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s390/timex: fix get_tod_clock_ext() inline assembly

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For C language, it treats array parameter as a pointer, so sizeof for an
array parameter is equal to sizeof for a pointer, which causes compiler
warning (with allmodconfig by gcc 5):

  ./arch/s390/include/asm/timex.h: In function 'get_tod_clock_ext':
  ./arch/s390/include/asm/timex.h:76:32: warning: 'sizeof' on array function parameter 'clk' will return size of 'char *' [-Wsizeof-array-argument]
    typedef struct { char _[sizeof(clk)]; } addrtype;
                                  ^
Can use macro CLOCK_STORE_SIZE instead of all related hard code numbers,
which also can avoid this warning. And also add a tab to CLOCK_TICK_RATE
definition to match coding styles.

[heiko.carstens@de.ibm.com]:
Chen's patch actually fixes a bug within the get_tod_clock_ext() inline assembly
where we incorrectly tell the compiler that only 8 bytes of memory get changed
instead of 16 bytes.
This would allow gcc to generate incorrect code. Right now this doesn't seem to
be the case.
Also slightly changed the patch a bit.
- renamed CLOCK_STORE_SIZE to STORE_CLOCK_EXT_SIZE
- changed get_tod_clock_ext() to receive a char pointer parameter

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Chen Gang 2015-01-01 22:27:32 +08:00 committed by Martin Schwidefsky
parent 98590460d4
commit e38f978133
2 changed files with 7 additions and 5 deletions
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2
arch/s390/hypfs/hypfs_vm.c
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@ -231,7 +231,7 @@ failed:
struct dbfs_d2fc_hdr {
u64 len; /* Length of d2fc buffer without header */
u16 version; /* Version of header */
char tod_ext[16]; /* TOD clock for d2fc */
char tod_ext[STORE_CLOCK_EXT_SIZE]; /* TOD clock for d2fc */
u64 count; /* Number of VM guests in d2fc buffer */
char reserved[30];
} __attribute__ ((packed));

10
arch/s390/include/asm/timex.h
View File

@ -67,20 +67,22 @@ static inline void local_tick_enable(unsigned long long comp)
set_clock_comparator(S390_lowcore.clock_comparator);
}
#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
#define STORE_CLOCK_EXT_SIZE 16 /* stcke writes 16 bytes */
typedef unsigned long long cycles_t;
static inline void get_tod_clock_ext(char clk[16])
static inline void get_tod_clock_ext(char *clk)
{
typedef struct { char _[sizeof(clk)]; } addrtype;
typedef struct { char _[STORE_CLOCK_EXT_SIZE]; } addrtype;
asm volatile("stcke %0" : "=Q" (*(addrtype *) clk) : : "cc");
}
static inline unsigned long long get_tod_clock(void)
{
unsigned char clk[16];
unsigned char clk[STORE_CLOCK_EXT_SIZE];
get_tod_clock_ext(clk);
return *((unsigned long long *)&clk[1]);
}