@@ -39,6 +39,7 @@
#ifndef __ASSEMBLY__
#include <linux/unistd.h>
+#include <linux/time.h>
#define SYSCALL_MAP_SIZE ((__NR_syscalls + 31) / 32)
@@ -83,6 +84,7 @@ struct vdso_data {
__u32 icache_log_block_size; /* L1 i-cache log block size */
__s32 wtom_clock_sec; /* Wall to monotonic clock */
__s32 wtom_clock_nsec;
+ struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */
__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
};
@@ -102,6 +104,7 @@ struct vdso_data {
__u32 tz_dsttime; /* Type of dst correction 0x5C */
__s32 wtom_clock_sec; /* Wall to monotonic clock */
__s32 wtom_clock_nsec;
+ struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 dcache_block_size; /* L1 d-cache block size */
__u32 icache_block_size; /* L1 i-cache block size */
@@ -306,6 +306,7 @@ int main(void)
DEFINE(CFG_SYSCALL_MAP32, offsetof(struct vdso_data, syscall_map_32));
DEFINE(WTOM_CLOCK_SEC, offsetof(struct vdso_data, wtom_clock_sec));
DEFINE(WTOM_CLOCK_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
+ DEFINE(STAMP_XTIME, offsetof(struct vdso_data, stamp_xtime));
DEFINE(CFG_ICACHE_BLOCKSZ, offsetof(struct vdso_data, icache_block_size));
DEFINE(CFG_DCACHE_BLOCKSZ, offsetof(struct vdso_data, dcache_block_size));
DEFINE(CFG_ICACHE_LOGBLOCKSZ, offsetof(struct vdso_data, icache_log_block_size));
@@ -456,6 +456,7 @@ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
vdso_data->tb_to_xs = new_tb_to_xs;
vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
+ vdso_data->stamp_xtime = xtime;
smp_wmb();
++(vdso_data->tb_update_count);
}
@@ -16,6 +16,13 @@
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
+/* Offset for the low 32-bit part of a field of long type */
+#ifdef CONFIG_PPC64
+#define LOPART 4
+#else
+#define LOPART 0
+#endif
+
.text
/*
* Exact prototype of gettimeofday
@@ -90,101 +97,53 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
- mr r10,r3 /* r10 saves id */
mr r11,r4 /* r11 saves tp */
bl __get_datapage@local /* get data page */
mr r9,r3 /* datapage ptr in r9 */
- beq cr1,50f /* if monotonic -> jump there */
-
- /*
- * CLOCK_REALTIME
- */
-
- bl __do_get_xsec@local /* get xsec from tb & kernel */
- bne- 98f /* out of line -> do syscall */
-
- /* seconds are xsec >> 20 */
- rlwinm r5,r4,12,20,31
- rlwimi r5,r3,12,0,19
- stw r5,TSPC32_TV_SEC(r11)
- /* get remaining xsec and convert to nsec. we scale
- * up remaining xsec by 12 bits and get the top 32 bits
- * of the multiplication, then we multiply by 1000
- */
- rlwinm r5,r4,12,0,19
- lis r6,1000000@h
- ori r6,r6,1000000@l
- mulhwu r5,r5,r6
- mulli r5,r5,1000
- stw r5,TSPC32_TV_NSEC(r11)
- mtlr r12
- crclr cr0*4+so
- li r3,0
- blr
+50: bl __do_get_tspec@local /* get sec/nsec from tb & kernel */
+ bne cr1,80f /* not monotonic -> all done */
/*
* CLOCK_MONOTONIC
*/
-50: bl __do_get_xsec@local /* get xsec from tb & kernel */
- bne- 98f /* out of line -> do syscall */
-
- /* seconds are xsec >> 20 */
- rlwinm r6,r4,12,20,31
- rlwimi r6,r3,12,0,19
-
- /* get remaining xsec and convert to nsec. we scale
- * up remaining xsec by 12 bits and get the top 32 bits
- * of the multiplication, then we multiply by 1000
- */
- rlwinm r7,r4,12,0,19
- lis r5,1000000@h
- ori r5,r5,1000000@l
- mulhwu r7,r7,r5
- mulli r7,r7,1000
-
/* now we must fixup using wall to monotonic. We need to snapshot
* that value and do the counter trick again. Fortunately, we still
* have the counter value in r8 that was returned by __do_get_xsec.
- * At this point, r6,r7 contain our sec/nsec values, r3,r4 and r5
- * can be used
+ * At this point, r3,r4 contain our sec/nsec values, r5 and r6
+ * can be used, r7 contains NSEC_PER_SEC.
