From 11a247e376669323b0d9f56fbdb5c163c6310112 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Tue, 29 Nov 2016 13:52:01 +0100 Subject: [PATCH] s390: Remove VLAIS in ptff() and clear_table() The ptff() and clear_table() functions use the gcc extension "variable length arrays in structures" (VLAIS) to define in the inline assembler constraints the area of the clobbered memory. This extension will most likely never be supported by LLVM/Clang. Since currently BPF programs are compiled with LLVM, this leads to the following compile errors: $ cd samples/bpf $ make In file included from /root/linux-master/samples/bpf/tracex1_kern.c:8: In file included from ./include/linux/netdevice.h:44: ... In file included from ./arch/s390/include/asm/mmu_context.h:10: ./arch/s390/include/asm/pgalloc.h:30:24: error: fields must have a constant size: 'variable length array in structure' extension will never be supported typedef struct { char _[n]; } addrtype; In file included from /root/linux-master/samples/bpf/tracex1_kern.c:7: In file included from ./include/linux/skbuff.h:18: ... In file included from ./include/linux/jiffies.h:8: In file included from ./include/linux/timex.h:65: ./arch/s390/include/asm/timex.h:105:24: error: fields must have a constant size: 'variable length array in structure' extension will never be supported typedef struct { char _[len]; } addrtype; To fix this do the following: - Convert ptff() into a macro that then uses a fixed size array when expanded. - Convert the clear_table() function and use an inline assembly with fixed size array in a loop. The runtime performance of the new version is even better than the old version (tested with EC12/z13 and gcc 4.8.5/6.2.1 with "-march=z196 -O2"). Reported-by: Zvonko Kosic Signed-off-by: Michael Holzheu Acked-by: Martin Schwidefsky Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/pgalloc.h | 22 ++++++++++---------- arch/s390/include/asm/timex.h | 37 ++++++++++++++++++++------------- 2 files changed, 33 insertions(+), 26 deletions(-) diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h index f4eb9843eed4..166f703dad7c 100644 --- a/arch/s390/include/asm/pgalloc.h +++ b/arch/s390/include/asm/pgalloc.h @@ -27,17 +27,17 @@ extern int page_table_allocate_pgste; static inline void clear_table(unsigned long *s, unsigned long val, size_t n) { - typedef struct { char _[n]; } addrtype; - - *s = val; - n = (n / 256) - 1; - asm volatile( - " mvc 8(248,%0),0(%0)\n" - "0: mvc 256(256,%0),0(%0)\n" - " la %0,256(%0)\n" - " brct %1,0b\n" - : "+a" (s), "+d" (n), "=m" (*(addrtype *) s) - : "m" (*(addrtype *) s)); + struct addrtype { char _[256]; }; + int i; + + for (i = 0; i < n; i += 256) { + *s = val; + asm volatile( + "mvc 8(248,%[s]),0(%[s])\n" + : "+m" (*(struct addrtype *) s) + : [s] "a" (s)); + s += 256 / sizeof(long); + } } static inline void crst_table_init(unsigned long *crst, unsigned long entry) diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index b62d8c4ec022..de8298800722 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -98,21 +98,28 @@ struct ptff_qui { unsigned int pad_0x5c[41]; } __packed; -static inline int ptff(void *ptff_block, size_t len, unsigned int func) -{ - typedef struct { char _[len]; } addrtype; - register unsigned int reg0 asm("0") = func; - register unsigned long reg1 asm("1") = (unsigned long) ptff_block; - int rc; - - asm volatile( - " .word 0x0104\n" - " ipm %0\n" - " srl %0,28\n" - : "=d" (rc), "+m" (*(addrtype *) ptff_block) - : "d" (reg0), "d" (reg1) : "cc"); - return rc; -} +/* + * ptff - Perform timing facility function + * @ptff_block: Pointer to ptff parameter block + * @len: Length of parameter block + * @func: Function code + * Returns: Condition code (0 on success) + */ +#define ptff(ptff_block, len, func) \ +({ \ + struct addrtype { char _[len]; }; \ + register unsigned int reg0 asm("0") = func; \ + register unsigned long reg1 asm("1") = (unsigned long) (ptff_block);\ + int rc; \ + \ + asm volatile( \ + " .word 0x0104\n" \ + " ipm %0\n" \ + " srl %0,28\n" \ + : "=d" (rc), "+m" (*(struct addrtype *) reg1) \ + : "d" (reg0), "d" (reg1) : "cc"); \ + rc; \ +}) static inline unsigned long long local_tick_disable(void) { -- 2.20.1