diff options
Diffstat (limited to 'arch/x86/include/asm/vdso')
| -rw-r--r-- | arch/x86/include/asm/vdso/getrandom.h | 42 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/gettimeofday.h | 45 | ||||
| -rw-r--r-- | arch/x86/include/asm/vdso/vsyscall.h | 9 |
3 files changed, 76 insertions, 20 deletions
diff --git a/arch/x86/include/asm/vdso/getrandom.h b/arch/x86/include/asm/vdso/getrandom.h new file mode 100644 index 000000000000..ff5334ad32a0 --- /dev/null +++ b/arch/x86/include/asm/vdso/getrandom.h @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. + */ +#ifndef __ASM_VDSO_GETRANDOM_H +#define __ASM_VDSO_GETRANDOM_H + +#ifndef __ASSEMBLY__ + +#include <asm/unistd.h> +#include <asm/vvar.h> + +/** + * getrandom_syscall - Invoke the getrandom() syscall. + * @buffer: Destination buffer to fill with random bytes. + * @len: Size of @buffer in bytes. + * @flags: Zero or more GRND_* flags. + * Returns: The number of random bytes written to @buffer, or a negative value indicating an error. + */ +static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags) +{ + long ret; + + asm ("syscall" : "=a" (ret) : + "0" (__NR_getrandom), "D" (buffer), "S" (len), "d" (flags) : + "rcx", "r11", "memory"); + + return ret; +} + +#define __vdso_rng_data (VVAR(_vdso_rng_data)) + +static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void) +{ + if (IS_ENABLED(CONFIG_TIME_NS) && __vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS) + return (void *)&__vdso_rng_data + ((void *)&__timens_vdso_data - (void *)&__vdso_data); + return &__vdso_rng_data; +} + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETRANDOM_H */ diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h index c81858d903dc..b2d2df026f6e 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 @@ -317,27 +317,36 @@ 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 invald 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_ok() 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 - -int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts); +#define vdso_calc_ns vdso_calc_ns #endif /* !__ASSEMBLY__ */ diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h index be199a9b2676..67fedf1698b5 100644 --- a/arch/x86/include/asm/vdso/vsyscall.h +++ b/arch/x86/include/asm/vdso/vsyscall.h @@ -4,13 +4,11 @@ #ifndef __ASSEMBLY__ -#include <linux/hrtimer.h> #include <linux/timekeeper_internal.h> #include <vdso/datapage.h> #include <asm/vgtod.h> #include <asm/vvar.h> -DEFINE_VVAR(struct vdso_data, _vdso_data); /* * Update the vDSO data page to keep in sync with kernel timekeeping. */ @@ -21,6 +19,13 @@ struct vdso_data *__x86_get_k_vdso_data(void) } #define __arch_get_k_vdso_data __x86_get_k_vdso_data +static __always_inline +struct vdso_rng_data *__x86_get_k_vdso_rng_data(void) +{ + return &_vdso_rng_data; +} +#define __arch_get_k_vdso_rng_data __x86_get_k_vdso_rng_data + /* The asm-generic header needs to be included after the definitions above */ #include <asm-generic/vdso/vsyscall.h> |