diff options
| author | xypron.glpk@gmx.de | 2017-07-18 20:17:23 +0200 |
|---|---|---|
| committer | Alexander Graf | 2017-07-19 14:36:14 +0200 |
| commit | 8787b02e32dc8bcf7ed432adcb0d246c5c844985 (patch) | |
| tree | a9ace5282d8225e96e03eeaec99efa948b09bcf8 /lib | |
| parent | 91be9a77b758f5c785787260a1ed8f1b751ff49a (diff) | |
efi_loader: correctly implement 100ns conversion
In efi_set_timer we receive the trigger time in intervals of 100 ns.
We should convert it to intervals of 1000 ns by 64bit division.
The patch supplies function efi_div10 that uses multiplication to
implement the missing 64 bit division.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/efi_loader/efi_boottime.c | 49 |
1 files changed, 40 insertions, 9 deletions
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c index b8dfceae0c0..a89a6294062 100644 --- a/lib/efi_loader/efi_boottime.c +++ b/lib/efi_loader/efi_boottime.c @@ -81,6 +81,39 @@ efi_status_t efi_exit_func(efi_status_t ret) return ret; } +/* Low 32 bit */ +#define EFI_LOW32(a) (a & 0xFFFFFFFFULL) +/* High 32 bit */ +#define EFI_HIGH32(a) (a >> 32) + +/* + * 64bit division by 10 implemented as multiplication by 1 / 10 + * + * Decimals of one tenth: 0x1 / 0xA = 0x0.19999... + */ +#define EFI_TENTH 0x199999999999999A +static u64 efi_div10(u64 a) +{ + u64 prod; + u64 rem; + u64 ret; + + ret = EFI_HIGH32(a) * EFI_HIGH32(EFI_TENTH); + prod = EFI_HIGH32(a) * EFI_LOW32(EFI_TENTH); + rem = EFI_LOW32(prod); + ret += EFI_HIGH32(prod); + prod = EFI_LOW32(a) * EFI_HIGH32(EFI_TENTH); + rem += EFI_LOW32(prod); + ret += EFI_HIGH32(prod); + prod = EFI_LOW32(a) * EFI_LOW32(EFI_TENTH); + rem += EFI_HIGH32(prod); + ret += EFI_HIGH32(rem); + /* Round to nearest integer */ + if (rem >= (1 << 31)) + ++ret; + return ret; +} + void efi_signal_event(struct efi_event *event) { if (event->signaled) @@ -244,7 +277,7 @@ void efi_timer_check(void) continue; if (efi_events[i].trigger_type == EFI_TIMER_PERIODIC) { efi_events[i].trigger_next += - efi_events[i].trigger_time / 10; + efi_events[i].trigger_time; efi_events[i].signaled = 0; } efi_signal_event(&efi_events[i]); @@ -255,15 +288,13 @@ void efi_timer_check(void) efi_status_t efi_set_timer(struct efi_event *event, int type, uint64_t trigger_time) { - /* We don't have 64bit division available everywhere, so limit timer - * distances to 32bit bits. */ - u32 trigger32 = trigger_time; int i; - if (trigger32 < trigger_time) { - printf("WARNING: Truncating timer from %"PRIx64" to %x\n", - trigger_time, trigger32); - } + /* + * The parameter defines a multiple of 100ns. + * We use multiples of 1000ns. So divide by 10. + */ + trigger_time = efi_div10(trigger_time); for (i = 0; i < ARRAY_SIZE(efi_events); ++i) { if (event != &efi_events[i]) @@ -278,7 +309,7 @@ efi_status_t efi_set_timer(struct efi_event *event, int type, case EFI_TIMER_PERIODIC: case EFI_TIMER_RELATIVE: event->trigger_next = - timer_get_us() + (trigger32 / 10); + timer_get_us() + trigger_time; break; default: return EFI_INVALID_PARAMETER; |