Re: [PATCHv6 22/36] x86/vdso: Add offsets page in vvar

---
 arch/Kconfig                          |  5 +++
 arch/x86/Kconfig                      |  1 +
 arch/x86/entry/vdso/vdso-layout.lds.S |  9 ++++-
 arch/x86/entry/vdso/vdso2c.c          |  3 ++
 arch/x86/entry/vdso/vma.c             | 12 +++++++
 arch/x86/include/asm/vdso.h           |  1 +
 init/Kconfig                          |  1 +
 lib/vdso/gettimeofday.c               | 47 +++++++++++++++++++++++++++

+extern u8 timens_page
+	__attribute__((visibility("hidden")));
+
+notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts)

+{
+	struct timens_offsets *timens = (struct timens_offsets *) &timens_page;
+	struct timespec64 *offset64;
+
+	switch (clk) {
+	case CLOCK_MONOTONIC:
+	case CLOCK_MONOTONIC_COARSE:
+	case CLOCK_MONOTONIC_RAW:
+		offset64 = &timens->monotonic;
+		break;
+	case CLOCK_BOOTTIME:
+		offset64 = &timens->boottime;
+		break;
+	default:
+		return;
+	}
+
+	/*
+	 * The kernel allows to set a negative offset only if the current clock
+	 * value in a namespace is positive, so the result tv_sec can't be
+	 * negative here.
+	 */
+	ts->tv_nsec += offset64->tv_nsec;
+	ts->tv_sec += offset64->tv_sec;
+	if (ts->tv_nsec >= NSEC_PER_SEC) {
+		ts->tv_nsec -= NSEC_PER_SEC;
+		ts->tv_sec++;
+	}
+	if (ts->tv_nsec < 0) {
+		ts->tv_nsec += NSEC_PER_SEC;
+		ts->tv_sec--;
+	}

+}
+#else
+notrace static __always_inline void clk_to_ns(clockid_t clk, struct __kernel_timespec *ts) {}
+#endif
+
 static int do_hres(const struct vdso_data *vd, clockid_t clk,
 		   struct __kernel_timespec *ts)
 {

@@ -65,6 +108,8 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 	ts->tv_nsec = ns;
 
+	clk_to_ns(clk, ts);
+
 	return 0;
 }
 

@@ -79,6 +124,8 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	clk_to_ns(clk, ts);
 }
 
 static __maybe_unused int

-- 
2.22.0