5541992e51
The 'syscall' instruction clobbers '%rcx' and '%r11', but they are not
listed in the inline Assembly that performs the syscall instruction.
No real bug is found. It wasn't buggy by luck because '%rcx' and '%r11'
are caller-saved registers, and not used in the functions, and the
functions are never inlined.
Add them to the clobber list for code correctness.
Fixes: f1c2bb8b9964ed31de988910f8b1cfb586d30091 ("um: implement a x86_64 vDSO")
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
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*
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* This vDSO turns all calls into a syscall so that UML can trap them.
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*/
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/* Disable profiling for userspace code */
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#define DISABLE_BRANCH_PROFILING
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#include <linux/time.h>
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#include <linux/getcpu.h>
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#include <asm/unistd.h>
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int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
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{
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long ret;
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asm("syscall"
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: "=a" (ret)
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: "0" (__NR_clock_gettime), "D" (clock), "S" (ts)
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: "rcx", "r11", "memory");
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return ret;
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}
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int clock_gettime(clockid_t, struct __kernel_old_timespec *)
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__attribute__((weak, alias("__vdso_clock_gettime")));
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int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
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{
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long ret;
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asm("syscall"
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: "=a" (ret)
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: "0" (__NR_gettimeofday), "D" (tv), "S" (tz)
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: "rcx", "r11", "memory");
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return ret;
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}
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int gettimeofday(struct __kernel_old_timeval *, struct timezone *)
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__attribute__((weak, alias("__vdso_gettimeofday")));
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__kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
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{
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long secs;
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asm volatile("syscall"
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: "=a" (secs)
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: "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
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return secs;
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}
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__kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
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long
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__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
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{
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/*
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* UML does not support SMP, we can cheat here. :)
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*/
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if (cpu)
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*cpu = 0;
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if (node)
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*node = 0;
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return 0;
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}
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long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
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__attribute__((weak, alias("__vdso_getcpu")));
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