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[nrf fromlist] pre-stack hook for S2RAM resume bootloader support #3357

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[nrf fromlist] pre-stack hook for S2RAM resume bootloader support #3357

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4426f7f
Revert "[nrf fromlist] arch: Allow to specify memory for S2RAM resume"
nvlsianpu Oct 2, 2025
8263c98
[nrf fromlist] arch/arm: introduce the pre-stack init hook
nvlsianpu Oct 2, 2025
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7 changes: 7 additions & 0 deletions arch/arm/Kconfig
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Expand Up @@ -144,6 +144,13 @@ config ARM_ON_EXIT_CPU_IDLE
observed on some SoCs caused by a memory access following WFI/WFE
instructions.

config SOC_PRE_RAM_HOOK
bool "include cpu start hook"
depends on CPU_CORTEX_M
help
This hooks run almost after startup - even before any stack is initiated
or RAM is accessed.

rsource "core/Kconfig"
rsource "core/Kconfig.vfp"

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20 changes: 8 additions & 12 deletions arch/arm/core/cortex_m/reset.S
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Expand Up @@ -35,6 +35,10 @@ GTEXT(z_arm_init_arch_hw_at_boot)
#if defined(CONFIG_PM_S2RAM)
GTEXT(arch_pm_s2ram_resume)
#endif
#if defined(CONFIG_SOC_PRE_RAM_HOOK)
GTEXT(soc_pre_ram_hook)
#endif


/*
* PACBTI Mask for CONTROL register:
Expand Down Expand Up @@ -100,18 +104,11 @@ SECTION_SUBSEC_FUNC(TEXT,_reset_section,__start)

#endif /* CONFIG_INIT_ARCH_HW_AT_BOOT */

#if defined(CONFIG_SOC_PRE_RAM_HOOK)
/* Call custom code that executes before any stack is set up or RAM memory is accessed */
bl soc_pre_ram_hook
#endif
#if defined(CONFIG_PM_S2RAM)
#if DT_NODE_EXISTS(DT_NODELABEL(pm_s2ram_stack)) &&\
DT_NODE_HAS_COMPAT(DT_NODELABEL(pm_s2ram_stack), zephyr_memory_region)
/* In certain scenarios, the interrupt stack is actually not safe to overwrite.
* For example, when MCUboot is used, the bootloader's "z_interrupt_stack" and the
* loaded image's "z_interrupt_stacks" are NOT at the same address, and writing to
* the former would corrupt unrelated data from the loaded image. To support such
* scenarios, if the Device Tree provides a specially named "zephyr,memory-region",
* use it as the stack to run arch_pm_s2ram_resume instead of the interrupt stack.
*/
ldr r0, =DT_REG_ADDR(DT_NODELABEL(pm_s2ram_stack)) + DT_REG_SIZE(DT_NODELABEL(pm_s2ram_stack))
#else
/*
* Temporarily set MSP to interrupt stack so that arch_pm_s2ram_resume can
* use stack for calling pm_s2ram_mark_check_and_clear.
Expand All @@ -124,7 +121,6 @@ SECTION_SUBSEC_FUNC(TEXT,_reset_section,__start)
* a short while, there is no change in behavior in either of the paths.
*/
ldr r0, =z_interrupt_stacks + CONFIG_ISR_STACK_SIZE + MPU_GUARD_ALIGN_AND_SIZE
#endif
msr msp, r0

bl arch_pm_s2ram_resume
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5 changes: 0 additions & 5 deletions subsys/pm/Kconfig
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Expand Up @@ -41,11 +41,6 @@ config PM_S2RAM
When enabled on Cortex-M, and a 'zephyr,memory-region' compatible node with nodelabel
'pm_s2ram' is defined in DT, _cpu_context symbol (located in arch/arm/core/cortex_m/pm_s2ram.c)
is placed in linker section given by 'zephyr,memory-region' property of aforementioned node.
Additionally on Cortex-M, if a 'zephyr,memory-region' compatible node with nodelabel
'pm_s2ram_stack' is defined in DT, this region will be used as a temporary program stack
for the S2RAM resume logic. The assembly reset handling code itself makes a single push of
the return address, but the SoC-specific function (pm_s2ram_mark_check_and_clear) must be
analyzed to determine the required stack size.

config PM_S2RAM_CUSTOM_MARKING
bool "Use custom marking functions"
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