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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] x86: Adjust rdtsc inline assembly
Currently there are three related rdtsc macros, all of which are lowercase and
not obviously macros, which write by value to their parameters.
This is non-intuitive to program which, being contrary to C semantics for code
appearing to be a regular function call. It is also causes Coverity to
conclude that __udelay() has an infinite loop, as all of its loop conditions
are constant.
Two of these macros (rdtsc() and rdtscl()) have only a handful of uses while
the vast majority of code uses the rdtscll() variant. rdtsc() and rdtscll()
are equivalent, while rdtscl() discards the high word.
Replace all 3 macros with a static inline which returns the complete tsc.
Most of this patch is a mechanical change of
- rdtscll($FOO);
+ $FOO = rdtsc();
And a diff of the generated assembly confirms that this is no change at all.
The single use of the old rdtsc() in emulate_privileged_op() is altered to use
the new rdtsc() and the rdmsr_writeback path to set eax/edx appropriately.
The pair of use of rdtscl() in __udelay() are extended to use full 64bit
values, which makes the overflow edge condition (and early exit from the loop)
far rarer.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
---
v2: Style adjustments, suggested by Jan
---
xen/arch/x86/apic.c | 4 ++--
xen/arch/x86/cpu/mcheck/mce.c | 2 +-
xen/arch/x86/delay.c | 4 ++--
xen/arch/x86/hvm/hvm.c | 4 ++--
xen/arch/x86/hvm/save.c | 4 ++--
xen/arch/x86/hvm/svm/svm.c | 2 +-
xen/arch/x86/platform_hypercall.c | 4 ++--
xen/arch/x86/smpboot.c | 2 +-
xen/arch/x86/time.c | 34 ++++++++++++++++------------------
xen/arch/x86/traps.c | 5 ++++-
xen/include/asm-x86/msr.h | 15 ++++++---------
xen/include/asm-x86/time.h | 4 +---
12 files changed, 40 insertions(+), 44 deletions(-)
diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index 39cd9e5..3217bdf 100644
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -1148,7 +1148,7 @@ static int __init calibrate_APIC_clock(void)
* We wrapped around just now. Let's start:
*/
if (cpu_has_tsc)
- rdtscll(t1);
+ t1 = rdtsc();
tt1 = apic_read(APIC_TMCCT);
/*
@@ -1159,7 +1159,7 @@ static int __init calibrate_APIC_clock(void)
tt2 = apic_read(APIC_TMCCT);
if (cpu_has_tsc)
- rdtscll(t2);
+ t2 = rdtsc();
/*
* The APIC bus clock counter is 32 bits only, it
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 05a86fb..3a3b4dc 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -235,7 +235,7 @@ static void mca_init_bank(enum mca_source who,
if (who == MCA_CMCI_HANDLER) {
mib->mc_ctrl2 = mca_rdmsr(MSR_IA32_MC0_CTL2 + bank);
- rdtscll(mib->mc_tsc);
+ mib->mc_tsc = rdtsc();
}
}
diff --git a/xen/arch/x86/delay.c b/xen/arch/x86/delay.c
index bc1772e..ef6bc5d 100644
--- a/xen/arch/x86/delay.c
+++ b/xen/arch/x86/delay.c
@@ -21,10 +21,10 @@ void __udelay(unsigned long usecs)
unsigned long ticks = usecs * (cpu_khz / 1000);
unsigned long s, e;
- rdtscl(s);
+ s = rdtsc();
do
{
rep_nop();
- rdtscl(e);
+ e = rdtsc();
} while ((e-s) < ticks);
}
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index a52c6e0..72e383f 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -292,7 +292,7 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc,
u64 at_tsc)
}
else
{
- rdtscll(tsc);
+ tsc = rdtsc();
}
delta_tsc = guest_tsc - tsc;
@@ -326,7 +326,7 @@ u64 hvm_get_guest_tsc_fixed(struct vcpu *v, uint64_t at_tsc)
}
else
{
- rdtscll(tsc);
+ tsc = rdtsc();
}
return tsc + v->arch.hvm_vcpu.cache_tsc_offset;
diff --git a/xen/arch/x86/hvm/save.c b/xen/arch/x86/hvm/save.c
index 6af19be..61f780d 100644
