From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3354 invoked by alias); 2 Sep 2002 16:34:27 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 3346 invoked from network); 2 Sep 2002 16:34:27 -0000 Received: from unknown (HELO dr-evil.shagadelic.org) (208.176.2.174) by sources.redhat.com with SMTP; 2 Sep 2002 16:34:27 -0000 Received: by dr-evil.shagadelic.org (Postfix, from userid 7518) id D56FC9869; Mon, 2 Sep 2002 09:34:26 -0700 (PDT) Date: Mon, 02 Sep 2002 09:34:00 -0000 From: Jason R Thorpe To: gdb-patches@sources.redhat.com Subject: [PATCH] i386nbsd_pc_in_sigtramp robustness Message-ID: <20020902093426.G4034@dr-evil.shagadelic.org> Mail-Followup-To: Jason R Thorpe , gdb-patches@sources.redhat.com Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="3xoW37o/FfUZJwQG" Content-Disposition: inline User-Agent: Mutt/1.2.5i Organization: Wasabi Systems, Inc. X-SW-Source: 2002-09/txt/msg00017.txt.bz2 --3xoW37o/FfUZJwQG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-length: 820 The strategy of comparing against hard-coded addresses to find the signal trampoline is a bad one; it is possible for the user to change the VM layout, and thus the location of the signal trampoline, with a kernel option. The following patch changes the i386-netbsd* targets to disassemble to find the trampoline, as is done for other NetBSD targets. Committed to trunk. * i386nbsd-tdep.c (i386nbsd_sigtramp_offset): New function. (i386nbsd_pc_in_sigtramp): Rewrite to use i386nbsd_sigtramp_offset. (i386nbsd_init_abi): Don't initialize tdep->sigtramp_start or tdep->sigtramp_end. (i386nbsd_sigtramp_start, i386nbsd_sigtramp_end): Remove. * config/i386/tm-nbsd.h (SIGTRAMP_START, SIGTRAMP_END) (i386bsd_sigtramp_start, i386bsd_sigtramp_end): Remove. -- -- Jason R. Thorpe --3xoW37o/FfUZJwQG Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=i386nbsd-sig-patch Content-length: 4920 Index: i386nbsd-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/i386nbsd-tdep.c,v retrieving revision 1.7 diff -c -r1.7 i386nbsd-tdep.c *** i386nbsd-tdep.c 1 Sep 2002 23:24:19 -0000 1.7 --- i386nbsd-tdep.c 2 Sep 2002 16:26:23 -0000 *************** *** 140,162 **** NULL /* next */ }; ! static int ! i386nbsd_pc_in_sigtramp (CORE_ADDR pc, char *name) { ! struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch); ! /* Check for libc-provided signal trampoline. */ ! if (nbsd_pc_in_sigtramp (pc, name)) ! return 1; ! /* FIXME: sigtramp_start/sigtramp_end need to go away; we should ! not be assuming the location of the kernel-provided trampoline! */ ! return (pc >= tdep->sigtramp_start && pc < tdep->sigtramp_end); } ! CORE_ADDR i386nbsd_sigtramp_start = 0xbfbfdf20; ! CORE_ADDR i386nbsd_sigtramp_end = 0xbfbfdff0; /* From . */ int i386nbsd_sc_pc_offset = 44; --- 140,240 ---- NULL /* next */ }; ! /* Under NetBSD/i386, signal handler invocations can be identified by the ! designated code sequence that is used to return from a signal handler. ! In particular, the return address of a signal handler points to the ! following code sequence: ! ! leal 0x10(%esp), %eax ! pushl %eax ! pushl %eax ! movl $0x127, %eax # __sigreturn14 ! int $0x80 ! ! Each instruction has a unique encoding, so we simply