[1/6,SRU,Zesty] Revert "UBUNTU: SAUCE: arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled"

Message ID 20170830174128.32541-2-dann.frazier@canonical.com
State New
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Series
  • [1/6,SRU,Zesty] Revert "UBUNTU: SAUCE: arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled"
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Commit Message

dann frazier Aug. 30, 2017, 5:41 p.m.
BugLink: https://bugs.launchpad.net/bugs/1713821

This reverts commit 83f3444f36eba82cca61715f793d1f6411b06e3b.

Before this patch landed upstream, a fix was added to prevent CNTVCT_EL0
accesses from going untrapped if it was reset the the user access bit set:

  https://www.spinics.net/lists/arm-kernel/msg574175.html

Let's inherit this fix by replacing with the upstream version.

Signed-off-by: dann frazier <dann.frazier@canonical.com>
---
 drivers/clocksource/arm_arch_timer.c | 42 +++++++++++-------------------------
 1 file changed, 12 insertions(+), 30 deletions(-)

Patch

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 168421d2043f..18a8e5727ce7 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -74,7 +74,6 @@  static enum arch_timer_ppi_nr arch_timer_uses_ppi = ARCH_TIMER_VIRT_PPI;
 static bool arch_timer_c3stop;
 static bool arch_timer_mem_use_virtual;
 static bool arch_counter_suspend_stop;
-static bool vdso_default = true;
 
 static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
 
@@ -462,17 +461,6 @@  void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
 	}
 
 	static_branch_enable(&arch_timer_read_ool_enabled);
-
-	/*
-	 * Don't use the vdso fastpath if errata require using the
-	 * out-of-line counter accessor. We may change our mind pretty
-	 * late in the game (with a per-CPU erratum, for example), so
-	 * change both the default value and the vdso itself.
-	 */
-	if (wa->read_cntvct_el0) {
-		clocksource_counter.archdata.vdso_direct = false;
-		vdso_default = false;
-	}
 }
 
 static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type type,
@@ -539,19 +527,11 @@  static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t
 	__val;								\
 })
 
-static bool arch_timer_this_cpu_has_cntvct_wa(void)
-{
-	const struct arch_timer_erratum_workaround *wa;
-
-	wa = __this_cpu_read(timer_unstable_counter_workaround);
-	return wa && wa->read_cntvct_el0;
-}
 #else
 #define arch_timer_check_ool_workaround(t,a)		do { } while(0)
 #define erratum_set_next_event_tval_virt(...)		({BUG(); 0;})
 #define erratum_set_next_event_tval_phys(...)		({BUG(); 0;})
 #define erratum_handler(fn, r, ...)			({false;})
-#define arch_timer_this_cpu_has_cntvct_wa()		({false;})
 #endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
 
 static __always_inline irqreturn_t timer_handler(const int access,
@@ -771,15 +751,8 @@  static void arch_counter_set_user_access(void)
 			| ARCH_TIMER_VIRT_EVT_EN
 			| ARCH_TIMER_USR_PCT_ACCESS_EN);
 
-	/*
-	 * Enable user access to the virtual counter if it doesn't
-	 * need to be workaround. The vdso may have been already
-	 * disabled though.
-	 */
-	if (arch_timer_this_cpu_has_cntvct_wa())
-		pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id());
-	else
-		cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
+	/* Enable user access to the virtual counter */
+	cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
 
 	arch_timer_set_cntkctl(cntkctl);
 }
@@ -900,7 +873,16 @@  static void __init arch_counter_register(unsigned type)
 		else
 			arch_timer_read_counter = arch_counter_get_cntpct;
 
-		clocksource_counter.archdata.vdso_direct = vdso_default;
+		clocksource_counter.archdata.vdso_direct = true;
+
+#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
+		/*
+		 * Don't use the vdso fastpath if errata require using
+		 * the out-of-line counter accessor.
+		 */
+		if (static_branch_unlikely(&arch_timer_read_ool_enabled))
+			clocksource_counter.archdata.vdso_direct = false;
+#endif
 	} else {
 		arch_timer_read_counter = arch_counter_get_cntvct_mem;
 	}