspend)
>
>        @ save registers on stack
> @@ -137,6 +138,7 @@ ENTRY(omap7xx_cpu_suspend_sz)
>  #endif /* CONFIG_ARCH_OMAP730 || CONFIG_ARCH_OMAP850 */
>
>  #ifdef CONFIG_ARCH_OMAP15XX
> +       .align  3
>  ENTRY(omap1510_cpu_suspend)
>
>        @ save registers on stack
> @@ -211,6 +213,7 @@ ENTRY(omap1510_cpu_suspend_sz)
>  #endif /* CONFIG_ARCH_OMAP15XX */
>
>  #if defined(CONFIG_ARCH_OMAP16XX)
> +       .align  3
>  ENTRY(omap1610_cpu_suspend)
>
>        @ save registers on stack
> diff --git a/arch/arm/mach-omap1/sram.S b/arch/arm/mach-omap1/sram.S
> index 7724e52..692587d 100644
> --- a/arch/arm/mach-omap1/sram.S
> +++ b/arch/arm/mach-omap1/sram.S
> @@ -18,6 +18,7 @@
>  /*
>  * Reprograms ULPD and CKCTL.
>  */
> +       .align  3
>  ENTRY(omap1_sram_reprogram_clock)
>        stmfd   sp!, {r0 - r12, lr}             @ save registers on stack
>
> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> index 1c1b0ab..39580e6 100644
> --- a/arch/arm/mach-omap2/pm.h
> +++ b/arch/arm/mach-omap2/pm.h
> @@ -92,7 +92,7 @@ extern void omap24xx_idle_loop_suspend(void);
>  extern void omap24xx_cpu_suspend(u32 dll_ctrl, void __iomem *sdrc_dlla_ctrl,
>                                        void __iomem *sdrc_power);
>  extern void omap34xx_cpu_suspend(u32 *addr, int save_state);
> -extern void save_secure_ram_context(u32 *addr);
> +extern int save_secure_ram_context(u32 *addr);
>  extern void omap3_save_scratchpad_contents(void);
>
>  extern unsigned int omap24xx_idle_loop_suspend_sz;
> diff --git a/arch/arm/mach-omap2/sleep24xx.S b/arch/arm/mach-omap2/sleep24xx.S
> index c7780cc..b5071a4 100644
> --- a/arch/arm/mach-omap2/sleep24xx.S
> +++ b/arch/arm/mach-omap2/sleep24xx.S
> @@ -47,6 +47,7 @@
>  * Note: This code get's copied to internal SRAM at boot. When the OMAP
>  *      wakes up it continues execution at the point it went to sleep.
>  */
> +       .align  3
>  ENTRY(omap24xx_idle_loop_suspend)
>        stmfd   sp!, {r0, lr}           @ save registers on stack
>        mov     r0, #0                  @ clear for mcr setup
> @@ -82,6 +83,7 @@ ENTRY(omap24xx_idle_loop_suspend_sz)
>  * The DLL load value is not kept in RETENTION or OFF. It needs to be restored
>  * at wake
>  */
> +       .align  3
>  ENTRY(omap24xx_cpu_suspend)
>        stmfd   sp!, {r0 - r12, lr}     @ save registers on stack
>        mov     r3, #0x0                @ clear for mcr call
> diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
> index 98d8232..951a0be 100644
> --- a/arch/arm/mach-omap2/sleep34xx.S
> +++ b/arch/arm/mach-omap2/sleep34xx.S
> @@ -118,6 +118,7 @@ ENTRY(enable_omap3630_toggle_l2_on_restore)
>
>        .text
>  /* Function to call rom code to save secure ram context */
> +       .align  3
>  ENTRY(save_secure_ram_context)
>        stmfd   sp!, {r1-r12, lr}       @ save registers on stack
>        adr     r3, api_params          @ r3 points to parameters
> @@ -169,6 +170,7 @@ ENTRY(save_secure_ram_context_sz)
>  *   depending on the low power mode (non-OFF vs OFF modes),
>  *   cf. 'Resume path for xxx mode' comments.
>  */
> +       .align  3
>  ENTRY(omap34xx_cpu_suspend)
>        stmfd   sp!, {r0-r12, lr}       @ save registers on stack
>
> diff --git a/arch/arm/mach-omap2/sram242x.S b/arch/arm/mach-omap2/sram242x.S
> index 055310c..ff9b9db 100644
> --- a/arch/arm/mach-omap2/sram242x.S
> +++ b/arch/arm/mach-omap2/sram242x.S
> @@ -39,6 +39,7 @@
>
>        .text
>
> +       .align  3
>  ENTRY(omap242x_sram_ddr_init)
>        stmfd   sp!, {r0 - r12, lr}     @ save registers on stack
>
> @@ -143,6 +144,7 @@ ENTRY(omap242x_sram_ddr_init_sz)
>  * r0 = [PRCM_FULL | PRCM_HALF] r1 = SDRC_DLLA_CTRL value r2 = [DDR | SDR]
>  * PRCM_FULL = 2, PRCM_HALF = 1, DDR = 1, SDR = 0
>  */
> +       .align  3
>  ENTRY(omap242x_sram_reprogram_sdrc)
