diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/vdso/gettimeofday.h | 26 | ||||
| -rw-r--r-- | arch/s390/include/asm/vdso/gettimeofday.h | 7 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/gettimeofday.h | 44 |
4 files changed, 42 insertions, 36 deletions
diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h index 78302f6c2580..c6390890a60c 100644 --- a/arch/powerpc/include/asm/vdso/gettimeofday.h +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h @@ -13,6 +13,17 @@ #define VDSO_HAS_TIME 1 +/* + * powerpc specific delta calculation. + * + * This variant removes the masking of the subtraction because the + * clocksource mask of all VDSO capable clocksources on powerpc is U64_MAX + * which would result in a pointless operation. The compiler cannot + * optimize it away as the mask comes from the vdso data and is not compile + * time constant. + */ +#define VDSO_DELTA_NOMASK 1 + static __always_inline int do_syscall_2(const unsigned long _r0, const unsigned long _r3, const unsigned long _r4) { @@ -104,21 +115,6 @@ static inline bool vdso_clocksource_ok(const struct vdso_data *vd) } #define vdso_clocksource_ok vdso_clocksource_ok -/* - * powerpc specific delta calculation. - * - * This variant removes the masking of the subtraction because the - * clocksource mask of all VDSO capable clocksources on powerpc is U64_MAX - * which would result in a pointless operation. The compiler cannot - * optimize it away as the mask comes from the vdso data and is not compile - * time constant. - */ -static __always_inline u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult) -{ - return (cycles - last) * mult; -} -#define vdso_calc_delta vdso_calc_delta - #ifndef __powerpc64__ static __always_inline u64 vdso_shift_ns(u64 ns, unsigned long shift) { diff --git a/arch/s390/include/asm/vdso/gettimeofday.h b/arch/s390/include/asm/vdso/gettimeofday.h index db84942eb78f..7937765ccfa5 100644 --- a/arch/s390/include/asm/vdso/gettimeofday.h +++ b/arch/s390/include/asm/vdso/gettimeofday.h @@ -6,16 +6,13 @@ #define VDSO_HAS_CLOCK_GETRES 1 +#define VDSO_DELTA_NOMASK 1 + #include <asm/syscall.h> #include <asm/timex.h> #include <asm/unistd.h> #include <linux/compiler.h> -#define vdso_calc_delta __arch_vdso_calc_delta -static __always_inline u64 __arch_vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult) -{ - return (cycles - last) * mult; -} static __always_inline const struct vdso_data *__arch_get_vdso_data(void) { diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index fe196f49d278..07e8817278a4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -169,6 +169,7 @@ config X86 select GENERIC_TIME_VSYSCALL select GENERIC_GETTIMEOFDAY select GENERIC_VDSO_TIME_NS + select GENERIC_VDSO_OVERFLOW_PROTECT select GUP_GET_PXX_LOW_HIGH if X86_PAE select HARDIRQS_SW_RESEND select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h index 8e048ca980df..0ef36190abe6 100644 --- a/arch/x86/include/asm/vdso/gettimeofday.h +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -300,7 +300,7 @@ static inline bool arch_vdso_cycles_ok(u64 cycles) #define vdso_cycles_ok arch_vdso_cycles_ok /* - * x86 specific delta calculation. + * x86 specific calculation of nanoseconds for the current cycle count * * The regular implementation assumes that clocksource reads are globally * monotonic. The TSC can be slightly off across sockets which can cause @@ -308,8 +308,8 @@ static inline bool arch_vdso_cycles_ok(u64 cycles) * jump. * * Therefore it needs to be verified that @cycles are greater than - * @last. If not then use @last, which is the base time of the current - * conversion period. + * @vd->cycles_last. If not then use @vd->cycles_last, which is the base + * time of the current conversion period. * * This variant also uses a custom mask because while the clocksource mask of * all the VDSO capable clocksources on x86 is U64_MAX, the above code uses @@ -317,25 +317,37 @@ static inline bool arch_vdso_cycles_ok(u64 cycles) * declares everything with the MSB/Sign-bit set as invalid. Therefore the * effective mask is S64_MAX. */ -static __always_inline -u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult) +static __always_inline u64 vdso_calc_ns(const struct vdso_data *vd, u64 cycles, u64 base) { - /* - * Due to the MSB/Sign-bit being used as invalid marker (see - * arch_vdso_cycles_valid() above), the effective mask is S64_MAX. - */ - u64 delta = (cycles - last) & S64_MAX; + u64 delta = cycles - vd->cycle_last; /* - * Due to the above mentioned TSC wobbles, filter out negative motion. - * Per the above masking, the effective sign bit is now bit 62. + * Negative motion and deltas which can cause multiplication + * overflow require special treatment. This check covers both as + * negative motion is guaranteed to be greater than @vd::max_cycles + * due to unsigned comparison. + * + * Due to the MSB/Sign-bit being used as invalid marker (see + * arch_vdso_cycles_valid() above), the effective mask is S64_MAX, + * but that case is also unlikely and will also take the unlikely path + * here. */ - if (unlikely(delta & (1ULL << 62))) - return 0; + if (unlikely(delta > vd->max_cycles)) { + /* + * Due to the above mentioned TSC wobbles, filter out + * negative motion. Per the above masking, the effective + * sign bit is now bit 62. + */ + if (delta & (1ULL << 62)) + return base >> vd->shift; + + /* Handle multiplication overflow gracefully */ + return mul_u64_u32_add_u64_shr(delta & S64_MAX, vd->mult, base, vd->shift); + } - return delta * mult; + return ((delta * vd->mult) + base) >> vd->shift; } -#define vdso_calc_delta vdso_calc_delta +#define vdso_calc_ns vdso_calc_ns #endif /* !__ASSEMBLY__ */ |