Aaron Durbin (adurbin@google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/5411
-gerrit
commit 777fbfa22342d76b0ca2eaed6f275fa8a6672151 Author: Aaron Durbin adurbin@chromium.org Date: Fri Mar 28 08:40:59 2014 -0500
x86: use car_(get|set)_var accessors for apic timer
The timer_fsb variable was not correctly being accessed in the presence of cache-as-ram. The cache-as-ram backing store could be torn down but then udelay() could be called causing hangs from accessing variables that have unknown values.
Instead change the timer_fsb variable to g_timer_fsb and obtain the value through a local access method that does the correct things to obtain the correct value.
Change-Id: Ia3e30808498cbe4a7f6f116c17a8cf1240a807a3 Signed-off-by: Aaron Durbin adurbin@chromium.org --- src/cpu/x86/lapic/apic_timer.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/src/cpu/x86/lapic/apic_timer.c b/src/cpu/x86/lapic/apic_timer.c index 868fb92..a113143 100644 --- a/src/cpu/x86/lapic/apic_timer.c +++ b/src/cpu/x86/lapic/apic_timer.c @@ -34,14 +34,17 @@ */
#if CONFIG_UDELAY_LAPIC_FIXED_FSB -static const u32 timer_fsb = CONFIG_UDELAY_LAPIC_FIXED_FSB; +static inline u32 get_timer_fsb(void) +{ + return CONFIG_UDELAY_LAPIC_FIXED_FSB; +}
static int set_timer_fsb(void) { return 0; } #else -static u32 timer_fsb CAR_GLOBAL = 0; +static u32 g_timer_fsb CAR_GLOBAL;
static int set_timer_fsb(void) { @@ -56,25 +59,30 @@ static int set_timer_fsb(void) switch (c.x86_model) { case 0xe: /* Core Solo/Duo */ case 0x1c: /* Atom */ - timer_fsb = core_fsb[rdmsr(MSR_FSB_FREQ).lo & 7]; + car_set_var(g_timer_fsb, core_fsb[rdmsr(MSR_FSB_FREQ).lo & 7]); break; case 0xf: /* Core 2 or Xeon */ case 0x17: /* Enhanced Core */ - timer_fsb = core2_fsb[rdmsr(MSR_FSB_FREQ).lo & 7]; + car_set_var(g_timer_fsb, core2_fsb[rdmsr(MSR_FSB_FREQ).lo & 7]); break; case 0x2a: /* SandyBridge BCLK fixed at 100MHz*/ case 0x3a: /* IvyBridge BCLK fixed at 100MHz*/ case 0x3c: /* Haswell BCLK fixed at 100MHz */ case 0x45: /* Haswell-ULT BCLK fixed at 100MHz */ - timer_fsb = 100; + car_set_var(g_timer_fsb, 100); break; default: - timer_fsb = 200; + car_set_var(g_timer_fsb, 200); break; }
return 0; } + +static inline u32 get_timer_fsb(void) +{ + return car_get_var(g_timer_fsb); +} #endif
void init_timer(void) @@ -94,15 +102,18 @@ void init_timer(void)
void udelay(u32 usecs) { - u32 start, value, ticks; + u32 start, value, ticks, timer_fsb;
if (!thread_yield_microseconds(usecs)) return;
+ timer_fsb = get_timer_fsb(); if (!timer_fsb || (lapic_read(LAPIC_LVTT) & (LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED)) != - (LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED)) + (LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED)) { init_timer(); + timer_fsb = get_timer_fsb(); + }
/* Calculate the number of ticks to run, our FSB runs at timer_fsb Mhz */ ticks = usecs * timer_fsb; @@ -125,9 +136,11 @@ void timer_monotonic_get(struct mono_time *mt) { uint32_t current_tick; uint32_t usecs_elapsed; + uint32_t timer_fsb;
if (!mono_counter.initialized) { init_timer(); + timer_fsb = get_timer_fsb(); /* An FSB frequency of 200Mhz provides a 20 second polling * interval between timer_monotonic_get() calls before wrap * around occurs. */ @@ -139,6 +152,7 @@ void timer_monotonic_get(struct mono_time *mt) mono_counter.initialized = 1; }
+ timer_fsb = get_timer_fsb(); current_tick = lapic_read(LAPIC_TMCCT); /* Note that the APIC timer counts down. */ usecs_elapsed = (mono_counter.last_value - current_tick) / timer_fsb;