*/
- lwz r3,WTOM_CLOCK_SEC(r9)
- lwz r4,WTOM_CLOCK_NSEC(r9)
+ lwz r5,WTOM_CLOCK_SEC(r9)
+ lwz r6,WTOM_CLOCK_NSEC(r9)
- /* We now have our result in r3,r4. We create a fake dependency
- * on that result and re-check the counter
+ /* We now have our offset in r5,r6. We create a fake dependency
+ * on that value and re-check the counter
*/
- or r5,r4,r3
- xor r0,r5,r5
+ or r0,r6,r5
+ xor r0,r0,r0
add r9,r9,r0
-#ifdef CONFIG_PPC64
- lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
-#else
- lwz r0,(CFG_TB_UPDATE_COUNT)(r9)
-#endif
+ lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
cmpl cr0,r8,r0 /* check if updated */
bne- 50b
- /* Calculate and store result. Note that this mimmics the C code,
+ /* Calculate and store result. Note that this mimics the C code,
* which may cause funny results if nsec goes negative... is that
* possible at all ?
*/
- add r3,r3,r6
- add r4,r4,r7
- lis r5,NSEC_PER_SEC@h
- ori r5,r5,NSEC_PER_SEC@l
- cmpl cr0,r4,r5
- cmpli cr1,r4,0
+ add r3,r3,r5
+ add r4,r4,r6
+ cmpw cr0,r4,r7
+ cmpwi cr1,r4,0
blt 1f
- subf r4,r5,r4
+ subf r4,r7,r4
addi r3,r3,1
-1: bge cr1,1f
+1: bge cr1,80f
addi r3,r3,-1
- add r4,r4,r5
-1: stw r3,TSPC32_TV_SEC(r11)
+ add r4,r4,r7
+
+80: stw r3,TSPC32_TV_SEC(r11)
stw r4,TSPC32_TV_NSEC(r11)
mtlr r12
@@ -195,10 +154,6 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
/*
* syscall fallback
*/
-98:
- mtlr r12
- mr r3,r10
- mr r4,r11
99:
li r0,__NR_clock_gettime
sc
@@ -254,11 +209,7 @@ __do_get_xsec:
/* Check for update count & load values. We use the low
* order 32 bits of the update count
*/
-#ifdef CONFIG_PPC64
-1: lwz r8,(CFG_TB_UPDATE_COUNT+4)(r9)
-#else
-1: lwz r8,(CFG_TB_UPDATE_COUNT)(r9)
-#endif
+1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
andi. r0,r8,1 /* pending update ? loop */
bne- 1b
xor r0,r8,r8 /* create dependency */
@@ -305,11 +256,7 @@ __do_get_xsec:
or r6,r4,r3
xor r0,r6,r6
add r9,r9,r0
-#ifdef CONFIG_PPC64
- lwz r0,(CFG_TB_UPDATE_COUNT+4)(r9)
-#else
- lwz r0,(CFG_TB_UPDATE_COUNT)(r9)
-#endif
+ lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
cmpl cr0,r8,r0 /* check if updated */
bne- 1b
@@ -322,3 +269,98 @@ __do_get_xsec:
*/
3: blr
.cfi_endproc
+
+/*
+ * This is the core of clock_gettime(), it returns the current
+ * time in seconds and nanoseconds in r3 and r4.
+ * It expects the datapage ptr in r9 and doesn't clobber it.
+ * It clobbers r0, r5, r6, r10 and returns NSEC_PER_SEC in r7.
+ * On return, r8 contains the counter value that can be reused.
+ * This clobbers cr0 but not any other cr field.
+ */
+__do_get_tspec:
+ .cfi_startproc
+ /* Check for update count & load values. We use the low
+ * order 32 bits of the update count
+ */
+1: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
+ andi. r0,r8,1 /* pending update ? loop */
+ bne- 1b
+ xor r0,r8,r8 /* create dependency */
+ add r9,r9,r0
+
+ /* Load orig stamp (offset to TB) */
+ lwz r5,CFG_TB_ORIG_STAMP(r9)
+ lwz r6,(CFG_TB_ORIG_STAMP+4)(r9)
+
+ /* Get a stable TB value */
+2: mftbu r3
+ mftbl r4
+ mftbu r0
+ cmpl cr0,r3,r0
+ bne- 2b
+
+ /* Subtract tb orig stamp and shift left 12 bits.
