/usr/include/xenomai/asm-x86/switch_64.h is in libxenomai-dev 2.6.2.1-2ubuntu2.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 | /*
* Copyright (C) 2007 Philippe Gerum <rpm@xenomai.org>.
*
* Xenomai is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2 of the License,
* or (at your option) any later version.
*
* Xenomai is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Xenomai; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#ifndef _XENO_ASM_X86_SWITCH_64_H
#define _XENO_ASM_X86_SWITCH_64_H
#define _XENO_ASM_X86_SWITCH_H
#ifndef __KERNEL__
#error "Pure kernel header included from user-space!"
#endif
struct xnarch_x8664_initstack {
#ifdef CONFIG_CC_STACKPROTECTOR
unsigned long canary;
#endif
unsigned long rbp;
unsigned long eflags;
unsigned long arg;
unsigned long entry;
};
#ifdef CONFIG_CC_STACKPROTECTOR
/*
* We have an added complexity with -fstack-protector, due to the
* hybrid scheduling between user- and kernel-based Xenomai threads,
* for which we do not have any underlying task_struct. We update the
* current stack canary for incoming user-based threads exactly the
* same way as Linux does. However, we handle the case of incoming
* kernel-based Xenomai threads differently: in that case, the canary
* value shall be given by our caller.
*
* In the latter case, the update logic is jointly handled by
* xeno_switch_kernel_prologue and xeno_switch_kernel_canary; the
* former clears %rax whenever the incoming thread is kernel-based,
* and with that information, the latter checks %rax to determine
* whether the canary should be picked from the current task struct,
* or from %r8. %r8 is set ealier to the proper canary value passed by
* our caller (i.e. in_tcb->canary).
*
* This code is based on the assumption that no scheduler exchange can
* happen between Linux and Xenomai for kernel-based Xenomai threads,
* i.e. the only way to schedule a kernel-based Xenomai thread in goes
* through xnarch_switch_to(), never via schedule(). This is turn
* means that neither %rax or %r8 could be clobbered once set by
* xeno_switch_kernel_prologue, since the only way of branching to the
* incoming kernel-based thread is via retq. Besides, we may take for
* granted that %rax can't be null upon return from __switch_to, since
* the latter returns prev_p, which cannot be NULL, so the logic
* cannot be confused by incoming user-based threads.
*
* Yeah, I know, it's awfully convoluted, but I'm not even sorry for
* this. --rpm
*/
#define xeno_init_kernel_canary \
"popq %%r8\n\t" \
"movq %%r8,"__percpu_arg([gs_canary])"\n\t"
#define xeno_init_canary_oparam \
[gs_canary] "=m" (per_cpu_var(irq_stack_union.stack_canary))
#define xeno_switch_canary_setup(c) \
register long __kcanary __asm__ ("r8") = (c)
#define xeno_switch_kernel_prologue \
"xor %%rax, %%rax\n\t"
#define xeno_switch_kernel_canary \
"testq %%rax, %%rax\n\t" \
"jnz 8f\n\t" \
"movq %%r8,"__percpu_arg([gs_canary])"\n\t" \
"jmp 9f\n\t"
#define xeno_switch_user_canary \
"movq "__percpu_arg([current_task])",%%rsi\n\t" \
"movq %P[user_canary](%%rsi),%%r8\n\t" \
"movq %%r8,"__percpu_arg([gs_canary])"\n\t"
#define xeno_switch_canary_oparam \
, [gs_canary] "=m" (per_cpu_var(irq_stack_union.stack_canary))
#define xeno_switch_canary_iparam \
, [user_canary] "i" (offsetof(struct task_struct, stack_canary)) \
, [current_task] "m" (per_cpu_var(current_task)) \
, "r" (__kcanary)
#define __SWITCH_CLOBBER_LIST , "r9", "r10", "r11", "r12", "r13", "r14", "r15"
#define __HEAD_CLOBBER_LIST , "rdi", "r8"
#else /* CC_STACKPROTECTOR */
#define xeno_switch_canary_setup(c) (void)(c)
#define xeno_init_kernel_canary
#define xeno_init_canary_oparam
#define xeno_switch_kernel_prologue
#define xeno_switch_kernel_canary
#define xeno_switch_user_canary
#define xeno_switch_canary_oparam
#define xeno_switch_canary_iparam
#define __SWITCH_CLOBBER_LIST , "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
#define __HEAD_CLOBBER_LIST , "rdi"
#endif /* CC_STACKPROTECTOR */
#define xnarch_switch_threads(prev,next,p_rsp,n_rsp,p_rip,n_rip,kcanary) \
({ \
long __rdi, __rsi, __rax, __rbx, __rcx, __rdx; \
xeno_switch_canary_setup(kcanary); \
\
asm volatile("pushfq\n\t" \
"pushq %%rbp\n\t" \
"movq %%rsi, %%rbp\n\t" \
"movq %%rsp, (%%rdx)\n\t" \
"movq $1f, (%%rax)\n\t" \
"movq (%%rcx), %%rsp\n\t" \
"pushq (%%rbx)\n\t" \
"cmpq %%rsi, %%rdi\n\t" \
"jz 0f\n\t" \
"testq %%rsi, %%rsi\n\t" \
"jnz __switch_to\n\t" \
xeno_switch_kernel_prologue \
"0:\n\t" \
"ret\n\t" \
"1:\n\t" \
xeno_switch_kernel_canary \
"8:\n\t" \
xeno_switch_user_canary \
"9:\n\t" \
"movq %%rbp, %%rsi\n\t" \
"popq %%rbp\n\t" \
"popfq\n\t" \
: "=S" (__rsi), "=D" (__rdi), "=a" (__rax), \
"=b" (__rbx), "=c" (__rcx), "=d" (__rdx) \
xeno_switch_canary_oparam \
: "0" (next), "1" (prev), "5" (p_rsp), "4" (n_rsp), \
"2" (p_rip), "3" (n_rip) \
xeno_switch_canary_iparam \
: "memory", "cc" __SWITCH_CLOBBER_LIST); \
})
#define xnarch_thread_head() \
asm volatile(".globl __thread_head\n\t" \
"__thread_head:\n\t" \
xeno_init_kernel_canary \
"popq %%rbp\n\t" \
"popfq\n\t" \
"popq %%rdi\n\t" \
"ret\n\t" \
: xeno_init_canary_oparam \
: /* no input */ \
: "cc", "memory" __HEAD_CLOBBER_LIST)
asmlinkage void __thread_head(void);
#endif /* !_XENO_ASM_X86_SWITCH_64_H */
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