On Sat, Dec 18, 2021 at 09:13:57PM +0100, Paul Menzel wrote:
Dear Kevin,
Am 18.12.21 um 19:10 schrieb Kevin O'Connor:
Use a different definition for the linker script symbol to avoid a gcc warning.
What GCC version did you use, and which warning is it exactly?
$ gcc --version gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)
src/post.c: In function 'reloc_preinit': src/post.c:248:34: warning: array subscript 'u32 {aka unsigned int}[0]' is partly outside array bounds of 'char[1]' [-Warray-bounds] 248 | *((u32*)(dest + *reloc)) += delta; | ^~ In file included from src/biosvar.h:11, from src/post.c:8: src/post.c:278:26: note: while referencing 'code32flat_start' 278 | updateRelocs(VSYMBOL(code32flat_start), VSYMBOL(_reloc_init_start) | ^~~~~~~~~~~~~~~~ src/memmap.h:18:36: note: in definition of macro 'SYMBOL' 18 | #define SYMBOL(SYM) ({ extern char SYM; (u32)&SYM; }) | ^~~
Signed-off-by: Kevin O'Connor kevin@koconnor.net
src/memmap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/memmap.h b/src/memmap.h index 22bd4bc..32ca265 100644 --- a/src/memmap.h +++ b/src/memmap.h @@ -15,7 +15,7 @@ static inline void *memremap(u32 addr, u32 len) { } // Return the value of a linker script symbol (see scripts/layoutrom.py) -#define SYMBOL(SYM) ({ extern char SYM; (u32)&SYM; }) +#define SYMBOL(SYM) ({ extern char SYM[]; (u32)SYM; }) #define VSYMBOL(SYM) ((void*)SYMBOL(SYM)) #endif // memmap.h
gcc (Debian 11.2.0-13) 11.2.0 still shows a lot of:
Compile checking out/src/fw/smm.o In file included from src/fw/smm.c:18: src/fw/smm.c: In function 'smm_save_and_copy': src/string.h:23:16: warning: '__builtin_memcpy' offset [0, 511] is outof the bounds [0, 0] [-Warray-bounds] 23 | #define memcpy __builtin_memcpy src/fw/smm.c:148:5: note: in expansion of macro 'memcpy' 148 | memcpy(&smm->cpu, &initsmm->cpu, sizeof(smm->cpu)); | ^~~~~~
Yes - I see that as well in smm.c. Alas, I don't have a fix for it. It seems to me that gcc is producing bogus warnings here. It looks like anything of the form "memcpy((void*)0x1234, p, n)" where n is greater than 8 produces this warning. It's a requirement to memcpy to a physical memory address. Disabling the warning would require adding both "-Wno-array-bounds -Wno-stringop-overflow" to the build.
Maybe someone else has an idea on how to suppress this warning.
-Kevin