+ */
+ subfc r7,r6,r4
+ subfe r0,r5,r3
+ slwi r0,r0,12
+ rlwimi. r0,r7,12,20,31
+ slwi r7,r7,12
+
+ /* Load scale factor & do multiplication */
+ lwz r5,CFG_TB_TO_XS(r9) /* load values */
+ lwz r6,(CFG_TB_TO_XS+4)(r9)
+ mulhwu r3,r7,r6
+ mullw r10,r7,r5
+ mulhwu r4,r7,r5
+ addc r10,r3,r10
+ li r3,0
+
+ beq+ 4f /* skip high part computation if 0 */
+ mulhwu r3,r0,r5
+ mullw r7,r0,r5
+ mulhwu r5,r0,r6
+ mullw r6,r0,r6
+ adde r4,r4,r7
+ addze r3,r3
+ addc r4,r4,r5
+ addze r3,r3
+ addc r10,r10,r6
+
+4: addze r4,r4 /* add in carry */
+ lis r7,NSEC_PER_SEC@h
+ ori r7,r7,NSEC_PER_SEC@l
+ mulhwu r4,r4,r7 /* convert to nanoseconds */
+
+ /* At this point, we have seconds & nanoseconds since the xtime
+ * stamp in r3+CA and r4. Load & add the xtime stamp.
+ */
+#ifdef CONFIG_PPC64
+ lwz r5,STAMP_XTIME+TSPC64_TV_SEC+LOPART(r9)
+ lwz r6,STAMP_XTIME+TSPC64_TV_NSEC+LOPART(r9)
+#else
+ lwz r5,STAMP_XTIME+TSPC32_TV_SEC(r9)
+ lwz r6,STAMP_XTIME+TSPC32_TV_NSEC(r9)
+#endif
+ add r4,r4,r6
+ adde r3,r3,r5
+
+ /* We now have our result in r3,r4. We create a fake dependency
+ * on that result and re-check the counter
+ */
+ or r6,r4,r3
+ xor r0,r6,r6
+ add r9,r9,r0
+ lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
+ cmpl cr0,r8,r0 /* check if updated */
+ bne- 1b
+
+ /* check for nanosecond overflow and adjust if necessary */
+ cmpw r4,r7
+ bltlr /* all done if no overflow */
+ subf r4,r7,r4 /* adjust if overflow */
+ addi r3,r3,1
+
+ blr
+ .cfi_endproc
@@ -75,90 +75,49 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
mflr r12 /* r12 saves lr */
.cfi_register lr,r12
- mr r10,r3 /* r10 saves id */
mr r11,r4 /* r11 saves tp */
bl V_LOCAL_FUNC(__get_datapage) /* get data page */
- beq cr1,50f /* if monotonic -> jump there */
-
- /*
- * CLOCK_REALTIME
- */
-
- bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
-
- lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
- ori r7,r7,16960
- rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
- rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
- std r5,TSPC64_TV_SEC(r11) /* store sec in tv */
- subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
- mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) /
- * XSEC_PER_SEC
- */
- rldicl r0,r0,44,20
- mulli r0,r0,1000 /* nsec = usec * 1000 */
- std r0,TSPC64_TV_NSEC(r11) /* store nsec in tp */
-
- mtlr r12
- crclr cr0*4+so
- li r3,0
- blr
+50: bl V_LOCAL_FUNC(__do_get_tspec) /* get time from tb & kernel */
+ bne cr1,80f /* if not monotonic, all done */
/*
* CLOCK_MONOTONIC
*/
-50: bl V_LOCAL_FUNC(__do_get_xsec) /* get xsec from tb & kernel */
-
- lis r7,15 /* r7 = 1000000 = USEC_PER_SEC */
- ori r7,r7,16960
- rldicl r5,r4,44,20 /* r5 = sec = xsec / XSEC_PER_SEC */
- rldicr r6,r5,20,43 /* r6 = sec * XSEC_PER_SEC */
- subf r0,r6,r4 /* r0 = xsec = (xsec - r6) */
- mulld r0,r0,r7 /* usec = (xsec * USEC_PER_SEC) /
- * XSEC_PER_SEC
- */
- rldicl r6,r0,44,20
- mulli r6,r6,1000 /* nsec = usec * 1000 */
-
/* now we must fixup using wall to monotonic. We need to snapshot
* that value and do the counter trick again. Fortunately, we still
- * have the counter value in r8 that was returned by __do_get_xsec.
- * At this point, r5,r6 contain our sec/nsec values.
- * can be used
+ * have the counter value in r8 that was returned by __do_get_tspec.
+ * At this point, r4,r5 contain our sec/nsec values.
*/
- lwa r4,WTOM_CLOCK_SEC(r3)
- lwa r7,WTOM_CLOCK_NSEC(r3)
+ lwa r6,WTOM_CLOCK_SEC(r3)
+ lwa r9,WTOM_CLOCK_NSEC(r3)
- /* We now have our result in r4,r7. We create a fake dependency
+ /* We now have our result in r6,r9. We create a fake dependency
* on that result and re-check the counter
*/
- or r9,r4,r7
- xor r0,r9,r9
+ or r0,r6,r9
+ xor r0,r0,r0
add r3,r3,r0
ld r0,CFG_TB_UPDATE_COUNT(r3)
cmpld cr0,r0,r8 /* check if updated */
bne- 50b
- /* Calculate and store result. Note that this mimmics the C code,
- * which may cause funny results if nsec goes negative... is that
- * possible at all ?
