| Message ID | 20210915035227.630204-2-linux@roeck-us.net (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Introduce and use absolute_pointer macro | expand |
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> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Gr{oetje,eeting}s, Geert
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? Gr{oetje,eeting}s, Geert
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
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) + #ifndef OPTIMIZER_HIDE_VAR /* Make the optimizer believe the variable can be manipulated arbitrarily. */ #define OPTIMIZER_HIDE_VAR(var) \
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(+)