Hi Paul, On Fri, 9 Jun 2017 17:26:38 -0700, Paul Burton wrote: > Replace the macro definition of __cmpxchg() with an inline function, > which is easier to read & modify. The cmpxchg() & cmpxchg_local() macros > are adjusted to call the new __cmpxchg() function. > > Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx> > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> > Cc: linux-mips@xxxxxxxxxxxxxx I think this patch is breaking user space for me. I say "think" because it is a bit tricky to bisect for the few patches previous to this one since they won't compile cleanly for me (due to this https://www.spinics.net/lists/mips/msg68727.html). I have a Cavium Octeon 5010 MIPS64 CPU on a custom board, have been running it for years running various kernel versions. Linux-4.13 breaks for me, and I bisected back to this change. What I see is user space bomb strait after boot with console messages like this: mount[37] killed because of sig - 11 STACK DUMP: CPU: 0 PID: 37 Comm: mount Not tainted 4.13.0-uc0 #8 task: 8000000007d14200 task.stack: 8000000007f18000 $ 0 : 0000000000000000 000000ffffd23f70 000000000000001a 000000000001a7d0 $ 4 : 0000000125af9760 0000000125af9718 0000000125af9748 0000000000000001 $ 8 : 2f2f2f2f2f2f2f2f 8101010101010100 0000000000000000 00000000ffffffff $12 : 000000fff79f6000 000000fff7980f00 000000fff79887d8 0000000000000018 $16 : 0000000125af9718 0000000125af9760 0000000125af9748 0000000120054cd8 $20 : 000000012006f3a0 00000001200083ac 0000000120059fa0 000000012006f3a0 $24 : 00000000000001c8 000000fff798f7d0 $28 : 000000fff79f75e0 000000ffffd23fe0 0000000120010000 0000000120015820 Hi : 00000000000001b6 Lo : 000000000001b0b9 epc : 000000fff798f7f4 0x000000fff798f7f4 ra : 0000000120015820 0x0000000120015820 Status: 00008cf3 KX SX UX USER EXL IE Cause : 00800020 (ExcCode 08) PrId : 000d0601 (Cavium Octeon+) 000000ffffc9b000-000000ffffcbc000 rwxp 000000fffffdf000 00:00 0 I get a lot of them from various programs running from rc scripts. It never manages to fully boot to login/shell. If I take the linux-4.12 arch/mips/include/asm/cmpxchg.h and drop that in place on a linux-4.13 (or even linux-4.14-rc3) I can compile and run everything successfully. Any thoughts? Regards Greg > --- > > arch/mips/include/asm/cmpxchg.h | 59 ++++++++++++++++++++++------------------- > 1 file changed, 32 insertions(+), 27 deletions(-) > > diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h > index e9c1e97bc29d..516cb66f066b 100644 > --- a/arch/mips/include/asm/cmpxchg.h > +++ b/arch/mips/include/asm/cmpxchg.h > @@ -34,7 +34,7 @@ > * > * - Get an error at link-time due to the call to the missing function. > */ > -extern void __cmpxchg_called_with_bad_pointer(void) > +extern unsigned long __cmpxchg_called_with_bad_pointer(void) > __compiletime_error("Bad argument size for cmpxchg"); > extern unsigned long __xchg_called_with_bad_pointer(void) > __compiletime_error("Bad argument size for xchg"); > @@ -137,38 +137,43 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz > __ret; \ > }) > > -#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier) \ > +static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, > + unsigned long new, unsigned int size) > +{ > + switch (size) { > + case 4: > + return __cmpxchg_asm("ll", "sc", (volatile u32 *)ptr, old, new); > + > + case 8: > + /* lld/scd are only available for MIPS64 */ > + if (!IS_ENABLED(CONFIG_64BIT)) > + return __cmpxchg_called_with_bad_pointer(); > + > + return __cmpxchg_asm("lld", "scd", (volatile u64 *)ptr, old, new); > + > + default: > + return __cmpxchg_called_with_bad_pointer(); > + } > +} > + > +#define cmpxchg_local(ptr, old, new) \ > + ((__typeof__(*(ptr))) \ > + __cmpxchg((ptr), \ > + (unsigned long)(__typeof__(*(ptr)))(old), \ > + (unsigned long)(__typeof__(*(ptr)))(new), \ > + sizeof(*(ptr)))) > + > +#define cmpxchg(ptr, old, new) \ > ({ \ > - __typeof__(ptr) __ptr = (ptr); \ > - __typeof__(*(ptr)) __old = (old); \ > - __typeof__(*(ptr)) __new = (new); \ > - __typeof__(*(ptr)) __res = 0; \ > - \ > - pre_barrier; \ > - \ > - switch (sizeof(*(__ptr))) { \ > - case 4: \ > - __res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new); \ > - break; \ > - case 8: \ > - if (sizeof(long) == 8) { \ > - __res = __cmpxchg_asm("lld", "scd", __ptr, \ > - __old, __new); \ > - break; \ > - } \ > - default: \ > - __cmpxchg_called_with_bad_pointer(); \ > - break; \ > - } \ > + __typeof__(*(ptr)) __res; \ > \ > - post_barrier; \ > + smp_mb__before_llsc(); \ > + __res = cmpxchg_local((ptr), (old), (new)); \ > + smp_llsc_mb(); \ > \ > __res; \ > }) > > -#define cmpxchg(ptr, old, new) __cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb()) > -#define cmpxchg_local(ptr, old, new) __cmpxchg(ptr, old, new, , ) > - > #ifdef CONFIG_64BIT > #define cmpxchg64_local(ptr, o, n) \ > ({ \ > -- > 2.13.1