+ /* Add wall->monotonic offset and check for overflow or underflow.
*/
- add r4,r4,r5
- add r7,r7,r6
- lis r9,NSEC_PER_SEC@h
- ori r9,r9,NSEC_PER_SEC@l
- cmpl cr0,r7,r9
- cmpli cr1,r7,0
+ add r4,r4,r6
+ add r5,r5,r9
+ cmpd cr0,r5,r7
+ cmpdi cr1,r5,0
blt 1f
- subf r7,r9,r7
+ subf r5,r7,r5
addi r4,r4,1
-1: bge cr1,1f
+1: bge cr1,80f
addi r4,r4,-1
- add r7,r7,r9
-1: std r4,TSPC64_TV_SEC(r11)
- std r7,TSPC64_TV_NSEC(r11)
+ add r5,r5,r7
+
+80: std r4,TSPC64_TV_SEC(r11)
+ std r5,TSPC64_TV_NSEC(r11)
mtlr r12
crclr cr0*4+so
@@ -168,10 +127,6 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime)
/*
* syscall fallback
*/
-98:
- mtlr r12
- mr r3,r10
- mr r4,r11
99:
li r0,__NR_clock_gettime
sc
@@ -253,3 +208,59 @@ V_FUNCTION_BEGIN(__do_get_xsec)
blr
.cfi_endproc
V_FUNCTION_END(__do_get_xsec)
+
+/*
+ * This is the core of clock_gettime(), it returns the current
+ * time in seconds and nanoseconds in r4 and r5.
+ * It expects the datapage ptr in r3 and doesn't clobber it.
+ * It clobbers r0 and r6 and returns NSEC_PER_SEC in r7.
+ * On return, r8 contains the counter value that can be reused.
+ * This clobbers cr0 but not any other cr field.
+ */
+V_FUNCTION_BEGIN(__do_get_tspec)
+ .cfi_startproc
+ /* check for update count & load values */
+1: ld r8,CFG_TB_UPDATE_COUNT(r3)
+ andi. r0,r8,1 /* pending update ? loop */
+ bne- 1b
+ xor r0,r8,r8 /* create dependency */
+ add r3,r3,r0
+
+ /* Get TB & offset it. We use the MFTB macro which will generate
+ * workaround code for Cell.
+ */
+ MFTB(r7)
+ ld r9,CFG_TB_ORIG_STAMP(r3)
+ subf r7,r9,r7
+
+ /* Scale result */
+ ld r5,CFG_TB_TO_XS(r3)
+ sldi r7,r7,12 /* compute time since stamp_xtime */
+ mulhdu r6,r7,r5 /* in units of 2^-32 seconds */
+
+ /* Add stamp since epoch */
+ ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3)
+ ld r5,STAMP_XTIME+TSPC64_TV_NSEC(r3)
+ or r0,r4,r5
+ or r0,r0,r6
+ xor r0,r0,r0
+ add r3,r3,r0
+ ld r0,CFG_TB_UPDATE_COUNT(r3)
+ cmpld r0,r8 /* check if updated */
+ bne- 1b /* reload if so */
+
+ /* convert to seconds & nanoseconds and add to stamp */
+ lis r7,NSEC_PER_SEC@h
+ ori r7,r7,NSEC_PER_SEC@l
+ mulhwu r0,r6,r7 /* compute nanoseconds and */
+ srdi r6,r6,32 /* seconds since stamp_xtime */
+ clrldi r0,r0,32
+ add r5,r5,r0 /* add nanoseconds together */
+ cmpd r5,r7 /* overflow? */
+ add r4,r4,r6
+ bltlr /* all done if no overflow */
+ subf r5,r7,r5 /* if overflow, adjust */
+ addi r4,r4,1
+ blr
+ .cfi_endproc
+V_FUNCTION_END(__do_get_tspec)
Currently the clock_gettime implementation in the VDSO produces a result with microsecond resolution for the cases that are handled without a system call, i.e. CLOCK_REALTIME and CLOCK_MONOTONIC. The nanoseconds field of the result is obtained by computing a microseconds value and multiplying by 1000. This changes the code in the VDSO to do the computation for clock_gettime with nanosecond resolution. That means that the resolution of the result will ultimately depend on the timebase frequency. Because the timestamp in the VDSO datapage (stamp_xsec, the real time corresponding to the timebase count in tb_orig_stamp) is in units of 2^-20 seconds, it doesn't have sufficient resolution for computing a result with nanosecond resolution. Therefore this adds a copy of xtime to the VDSO datapage and updates it in update_gtod() along with the other time-related fields. Signed-off-by: Paul Mackerras <paulus@samba.org> ---