alexcekay opened a new pull request, #16019:
URL: https://github.com/apache/nuttx/pull/16019
## Summary
Add `no_builtin` for `memcpy/memset` to the startup code of boards
with `CONFIG_ARCH_RAMFUNCS`, because certain compilers call `memcpy/memset`
instead of the explicit `for` loop. This will cause a crash if
`memcpy/memset`
are mapped to RAM because the function that copies them to RAM is called
later,
resulting in undefined code being executed.
## Impact
- Using `memcpy/memset` as RAMFUNCS is possible
## Testing
- The problem was observed with the following compiler: `arm-none-eabi-gcc
(15:13.2.rel1-2) 13.2.1 20231009`
- This is the default `arm-none-eabi-gcc` that is currently used on Ubuntu
Noble
- Was tested with a STM32F765
### Testing logs before
Before the patch there was a call to `memset` in the startup:
```
0 0x000006c4 in memset (s=0x20021b00 <g_intstackalloc>, c=c@entry=0,
n=91844) at /home/alex/[...]/nuttx/libs/libc/string/lib_memset.c:73
#1 0x0800a804 in __start () at
/home/alex/[...]/nuttx/arch/arm/src/stm32f7/stm32_start.c:194
#2 0x08000306 in ?? ()
```
As can be seen the address of `memset` it is in non initialized storage.
### Testing logs after
After the patch there is no more call to `memset/memcpy`:
```
#0 __start () at
/home/alex/[...]/nuttx/arch/arm/src/stm32f7/stm32_start.c:196
#1 0x08000306 in ?? ()
```
```
0x0800a834 <+80>: bl 0x814039c <stm32_boardinitialize()>
0x0800a838 <+84>: bl 0x800a884 <up_enable_icache>
0x0800a83c <+88>: bl 0x800a8ac <up_enable_dcache>
0x0800a840 <+92>: bl 0x800b894 <arm_earlyserialinit>
0x0800a844 <+96>: bl 0x800d290 <nx_start>
=> 0x0800a848 <+100>: str.w r1, [r3], #4
0x0800a84c <+104>: b.n 0x800a7f0 <__start+12>
0x0800a84e <+106>: ldr.w r0, [r2], #4
0x0800a852 <+110>: str.w r0, [r3], #4
0x0800a856 <+114>: b.n 0x800a7fa <__start+22>
0x0800a858 <+116>: ldr.w r0, [r2], #4
0x0800a85c <+120>: str.w r0, [r3], #4
0x0800a860 <+124>: b.n 0x800a804 <__start+32>
```
This way a successful boot is possible.
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