Messages in this thread | | | Subject | Re: [PATCH v2 1/4] compiler.h: Introduce absolute_pointer macro | From | Guenter Roeck <> | Date | Wed, 15 Sep 2021 07:03:26 -0700 |
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On 9/15/21 12:13 AM, Geert Uytterhoeven wrote: > Hi Günter, > > On Wed, Sep 15, 2021 at 5:52 AM Guenter Roeck <linux@roeck-us.net> wrote: >> absolute_pointer() disassociates a pointer from its originating symbol >> type and context. Use it to prevent compiler warnings/errors such as >> >> drivers/net/ethernet/i825xx/82596.c: In function 'i82596_probe': >> ./arch/m68k/include/asm/string.h:72:25: error: >> '__builtin_memcpy' reading 6 bytes from a region of size 0 >> [-Werror=stringop-overread] >> >> Such warnings may be reported by gcc 11.x for string and memory operations >> on fixed addresses. >> >> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> >> Signed-off-by: Guenter Roeck <linux@roeck-us.net> >> --- >> v2: No change >> >> include/linux/compiler.h | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/include/linux/compiler.h b/include/linux/compiler.h >> index b67261a1e3e9..3d5af56337bd 100644 >> --- a/include/linux/compiler.h >> +++ b/include/linux/compiler.h >> @@ -188,6 +188,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, >> (typeof(ptr)) (__ptr + (off)); }) >> #endif >> >> +#define absolute_pointer(val) RELOC_HIDE((void *)(val), 0) > > I guess we're not worried about "val" being evaluated multiple > times inside RELOC_HIDE(), as this is mainly intended for constants? >
No, we are not. It is quite similar to RELOC_HIDE() in that regard.
Guenter
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