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33a58980ff
The generic VDSO implementation uses the Y2038 safe clock_gettime64() and
clock_getres_time64() syscalls as fallback for 32bit VDSO. This breaks
seccomp setups because these syscalls might be not (yet) allowed.
Implement the 32bit variants which use the legacy syscalls and select the
variant in the core library.
The 64bit time variants are not removed because they are required for the
time64 based vdso accessors.
Fixes: 00b26474c2 ("lib/vdso: Provide generic VDSO implementation")
Reported-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20190728131648.971361611@linutronix.de
167 lines
4.0 KiB
C
167 lines
4.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2018 ARM Limited
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*/
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#ifndef __ASM_VDSO_GETTIMEOFDAY_H
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#define __ASM_VDSO_GETTIMEOFDAY_H
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#ifndef __ASSEMBLY__
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#include <asm/unistd.h>
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#include <uapi/linux/time.h>
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#include <asm/vdso/compat_barrier.h>
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#define __VDSO_USE_SYSCALL ULLONG_MAX
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#define VDSO_HAS_CLOCK_GETRES 1
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#define VDSO_HAS_32BIT_FALLBACK 1
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static __always_inline
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int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
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struct timezone *_tz)
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{
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register struct timezone *tz asm("r1") = _tz;
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register struct __kernel_old_timeval *tv asm("r0") = _tv;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_gettimeofday;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (tv), "r" (tz), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_gettime64;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
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{
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register struct old_timespec32 *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_gettime;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
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{
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register struct __kernel_timespec *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_getres_time64;
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/* The checks below are required for ABI consistency with arm */
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if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
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return -EINVAL;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline
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int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
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{
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register struct old_timespec32 *ts asm("r1") = _ts;
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register clockid_t clkid asm("r0") = _clkid;
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register long ret asm ("r0");
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register long nr asm("r7") = __NR_compat_clock_getres;
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/* The checks below are required for ABI consistency with arm */
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if ((_clkid >= MAX_CLOCKS) && (_ts == NULL))
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return -EINVAL;
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asm volatile(
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" swi #0\n"
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: "=r" (ret)
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: "r" (clkid), "r" (ts), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
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{
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u64 res;
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/*
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* clock_mode == 0 implies that vDSO are enabled otherwise
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* fallback on syscall.
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*/
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if (clock_mode)
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return __VDSO_USE_SYSCALL;
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/*
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* This isb() is required to prevent that the counter value
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* is speculated.
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*/
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isb();
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asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (res));
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/*
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* This isb() is required to prevent that the seq lock is
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* speculated.
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*/
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isb();
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return res;
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}
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static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
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{
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const struct vdso_data *ret;
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/*
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* This simply puts &_vdso_data into ret. The reason why we don't use
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* `ret = _vdso_data` is that the compiler tends to optimise this in a
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* very suboptimal way: instead of keeping &_vdso_data in a register,
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* it goes through a relocation almost every time _vdso_data must be
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* accessed (even in subfunctions). This is both time and space
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* consuming: each relocation uses a word in the code section, and it
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* has to be loaded at runtime.
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*
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* This trick hides the assignment from the compiler. Since it cannot
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* track where the pointer comes from, it will only use one relocation
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* where __arch_get_vdso_data() is called, and then keep the result in
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* a register.
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*/
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asm volatile("mov %0, %1" : "=r"(ret) : "r"(_vdso_data));
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return ret;
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
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