sparc: Fix VDSO build with older binutils.

Older versions of bintutils do not allow symbol math across different
segments on sparc:

====================
Assembler messages:
99: Error: operation combines symbols in different segments
====================

This is controlled by whether or not DIFF_EXPR_OK is defined in
gas/config/tc-*.h and for sparc this was not the case until mid-2017.

So we have to patch between %stick and %tick another way.

Do what powerpc does and emit two versions of the relevant functions,
one using %tick and one using %stick, and patch the symbols in the
dynamic symbol table.

Fixes: 2f6c9bf31a ("sparc: Improve VDSO instruction patching.")
Reported-by: Meelis Roos <mroos@linux.ee>
Tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/vdso/vclock_gettime.c

@@ -90,16 +90,15 @@ notrace static __always_inline u64 vread_tick(void)
 {
 	u64	ret;
 
-	__asm__ __volatile__("1:\n\t"
-			     "rd		%%tick, %0\n\t"
-			     ".pushsection	.tick_patch, \"a\"\n\t"
-			     ".word		1b - ., 1f - .\n\t"
-			     ".popsection\n\t"
-			     ".pushsection	.tick_patch_replacement, \"ax\"\n\t"
-			     "1:\n\t"
-			     "rd		%%asr24, %0\n\t"
-			     ".popsection\n"
-			     : "=r" (ret));
+	__asm__ __volatile__("rd %%tick, %0" : "=r" (ret));
+	return ret;
+}
+
+notrace static __always_inline u64 vread_tick_stick(void)
+{
+	u64	ret;
+
+	__asm__ __volatile__("rd %%asr24, %0" : "=r" (ret));
 	return ret;
 }
 #else
@@ -107,16 +106,18 @@ notrace static __always_inline u64 vread_tick(void)
 {
 	register unsigned long long ret asm("o4");
 
-	__asm__ __volatile__("1:\n\t"
-			     "rd		%%tick, %L0\n\t"
-			     "srlx		%L0, 32, %H0\n\t"
-			     ".pushsection	.tick_patch, \"a\"\n\t"
-			     ".word		1b - ., 1f - .\n\t"
-			     ".popsection\n\t"
-			     ".pushsection	.tick_patch_replacement, \"ax\"\n\t"
-			     "1:\n\t"
-			     "rd		%%asr24, %L0\n\t"
-			     ".popsection\n"
+	__asm__ __volatile__("rd %%tick, %L0\n\t"
+			     "srlx %L0, 32, %H0"
+			     : "=r" (ret));
+	return ret;
+}
+
+notrace static __always_inline u64 vread_tick_stick(void)
+{
+	register unsigned long long ret asm("o4");
+
+	__asm__ __volatile__("rd %%asr24, %L0\n\t"
+			     "srlx %L0, 32, %H0"
 			     : "=r" (ret));
 	return ret;
 }
@@ -132,6 +133,16 @@ notrace static __always_inline u64 vgetsns(struct vvar_data *vvar)
 	return v * vvar->clock.mult;
 }
 
+notrace static __always_inline u64 vgetsns_stick(struct vvar_data *vvar)
+{
+	u64 v;
+	u64 cycles;
+
+	cycles = vread_tick_stick();
+	v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
+	return v * vvar->clock.mult;
+}
+
 notrace static __always_inline int do_realtime(struct vvar_data *vvar,
 					       struct timespec *ts)
 {
@@ -152,6 +163,26 @@ notrace static __always_inline int do_realtime(struct vvar_data *vvar,
 	return 0;
 }
 
+notrace static __always_inline int do_realtime_stick(struct vvar_data *vvar,
+						     struct timespec *ts)
+{
+	unsigned long seq;
+	u64 ns;
+
+	do {
+		seq = vvar_read_begin(vvar);
+		ts->tv_sec = vvar->wall_time_sec;
+		ns = vvar->wall_time_snsec;
+		ns += vgetsns_stick(vvar);
+		ns >>= vvar->clock.shift;
+	} while (unlikely(vvar_read_retry(vvar, seq)));
+
+	ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+
+	return 0;
+}
+
 notrace static __always_inline int do_monotonic(struct vvar_data *vvar,
 						struct timespec *ts)
 {
@@ -172,6 +203,26 @@ notrace static __always_inline int do_monotonic(struct vvar_data *vvar,
 	return 0;
 }
 
+notrace static __always_inline int do_monotonic_stick(struct vvar_data *vvar,
+						      struct timespec *ts)
+{
+	unsigned long seq;
+	u64 ns;
+
+	do {
+		seq = vvar_read_begin(vvar);
+		ts->tv_sec = vvar->monotonic_time_sec;
+		ns = vvar->monotonic_time_snsec;
+		ns += vgetsns_stick(vvar);
+		ns >>= vvar->clock.shift;
+	} while (unlikely(vvar_read_retry(vvar, seq)));
+
+	ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+
+	return 0;
+}
+
 notrace static int do_realtime_coarse(struct vvar_data *vvar,
 				      struct timespec *ts)
 {
@@ -227,6 +278,31 @@ int
 clock_gettime(clockid_t, struct timespec *)
 	__attribute__((weak, alias("__vdso_clock_gettime")));
 
+notrace int
+__vdso_clock_gettime_stick(clockid_t clock, struct timespec *ts)
+{
+	struct vvar_data *vvd = get_vvar_data();
+
+	switch (clock) {
+	case CLOCK_REALTIME:
+		if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
+			break;
+		return do_realtime_stick(vvd, ts);
+	case CLOCK_MONOTONIC:
+		if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
+			break;
+		return do_monotonic_stick(vvd, ts);
+	case CLOCK_REALTIME_COARSE:
+		return do_realtime_coarse(vvd, ts);
+	case CLOCK_MONOTONIC_COARSE:
+		return do_monotonic_coarse(vvd, ts);
+	}
+	/*
+	 * Unknown clock ID ? Fall back to the syscall.
+	 */
+	return vdso_fallback_gettime(clock, ts);
+}
+
 notrace int
 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 {
@@ -262,3 +338,36 @@ __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 int
 gettimeofday(struct timeval *, struct timezone *)
 	__attribute__((weak, alias("__vdso_gettimeofday")));
+
+notrace int
+__vdso_gettimeofday_stick(struct timeval *tv, struct timezone *tz)
+{
+	struct vvar_data *vvd = get_vvar_data();
+
+	if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
+		if (likely(tv != NULL)) {
+			union tstv_t {
+				struct timespec ts;
+				struct timeval tv;
+			} *tstv = (union tstv_t *) tv;
+			do_realtime_stick(vvd, &tstv->ts);
+			/*
+			 * Assign before dividing to ensure that the division is
+			 * done in the type of tv_usec, not tv_nsec.
+			 *
+			 * There cannot be > 1 billion usec in a second:
+			 * do_realtime() has already distributed such overflow
+			 * into tv_sec.  So we can assign it to an int safely.
+			 */
+			tstv->tv.tv_usec = tstv->ts.tv_nsec;
+			tstv->tv.tv_usec /= 1000;
+		}
+		if (unlikely(tz != NULL)) {
+			/* Avoid memcpy. Some old compilers fail to inline it */
+			tz->tz_minuteswest = vvd->tz_minuteswest;
+			tz->tz_dsttime = vvd->tz_dsttime;
+		}
+		return 0;
+	}
+	return vdso_fallback_gettimeofday(tv, tz);
+}