On Fri, Jun 03, 2022 at 09:40:07AM +0200, Arnd Bergmann wrote:
On Fri, Jun 3, 2022 at 4:03 AM Naresh Kamboju naresh.kamboju@linaro.org wrote:
inlined from 'setup_arch' at arch/arm64/kernel/setup.c:350:2:arch/arm64/kernel/setup.c:225:56: warning: array subscript -1 is outside array bounds of 'char[]' [-Warray-bounds] 225 | kernel_code.end = __pa_symbol(__init_begin - 1);
Is this the only warning of this type that you get for arm64?
There are a handful of those subscript warnings. Looking at v5.19-rc1 defconfig, using the kernel.org GCC 12.1.0 cross toolchain:
| [mark@lakrids:~/src/linux]% usekorg 12.1.0 make ARCH=arm64 CROSS_COMPILE=aarch64-linux- -j50 2>&1 | grep -A1 subscript | arch/arm64/kernel/setup.c:225:56: warning: array subscript -1 is outside array bounds of 'char[]' [-Warray-bounds] | 225 | kernel_code.end = __pa_symbol(__init_begin - 1); | -- | arch/arm64/kernel/setup.c:227:48: warning: array subscript -1 is outside array bounds of 'char[]' [-Warray-bounds] | 227 | kernel_data.end = __pa_symbol(_end - 1); | -- | arch/arm64/kernel/hibernate.c:94:65: warning: array subscript -1 is outside array bounds of 'const void[]' [-Warray-bounds] | 94 | unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
The last of those can't have the `- 1` pulled out, but we could stuff a RELOC_HIDE() in there, as __pa_symbol() has internally.
Ideally we'd rework the section markers to not have this problem, either rethinking the way we mark them as flexible arrays, or giving them accessors, e.g.
#define va_init_begin() RELOC_HIDE((unsigned long)__init_begin)
... which'd be a pain, but at least it'd solve this generally.
I think the easy fix would be to reword this line to
kernel_code.end = __pa_symbol(__init_begin) - 1;
I agree that'd work for the __pa_symbol() cases.
For consistency it might be worth using RELOC_HIDE(), e.g.
kernel_code.end = __pa_symbol(RELOC_HIDE(__init_begin)) - 1);
... which IIUC should do the trick.
Thanks, Mark.