| 1 |
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| 2 | #ifndef _ASM_ALPHA_SYSCALL_H
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| 3 | #define _ASM_ALPHA_SYSCALL_H
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| 4 |
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| 5 | #include <uapi/linux/audit.h>
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| 6 | #include <linux/audit.h>
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| 7 | #include <linux/sched.h>
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| 8 | #include <linux/types.h>
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| 9 | #include <asm/ptrace.h>
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| 10 |
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| 11 | extern void *sys_call_table[];
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| 12 |
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| 13 | static inline int syscall_get_arch(struct task_struct *task)
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| 14 | {
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| 15 | return AUDIT_ARCH_ALPHA;
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| 16 | }
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| 17 |
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| 18 | static inline long syscall_get_return_value(struct task_struct *task,
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| 19 | struct pt_regs *regs)
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| 20 | {
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| 21 | return regs->r19 ? -(long)regs->r0 : (long)regs->r0;
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| 22 | }
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| 23 |
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| 24 | static inline long syscall_get_error(struct task_struct *task,
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| 25 | struct pt_regs *regs)
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| 26 | {
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| 27 | return regs->r19 ? -(long)regs->r0 : 0;
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| 28 | }
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| 29 |
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| 30 |
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| 31 | |
| 32 | * Alpha syscall ABI / kernel conventions:
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| 33 | * - PAL provides syscall number in r0 on entry.
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| 34 | * - The kernel tracks the active syscall number in regs->r1 (mutable) and
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| 35 | * preserves the original syscall number in regs->r2 for rollback/restart.
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| 36 | * - Return value is in regs->r0, with regs->r19 ("a3") as the error flag
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| 37 | * (0=success, 1=error; on error regs->r0 holds positive errno).
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| 38 |
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| 39 |
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| 40 | static inline long syscall_get_nr(struct task_struct *task,
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| 41 | struct pt_regs *regs)
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| 42 | {
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| 43 | return (long)regs->r1;
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| 44 | }
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| 45 |
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| 46 | static inline void syscall_set_nr(struct task_struct *task,
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| 47 | struct pt_regs *regs,
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| 48 | long nr)
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| 49 | {
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| 50 | regs->r1 = (unsigned long)nr;
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| 51 | }
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| 52 |
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| 53 | |
| 54 | * Syscall arguments:
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| 55 | * regs->r16..regs->r21 carry up to 6 syscall arguments on entry.
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| 56 | * Note: regs->r19 is also used as "a3" (error flag) on syscall return.
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| 57 |
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| 58 |
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| 59 | static inline void syscall_get_arguments(struct task_struct *task,
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| 60 | struct pt_regs *regs,
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| 61 | unsigned long *args)
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| 62 | {
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| 63 | args[0] = regs->r16;
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| 64 | args[1] = regs->r17;
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| 65 | args[2] = regs->r18;
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| 66 | args[3] = regs->r19;
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| 67 | args[4] = regs->r20;
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| 68 | args[5] = regs->r21;
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| 69 | }
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| 70 |
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| 71 | static inline void syscall_set_arguments(struct task_struct *task,
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| 72 | struct pt_regs *regs,
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| 73 | const unsigned long *args)
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| 74 | {
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| 75 | regs->r16 = args[0];
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| 76 | regs->r17 = args[1];
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| 77 | regs->r18 = args[2];
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| 78 | regs->r19 = args[3];
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| 79 | regs->r20 = args[4];
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| 80 | regs->r21 = args[5];
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| 81 | }
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| 82 | |
| 83 | * Set return value for a syscall.
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| 84 | * Alpha uses r0 for return value and r19 ("a3") as the error indicator:
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| 85 | * a3 = 0 => success
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| 86 | * a3 = 1 => error, and userspace interprets r0 as errno (positive).
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| 87 | *
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| 88 | * The kernel reports errors to userspace by setting a3=1 and placing a
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| 89 | * positive errno value in r0. Some syscall paths do this in entry.S,
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| 90 | * while others (e.g. seccomp/ptrace helpers) use syscall_set_return_value().
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| 91 |
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| 92 |
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| 93 | static inline void syscall_set_return_value(struct task_struct *task,
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| 94 | struct pt_regs *regs,
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| 95 | int error, long val)
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| 96 | {
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| 97 |
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| 98 | if (error) {
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| 99 |
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| 100 | regs->r0 = (unsigned long)(-error);
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| 101 | regs->r19 = 1;
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| 102 | } else {
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| 103 | regs->r0 = (unsigned long)val;
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| 104 | regs->r19 = 0;
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| 105 | }
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| 106 | }
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| 107 |
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| 108 |
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| 109 |
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| 110 | static inline void syscall_rollback(struct task_struct *task,
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| 111 | struct pt_regs *regs)
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| 112 | {
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| 113 | unsigned long nr = task_thread_info(task)->syscall_saved_nr;
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| 114 |
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| 115 | regs->r1 = nr;
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| 116 | }
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| 117 |
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| 118 | static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
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| 119 | {
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| 120 | return false;
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| 121 | }
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| 122 | #endif
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