| David Howells | 4a3b989 | 2009-06-11 13:05:24 +0100 | [diff] [blame] | 1 | /* syscall parameter access functions |
| 2 | * |
| 3 | * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved. |
| 4 | * Written by David Howells (dhowells@redhat.com) |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public Licence |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the Licence, or (at your option) any later version. |
| 10 | */ |
| 11 | |
| 12 | #ifndef _ASM_SYSCALL_H |
| 13 | #define _ASM_SYSCALL_H |
| 14 | |
| 15 | #include <linux/err.h> |
| 16 | #include <asm/ptrace.h> |
| 17 | |
| 18 | /* |
| 19 | * Get the system call number or -1 |
| 20 | */ |
| 21 | static inline long syscall_get_nr(struct task_struct *task, |
| 22 | struct pt_regs *regs) |
| 23 | { |
| 24 | return regs->syscallno; |
| 25 | } |
| 26 | |
| 27 | /* |
| 28 | * Restore the clobbered GR8 register |
| 29 | * (1st syscall arg was overwritten with syscall return or error) |
| 30 | */ |
| 31 | static inline void syscall_rollback(struct task_struct *task, |
| 32 | struct pt_regs *regs) |
| 33 | { |
| 34 | regs->gr8 = regs->orig_gr8; |
| 35 | } |
| 36 | |
| 37 | /* |
| 38 | * See if the syscall return value is an error, returning it if it is and 0 if |
| 39 | * not |
| 40 | */ |
| 41 | static inline long syscall_get_error(struct task_struct *task, |
| 42 | struct pt_regs *regs) |
| 43 | { |
| 44 | return IS_ERR_VALUE(regs->gr8) ? regs->gr8 : 0; |
| 45 | } |
| 46 | |
| 47 | /* |
| 48 | * Get the syscall return value |
| 49 | */ |
| 50 | static inline long syscall_get_return_value(struct task_struct *task, |
| 51 | struct pt_regs *regs) |
| 52 | { |
| 53 | return regs->gr8; |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Set the syscall return value |
| 58 | */ |
| 59 | static inline void syscall_set_return_value(struct task_struct *task, |
| 60 | struct pt_regs *regs, |
| 61 | int error, long val) |
| 62 | { |
| 63 | if (error) |
| 64 | regs->gr8 = -error; |
| 65 | else |
| 66 | regs->gr8 = val; |
| 67 | } |
| 68 | |
| 69 | /* |
| 70 | * Retrieve the system call arguments |
| 71 | */ |
| 72 | static inline void syscall_get_arguments(struct task_struct *task, |
| 73 | struct pt_regs *regs, |
| 74 | unsigned int i, unsigned int n, |
| 75 | unsigned long *args) |
| 76 | { |
| 77 | /* |
| 78 | * Do this simply for now. If we need to start supporting |
| 79 | * fetching arguments from arbitrary indices, this will need some |
| 80 | * extra logic. Presently there are no in-tree users that depend |
| 81 | * on this behaviour. |
| 82 | */ |
| 83 | BUG_ON(i); |
| 84 | |
| 85 | /* Argument pattern is: GR8, GR9, GR10, GR11, GR12, GR13 */ |
| 86 | switch (n) { |
| 87 | case 6: args[5] = regs->gr13; |
| 88 | case 5: args[4] = regs->gr12; |
| 89 | case 4: args[3] = regs->gr11; |
| 90 | case 3: args[2] = regs->gr10; |
| 91 | case 2: args[1] = regs->gr9; |
| 92 | case 1: args[0] = regs->gr8; |
| 93 | break; |
| 94 | default: |
| 95 | BUG(); |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * Alter the system call arguments |
| 101 | */ |
| 102 | static inline void syscall_set_arguments(struct task_struct *task, |
| 103 | struct pt_regs *regs, |
| 104 | unsigned int i, unsigned int n, |
| 105 | const unsigned long *args) |
| 106 | { |
| 107 | /* Same note as above applies */ |
| 108 | BUG_ON(i); |
| 109 | |
| 110 | switch (n) { |
| 111 | case 6: regs->gr13 = args[5]; |
| 112 | case 5: regs->gr12 = args[4]; |
| 113 | case 4: regs->gr11 = args[3]; |
| 114 | case 3: regs->gr10 = args[2]; |
| 115 | case 2: regs->gr9 = args[1]; |
| 116 | case 1: regs->gr8 = args[0]; |
| 117 | break; |
| 118 | default: |
| 119 | BUG(); |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | #endif /* _ASM_SYSCALL_H */ |