attempt to match ! the instruction the PC is pointing to with any of the above instructions. ! If there is a hit, we know the offset to the start of the designated ! sequence and can then check whether we really are executing in the ! signal trampoline. If not, -1 is returned, otherwise the offset from the ! start of the return sequence is returned. */ ! #define RETCODE_INSN1 0x8d ! #define RETCODE_INSN2 0x50 ! #define RETCODE_INSN3 0x50 ! #define RETCODE_INSN4 0xb8 ! #define RETCODE_INSN5 0xcd ! ! #define RETCODE_INSN2_OFF 4 ! #define RETCODE_INSN3_OFF 5 ! #define RETCODE_INSN4_OFF 6 ! #define RETCODE_INSN5_OFF 11 ! ! static const unsigned char sigtramp_retcode[] = { ! RETCODE_INSN1, 0x44, 0x24, 0x10, ! RETCODE_INSN2, ! RETCODE_INSN3, ! RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00, ! RETCODE_INSN5, 0x80, ! }; ! static LONGEST ! i386nbsd_sigtramp_offset (CORE_ADDR pc) ! { ! unsigned char ret[sizeof(sigtramp_retcode)], insn; ! LONGEST off; ! int i; ! ! if (read_memory_nobpt (pc, &insn, 1) != 0) ! return -1; ! ! switch (insn) ! { ! case RETCODE_INSN1: ! off = 0; ! break; ! ! case RETCODE_INSN2: ! /* INSN2 and INSN3 are the same. Read at the location of PC+1 ! to determine if we're actually looking at INSN2 or INSN3. */ ! if (read_memory_nobpt (pc + 1, &insn, 1) != 0) ! return -1; ! ! if (insn == RETCODE_INSN3) ! off = RETCODE_INSN2_OFF; ! else ! off = RETCODE_INSN3_OFF; ! break; ! ! case RETCODE_INSN4: ! off = RETCODE_INSN4_OFF; ! break; ! ! case RETCODE_INSN5: ! off = RETCODE_INSN5_OFF; ! break; ! ! default: ! return -1; ! } ! ! pc -= off; ! ! if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0) ! return -1; ! if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0) ! return off; ! return -1; } ! static int ! i386nbsd_pc_in_sigtramp (CORE_ADDR pc, char *name) ! { ! ! return (nbsd_pc_in_sigtramp (pc, name) ! || i386nbsd_sigtramp_offset (pc) >= 0); ! } /* From . */ int i386nbsd_sc_pc_offset = 44; *************** *** 175,184 **** /* NetBSD uses -freg-struct-return by default. */ tdep->struct_return = reg_struct_return; - - /* NetBSD uses a different memory layout. */ - tdep->sigtramp_start = i386nbsd_sigtramp_start; - tdep->sigtramp_end = i386nbsd_sigtramp_end; /* NetBSD has a `struct sigcontext' that's different from the origional 4.3 BSD. */ --- 253,258 ---- Index: config/i386/tm-nbsd.h =================================================================== RCS file: /cvs/src/src/gdb/config/i386/tm-nbsd.h,v retrieving revision 1.13 diff -c -r1.13 tm-nbsd.h *** config/i386/tm-nbsd.h 30 Jun 2002 17:22:57 -0000 1.13 --- config/i386/tm-nbsd.h 2 Sep 2002 16:26:26 -0000 *************** *** 23,38 **** #include "i386/tm-i386.h" - /* These defines allow the recognition of sigtramps as a function name - . - - FIXME: kettenis/2002-05-12: Of course these defines will have to go - if we go truly "multi-arch", but I don't know yet how to get rid of - them. */ - - #define SIGTRAMP_START(pc) i386bsd_sigtramp_start (pc) - #define SIGTRAMP_END(pc) i386bsd_sigtramp_end (pc) - extern CORE_ADDR i386bsd_sigtramp_start (CORE_ADDR pc); - extern CORE_ADDR i386bsd_sigtramp_end (CORE_ADDR pc); - #endif /* TM_NBSD_H */ --- 23,26 ---- --3xoW37o/FfUZJwQG--