| Message ID | 20240503075619.394467-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 03c0f2c2b2220fc9cf8785cd7b61d3e71e24a366 |
| Headers | show |
| Series | [v2,1/2] powerpc/io: Avoid clang null pointer arithmetic warnings | expand |
On Fri, 03 May 2024 17:56:18 +1000, Michael Ellerman wrote: > With -Wextra clang warns about pointer arithmetic using a null pointer. > When building with CONFIG_PCI=n, that triggers a warning in the IO > accessors, eg: > > In file included from linux/arch/powerpc/include/asm/io.h:672: > linux/arch/powerpc/include/asm/io-defs.h:23:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] > 23 | DEF_PCI_AC_RET(inb, u8, (unsigned long port), (port), pio, port) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ... > linux/arch/powerpc/include/asm/io.h:591:53: note: expanded from macro '__do_inb' > 591 | #define __do_inb(port) readb((PCI_IO_ADDR)_IO_BASE + port); > | ~~~~~~~~~~~~~~~~~~~~~ ^ > > [...] Applied to powerpc/next. [1/2] powerpc/io: Avoid clang null pointer arithmetic warnings https://git.kernel.org/powerpc/c/03c0f2c2b2220fc9cf8785cd7b61d3e71e24a366 [2/2] powerpc/64: Set _IO_BASE to POISON_POINTER_DELTA not 0 for CONFIG_PCI=n https://git.kernel.org/powerpc/c/be140f1732b523947425aaafbe2e37b41b622d96 cheers
On Fri, 3 May 2024 at 13:26, Michael Ellerman <mpe@ellerman.id.au> wrote: > > With -Wextra clang warns about pointer arithmetic using a null pointer. > When building with CONFIG_PCI=n, that triggers a warning in the IO > accessors, eg: > > In file included from linux/arch/powerpc/include/asm/io.h:672: > linux/arch/powerpc/include/asm/io-defs.h:23:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] > 23 | DEF_PCI_AC_RET(inb, u8, (unsigned long port), (port), pio, port) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ... > linux/arch/powerpc/include/asm/io.h:591:53: note: expanded from macro '__do_inb' > 591 | #define __do_inb(port) readb((PCI_IO_ADDR)_IO_BASE + port); > | ~~~~~~~~~~~~~~~~~~~~~ ^ > > That is because when CONFIG_PCI=n, _IO_BASE is defined as 0. > > Although _IO_BASE is defined as plain 0, the cast (PCI_IO_ADDR) converts > it to void * before the addition with port happens. > > Instead the addition can be done first, and then the cast. The resulting > value will be the same, but avoids the warning, and also avoids void > pointer arithmetic which is apparently non-standard. > > Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> > Closes: https://lore.kernel.org/all/CA+G9fYtEh8zmq8k8wE-8RZwW-Qr927RLTn+KqGnq1F=ptaaNsA@mail.gmail.com > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> -- Linaro LKFT https://lkft.linaro.org
Naresh Kamboju <naresh.kamboju@linaro.org> writes: > On Fri, 3 May 2024 at 13:26, Michael Ellerman <mpe@ellerman.id.au> wrote: >> >> With -Wextra clang warns about pointer arithmetic using a null pointer. >> When building with CONFIG_PCI=n, that triggers a warning in the IO >> accessors, eg: >> >> In file included from linux/arch/powerpc/include/asm/io.h:672: >> linux/arch/powerpc/include/asm/io-defs.h:23:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] >> 23 | DEF_PCI_AC_RET(inb, u8, (unsigned long port), (port), pio, port) >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> ... >> linux/arch/powerpc/include/asm/io.h:591:53: note: expanded from macro '__do_inb' >> 591 | #define __do_inb(port) readb((PCI_IO_ADDR)_IO_BASE + port); >> | ~~~~~~~~~~~~~~~~~~~~~ ^ >> >> That is because when CONFIG_PCI=n, _IO_BASE is defined as 0. >> >> Although _IO_BASE is defined as plain 0, the cast (PCI_IO_ADDR) converts >> it to void * before the addition with port happens. >> >> Instead the addition can be done first, and then the cast. The resulting >> value will be the same, but avoids the warning, and also avoids void >> pointer arithmetic which is apparently non-standard. >> >> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> >> Closes: https://lore.kernel.org/all/CA+G9fYtEh8zmq8k8wE-8RZwW-Qr927RLTn+KqGnq1F=ptaaNsA@mail.gmail.com >> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > > Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Thanks. cheers
diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h index 08c550ed49be..ba2e13bb879d 100644 --- a/arch/powerpc/include/asm/io.h +++ b/arch/powerpc/include/asm/io.h @@ -585,12 +585,12 @@ __do_out_asm(_rec_outl, "stwbrx") #define __do_inw(port) _rec_inw(port) #define __do_inl(port) _rec_inl(port) #else /* CONFIG_PPC32 */ -#define __do_outb(val, port) writeb(val,(PCI_IO_ADDR)_IO_BASE+port); -#define __do_outw(val, port) writew(val,(PCI_IO_ADDR)_IO_BASE+port); -#define __do_outl(val, port) writel(val,(PCI_IO_ADDR)_IO_BASE+port); -#define __do_inb(port) readb((PCI_IO_ADDR)_IO_BASE + port); -#define __do_inw(port) readw((PCI_IO_ADDR)_IO_BASE + port); -#define __do_inl(port) readl((PCI_IO_ADDR)_IO_BASE + port); +#define __do_outb(val, port) writeb(val,(PCI_IO_ADDR)(_IO_BASE+port)); +#define __do_outw(val, port) writew(val,(PCI_IO_ADDR)(_IO_BASE+port)); +#define __do_outl(val, port) writel(val,(PCI_IO_ADDR)(_IO_BASE+port)); +#define __do_inb(port) readb((PCI_IO_ADDR)(_IO_BASE + port)); +#define __do_inw(port) readw((PCI_IO_ADDR)(_IO_BASE + port)); +#define __do_inl(port) readl((PCI_IO_ADDR)(_IO_BASE + port)); #endif /* !CONFIG_PPC32 */ #ifdef CONFIG_EEH @@ -606,12 +606,12 @@ __do_out_asm(_rec_outl, "stwbrx") #define __do_writesw(a, b, n) _outsw(PCI_FIX_ADDR(a),(b),(n)) #define __do_writesl(a, b, n) _outsl(PCI_FIX_ADDR(a),(b),(n)) -#define __do_insb(p, b, n) readsb((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) -#define __do_insw(p, b, n) readsw((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) -#define __do_insl(p, b, n) readsl((PCI_IO_ADDR)_IO_BASE+(p), (b), (n)) -#define __do_outsb(p, b, n) writesb((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) -#define __do_outsw(p, b, n) writesw((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) -#define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)_IO_BASE+(p),(b),(n)) +#define __do_insb(p, b, n) readsb((PCI_IO_ADDR)(_IO_BASE+(p)), (b), (n)) +#define __do_insw(p, b, n) readsw((PCI_IO_ADDR)(_IO_BASE+(p)), (b), (n)) +#define __do_insl(p, b, n) readsl((PCI_IO_ADDR)(_IO_BASE+(p)), (b), (n)) +#define __do_outsb(p, b, n) writesb((PCI_IO_ADDR)(_IO_BASE+(p)),(b),(n)) +#define __do_outsw(p, b, n) writesw((PCI_IO_ADDR)(_IO_BASE+(p)),(b),(n)) +#define __do_outsl(p, b, n) writesl((PCI_IO_ADDR)(_IO_BASE+(p)),(b),(n)) #define __do_memset_io(addr, c, n) \ _memset_io(PCI_FIX_ADDR(addr), c, n)
With -Wextra clang warns about pointer arithmetic using a null pointer. When building with CONFIG_PCI=n, that triggers a warning in the IO accessors, eg: In file included from linux/arch/powerpc/include/asm/io.h:672: linux/arch/powerpc/include/asm/io-defs.h:23:1: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 23 | DEF_PCI_AC_RET(inb, u8, (unsigned long port), (port), pio, port) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... linux/arch/powerpc/include/asm/io.h:591:53: note: expanded from macro '__do_inb' 591 | #define __do_inb(port) readb((PCI_IO_ADDR)_IO_BASE + port); | ~~~~~~~~~~~~~~~~~~~~~ ^ That is because when CONFIG_PCI=n, _IO_BASE is defined as 0. Although _IO_BASE is defined as plain 0, the cast (PCI_IO_ADDR) converts it to void * before the addition with port happens. Instead the addition can be done first, and then the cast. The resulting value will be the same, but avoids the warning, and also avoids void pointer arithmetic which is apparently non-standard. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Closes: https://lore.kernel.org/all/CA+G9fYtEh8zmq8k8wE-8RZwW-Qr927RLTn+KqGnq1F=ptaaNsA@mail.gmail.com Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/include/asm/io.h | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) v2: New.