>        stmfd   sp!, {r0 - r10, lr}     @ save registers on stack
>        mov     r3, #0x0                @ clear for mrc call
> @@ -238,6 +240,7 @@ ENTRY(omap242x_sram_reprogram_sdrc_sz)
>  /*
>  * Set dividers and pll. Also recalculate DLL value for DDR and unlock mode.
>  */
> +       .align  3
>  ENTRY(omap242x_sram_set_prcm)
>        stmfd   sp!, {r0-r12, lr}       @ regs to stack
>        adr     r4, pbegin              @ addr of preload start
> diff --git a/arch/arm/mach-omap2/sram243x.S b/arch/arm/mach-omap2/sram243x.S
> index f900758..7673020 100644
> --- a/arch/arm/mach-omap2/sram243x.S
> +++ b/arch/arm/mach-omap2/sram243x.S
> @@ -39,6 +39,7 @@
>
>        .text
>
> +       .align  3
>  ENTRY(omap243x_sram_ddr_init)
>        stmfd   sp!, {r0 - r12, lr}     @ save registers on stack
>
> @@ -143,6 +144,7 @@ ENTRY(omap243x_sram_ddr_init_sz)
>  * r0 = [PRCM_FULL | PRCM_HALF] r1 = SDRC_DLLA_CTRL value r2 = [DDR | SDR]
>  * PRCM_FULL = 2, PRCM_HALF = 1, DDR = 1, SDR = 0
>  */
> +       .align  3
>  ENTRY(omap243x_sram_reprogram_sdrc)
>        stmfd   sp!, {r0 - r10, lr}     @ save registers on stack
>        mov     r3, #0x0                @ clear for mrc call
> @@ -238,6 +240,7 @@ ENTRY(omap243x_sram_reprogram_sdrc_sz)
>  /*
>  * Set dividers and pll. Also recalculate DLL value for DDR and unlock mode.
>  */
> +       .align  3
>  ENTRY(omap243x_sram_set_prcm)
>        stmfd   sp!, {r0-r12, lr}       @ regs to stack
>        adr     r4, pbegin              @ addr of preload start
> diff --git a/arch/arm/mach-omap2/sram34xx.S b/arch/arm/mach-omap2/sram34xx.S
> index 7f893a2..25011ca 100644
> --- a/arch/arm/mach-omap2/sram34xx.S
> +++ b/arch/arm/mach-omap2/sram34xx.S
> @@ -111,6 +111,7 @@
>  * since it will cause the ARM MMU to attempt to walk the page tables.
>  * These crashes may be intermittent.
>  */
> +       .align  3
>  ENTRY(omap3_sram_configure_core_dpll)
>        stmfd   sp!, {r1-r12, lr}       @ store regs to stack
>
> diff --git a/arch/arm/plat-omap/include/plat/sram.h b/arch/arm/plat-omap/include/plat/sram.h
> index 9967d5e..d673f2c 100644
> --- a/arch/arm/plat-omap/include/plat/sram.h
> +++ b/arch/arm/plat-omap/include/plat/sram.h
> @@ -12,7 +12,19 @@
>  #define __ARCH_ARM_OMAP_SRAM_H
>
>  #ifndef __ASSEMBLY__
> -extern void * omap_sram_push(void * start, unsigned long size);
> +#include <asm/fncpy.h>
> +
> +extern void *omap_sram_push_address(unsigned long size);
> +
> +/* Macro to push a function to the internal SRAM, using the fncpy API */
> +#define omap_sram_push(funcp, size) ({                         \
> +       typeof(&funcp) _res = NULL;                             \

1) For fncpy() itself, I decided not to take the address of funcp
inside the macro: the reason for this was that if you do this, the
macro will silently do something silly if called with a function
pointer instead of the function itself -- i.e., some memory starting
at the stored function pointer itself will be copied instead of the
function body.

Forcing the caller to supply the '&' is a bit ugly, but I decided it
was preferable from a safety standpoint.

This doesn't necessarily mean that omap_sram_push can't add the '&',
but if you do, you need to be careful how the macro is called.  It
will work for all existing uses of omap_sram_push, IIUC.

2) Should this be &(funcp)?  This will only matter for pretty weird
uses though.  Currently most weird uses won't work properly anyway,
because of (1).  So this might not be much of a concern.

> +       void *_sram_address = omap_sram_push_address(size);     \
> +       if (_sram_address)                                      \
> +               _res = fncpy(_sram_address, &funcp, size);      \

&(funcp)

(see (2))

Cheers
---Dave
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