On Fri, Feb 17, 2023 at 06:51:24PM +0100, Ahmad Fatoum wrote: > The barebox stack is always located at a fixed offset from the end of > SDRAM. To determine end of SDRAM, barebox may need a stack setup, so > at that early time, either stack pointer set up by BootROM is reused > or we set up a temporary stack on some on-chip SRAM . > > On STM32MP1, TF-A runs after BootROM, so barebox runs in normal world > without prepared stack and TF-A is located on on-chip SRAM. > > So what we did so far was have a small stack of 64 bytes starting behind > end of barebox image to cover the first function call to determine > actual memory size. This may have been chosen that small with the thought > that an overflow would give an error message anyway, because of failed > decompression. An overflow of exactly 4 bytes overwrites just the barebox > proper image size though located at the end of the barebox image, thereby > overflowing the size and leading to out-of-bounds access during decompression > in 1 of 4 cases depending on barebox size, because we align barebox > proper size to 16 bytes... > > Let's just use a fully sized stack even in the early state. That's > usually 32K and we expect a barebox loaded into DRAM to always have > that much bytes following it. Another way would've been to use > some of the other SRAMs, but I decided to leave those alone, as not > to clobber data used by the coprocessor, when reloading barebox. > > Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > --- > arch/arm/mach-stm32mp/include/mach/entry.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied, thanks Sascha > > diff --git a/arch/arm/mach-stm32mp/include/mach/entry.h b/arch/arm/mach-stm32mp/include/mach/entry.h > index f8d981cca7cd..8d3adb4bdaf9 100644 > --- a/arch/arm/mach-stm32mp/include/mach/entry.h > +++ b/arch/arm/mach-stm32mp/include/mach/entry.h > @@ -11,7 +11,7 @@ static __always_inline void stm32mp_cpu_lowlevel_init(void) > unsigned long stack_top; > arm_cpu_lowlevel_init(); > > - stack_top = (unsigned long)__image_end + get_runtime_offset() + 64; > + stack_top = (unsigned long)__image_end + get_runtime_offset() + CONFIG_STACK_SIZE; > stack_top = ALIGN(stack_top, 16); > arm_setup_stack(stack_top); > } > -- > 2.30.2 > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