--- a/xen/arch/x86/hvm/save.c
+++ b/xen/arch/x86/hvm/save.c
@@ -36,7 +36,7 @@ void arch_hvm_save(struct domain *d, struct hvm_save_header
*hdr)
hdr->gtsc_khz = d->arch.tsc_khz;
/* Time when saving started */
- rdtscll(d->arch.hvm_domain.sync_tsc);
+ d->arch.hvm_domain.sync_tsc = rdtsc();
}
int arch_hvm_load(struct domain *d, struct hvm_save_header *hdr)
@@ -71,7 +71,7 @@ int arch_hvm_load(struct domain *d, struct hvm_save_header
*hdr)
hvm_set_rdtsc_exiting(d, 1);
/* Time when restore started */
- rdtscll(d->arch.hvm_domain.sync_tsc);
+ d->arch.hvm_domain.sync_tsc = rdtsc();
/* VGA state is not saved/restored, so we nobble the cache. */
d->arch.hvm_domain.stdvga.cache = 0;
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 018dd70..c83c483 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -805,7 +805,7 @@ static void svm_set_tsc_offset(struct vcpu *v, u64 offset,
u64 at_tsc)
if ( at_tsc )
host_tsc = at_tsc;
else
- rdtscll(host_tsc);
+ host_tsc = rdtsc();
offset = svm_get_tsc_offset(host_tsc, guest_tsc, vcpu_tsc_ratio(v));
}
diff --git a/xen/arch/x86/platform_hypercall.c
b/xen/arch/x86/platform_hypercall.c
index b427852..11c510d 100644
--- a/xen/arch/x86/platform_hypercall.c
+++ b/xen/arch/x86/platform_hypercall.c
@@ -146,7 +146,7 @@ static void resource_access(void *info)
{
unsigned long flags = 0;
/*
- * If next entry is MSR_IA32_TSC read, then the actual rdtscll
+ * If next entry is MSR_IA32_TSC read, then the actual rdtsc
* is performed together with current entry, with IRQ disabled.
*/
bool_t read_tsc = (i < ra->nr_done - 1 &&
@@ -159,7 +159,7 @@ static void resource_access(void *info)
if ( unlikely(read_tsc) )
{
- rdtscll(tsc);
+ tsc = rdtsc();
local_irq_restore(flags);
}
}
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index c54be7e..7ae561c 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -142,7 +142,7 @@ static void synchronize_tsc_master(unsigned int slave)
for ( i = 1; i <= 5; i++ )
{
- rdtscll(tsc_value);
+ tsc_value = rdtsc();
wmb();
atomic_inc(&tsc_count);
while ( atomic_read(&tsc_count) != (i<<1) )
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index b609938..994aa1a 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -261,10 +261,10 @@ static u64 init_pit_and_calibrate_tsc(void)
outb(CALIBRATE_LATCH & 0xff, PIT_CH2); /* LSB of count */
outb(CALIBRATE_LATCH >> 8, PIT_CH2); /* MSB of count */
- rdtscll(start);
+ start = rdtsc();
for ( count = 0; (inb(0x61) & 0x20) == 0; count++ )
continue;
- rdtscll(end);
+ end = rdtsc();
/* Error if the CTC doesn't behave itself. */
if ( count == 0 )
@@ -764,7 +764,7 @@ s_time_t get_s_time_fixed(u64 at_tsc)
if ( at_tsc )
tsc = at_tsc;
else
- rdtscll(tsc);
+ tsc = rdtsc();
delta = tsc - t->local_tsc_stamp;
now = t->stime_local_stamp + scale_delta(delta, &t->tsc_scale);
@@ -971,7 +971,7 @@ int cpu_frequency_change(u64 freq)
/* TSC-extrapolated time may be bogus after frequency change. */
/*t->stime_local_stamp = get_s_time();*/
t->stime_local_stamp = t->stime_master_stamp;
- rdtscll(curr_tsc);
+ curr_tsc = rdtsc();
t->local_tsc_stamp = curr_tsc;
set_time_scale(&t->tsc_scale, freq);
local_irq_enable();
@@ -1307,7 +1307,7 @@ static void time_calibration_tsc_rendezvous(void *_r)
if ( r->master_stime == 0 )
{
r->master_stime = read_platform_stime();
- rdtscll(r->master_tsc_stamp);
+ r->master_tsc_stamp = rdtsc();
}
atomic_inc(&r->semaphore);
@@ -1333,7 +1333,7 @@ static void time_calibration_tsc_rendezvous(void *_r)
}
}
- rdtscll(c->local_tsc_stamp);
+ c->local_tsc_stamp = rdtsc();
c->stime_local_stamp = get_s_time();
c->stime_master_stamp = r->master_stime;
@@ -1363,7 +1363,7 @@ static void time_calibration_std_rendezvous(void *_r)
