1 /* 2 * Copyright (c) 2003 Russell King <rmk (at) arm.linux.org.uk> 3 * Copyright (c) 2011-2013 Denys Vlasenko <vda.linux (at) googlemail.com> 4 * Copyright (c) 2011-2015 Dmitry V. Levin <ldv (at) altlinux.org> 5 * Copyright (c) 2015-2018 The strace developers. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 /* Return codes: 1 - ok, 0 - ignore, other - error. */ 32 static int 33 arch_get_scno(struct tcb *tcp) 34 { 35 kernel_ulong_t scno = 0; 36 37 /* Note: we support only 32-bit CPUs, not 26-bit */ 38 39 #if !defined(__ARM_EABI__) || ENABLE_ARM_OABI 40 if (arm_regs.ARM_cpsr & 0x20) { 41 /* Thumb mode */ 42 goto scno_in_r7; 43 } 44 /* ARM mode */ 45 /* Check EABI/OABI by examining SVC insn's low 24 bits */ 46 errno = 0; 47 scno = ptrace(PTRACE_PEEKTEXT, tcp->pid, (void *)(arm_regs.ARM_pc - 4), NULL); 48 if (errno) 49 return -1; 50 /* EABI syscall convention? */ 51 if (scno != 0xef000000) { 52 /* No, it's OABI */ 53 if ((scno & 0x0ff00000) != 0x0f900000) { 54 error_msg("pid %d unknown syscall trap 0x%08lx", 55 tcp->pid, scno); 56 return -1; 57 } 58 /* Fixup the syscall number */ 59 scno &= 0x000fffff; 60 } else { 61 scno_in_r7: 62 scno = arm_regs.ARM_r7; 63 } 64 #else /* __ARM_EABI__ || !ENABLE_ARM_OABI */ 65 66 scno = arm_regs.ARM_r7; 67 68 #endif 69 70 /* 71 * Do some sanity checks to figure out 72 * whether it's really a syscall entry. 73 */ 74 if (arm_regs.ARM_ip && !scno_in_range(scno)) { 75 debug_msg("pid %d stray syscall exit: ARM_ip = %ld, scno = %ld", 76 tcp->pid, arm_regs.ARM_ip, scno); 77 return 0; 78 } 79 80 tcp->scno = scno; 81 return 1; 82 } 83