mb(); /* receive signal /then/ read r->master_stime */
}
- rdtscll(c->local_tsc_stamp);
+ c->local_tsc_stamp = rdtsc();
c->stime_local_stamp = get_s_time();
c->stime_master_stamp = r->master_stime;
@@ -1397,7 +1397,7 @@ void init_percpu_time(void)
t->tsc_scale = per_cpu(cpu_time, 0).tsc_scale;
local_irq_save(flags);
- rdtscll(t->local_tsc_stamp);
+ t->local_tsc_stamp = rdtsc();
now = read_platform_stime();
local_irq_restore(flags);
@@ -1426,13 +1426,13 @@ static void __init tsc_check_writability(void)
if ( boot_cpu_has(X86_FEATURE_TSC_RELIABLE) )
return;
- rdtscll(tsc);
+ tsc = rdtsc();
if ( wrmsr_safe(MSR_IA32_TSC, 0) == 0 )
{
- uint64_t tmp, tmp2;
- rdtscll(tmp2);
+ uint64_t tmp, tmp2 = rdtsc();
+
write_tsc(tsc | (1ULL << 32));
- rdtscll(tmp);
+ tmp = rdtsc();
if ( ABS((s64)tmp - (s64)tmp2) < (1LL << 31) )
what = "only partially";
}
@@ -1868,7 +1868,7 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
*gtsc_khz = d->arch.tsc_khz;
break;
}
- rdtscll(tsc);
+ tsc = rdtsc();
*elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns);
*gtsc_khz = cpu_khz;
break;
@@ -1880,7 +1880,7 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
}
else
{
- rdtscll(tsc);
+ tsc = rdtsc();
*elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns) -
d->arch.vtsc_offset;
*gtsc_khz = 0; /* ignored by tsc_set_info */
@@ -1973,9 +1973,7 @@ void tsc_set_info(struct domain *d,
else {
/* when using native TSC, offset is nsec relative to power-on
* of physical machine */
- uint64_t tsc = 0;
- rdtscll(tsc);
- d->arch.vtsc_offset = scale_delta(tsc,&d->arch.vtsc_to_ns) -
+ d->arch.vtsc_offset = scale_delta(rdtsc(), &d->arch.vtsc_to_ns) -
elapsed_nsec;
}
break;
@@ -1994,7 +1992,7 @@ void tsc_set_info(struct domain *d,
* call set_tsc_offset() later from hvm_vcpu_reset_state() and they
* will sync their TSC to BSP's sync_tsc.
*/
- rdtscll(d->arch.hvm_domain.sync_tsc);
+ d->arch.hvm_domain.sync_tsc = rdtsc();
hvm_funcs.set_tsc_offset(d->vcpu[0],
d->vcpu[0]->arch.hvm_vcpu.cache_tsc_offset,
d->arch.hvm_domain.sync_tsc);
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 057a7af..14e2563 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2663,7 +2663,10 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
if ( v->domain->arch.vtsc )
pv_soft_rdtsc(v, regs, 0);
else
- rdtsc(regs->eax, regs->edx);
+ {
+ val = rdtsc();
+ goto rdmsr_writeback;
+ }
break;
case 0x32: /* RDMSR */
diff --git a/xen/include/asm-x86/msr.h b/xen/include/asm-x86/msr.h
index 52cae4b..4f233d5 100644
--- a/xen/include/asm-x86/msr.h
+++ b/xen/include/asm-x86/msr.h
@@ -71,17 +71,14 @@ static inline int wrmsr_safe(unsigned int msr, uint64_t val)
return _rc;
}
-#define rdtsc(low,high) \
- __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
+static inline uint64_t rdtsc(void)
+{
+ uint32_t low, high;
-#define rdtscl(low) \
- __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
+ __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high));
-#define rdtscll(val) do { \
- unsigned int _eax, _edx; \
- asm volatile("rdtsc" : "=a" (_eax), "=d" (_edx)); \
- (val) = ((unsigned long)_eax) | (((unsigned long)_edx)<<32); \
-} while(0)
+ return ((uint64_t)high << 32) | low;
+}
#define __write_tsc(val) wrmsrl(MSR_IA32_TSC, val)
#define write_tsc(val) ({ \
diff --git a/xen/include/asm-x86/time.h b/xen/include/asm-x86/time.h
index c4d82f6..39d6bf3 100644
--- a/xen/include/asm-x86/time.h
+++ b/xen/include/asm-x86/time.h
@@ -28,9 +28,7 @@
static inline cycles_t get_cycles(void)
{
- cycles_t c;
- rdtscll(c);
- return c;
+ return rdtsc();
}
unsigned long
--
1.7.10.4
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