From patchwork Thu Apr 9 15:42:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pedro Alves X-Patchwork-Id: 6115 Received: (qmail 85064 invoked by alias); 9 Apr 2015 15:42:13 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 84963 invoked by uid 89); 9 Apr 2015 15:42:11 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL, BAYES_00, SPF_HELO_PASS, SPF_PASS, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Thu, 09 Apr 2015 15:42:09 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t39Fg5IR019447 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 9 Apr 2015 11:42:06 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t39Fg3Bu015759; Thu, 9 Apr 2015 11:42:04 -0400 Message-ID: <55269DCB.7040100@redhat.com> Date: Thu, 09 Apr 2015 16:42:03 +0100 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: GDB Patches , Yao Qi Subject: [PATCH][AT_ENTRY version] PR13858 - Can't do displaced stepping with no symbols Following up from: https://sourceware.org/ml/gdb-patches/2015-04/msg00331.html Yao, could you give this a quick try on ARM? ARM is the only touched port that I can't easily test. I pushed it to the users/palves/disp-step-no-symbols branch. Just testing the new gdb.base/step-over-no-symbols.exp test should be sufficient. Thanks, Pedro Alves --- From 707d8ada790d0187748dfd2f42727f10868377e7 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Thu, 9 Apr 2015 14:59:58 +0100 Subject: [PATCH] PR13858 - Can't do displaced stepping with no symbols Running break-interp.exp with the target always in non-stop mode trips on PR13858, as enabling non-stop also enables displaced stepping. The problem is that when GDB doesn't know where the entry point is, it doesn't know where to put the displaced stepping scratch pad. The test added by this commit exercises this. Without the fix, we get: (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: break *$pc set displaced-stepping on (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: set displaced-stepping on stepi 0x00000000004005be in ?? () Entry point address is not known. (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: stepi p /x $pc $2 = 0x4005be (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: get after PC FAIL: gdb.base/step-over-no-symbols.exp: displaced=on: advanced The fix switches all GNU/Linux ports to get the entry point from AT_ENTRY in the target auxiliary vector instead of from symbols. This is currently only done by PPC when Cell debugging is enabled, but I think all archs should be able to do the same. Note that ppc_linux_displaced_step_location cached the result, I'm guessing to avoid constantly re-fetching the auxv out of remote targets, but that's no longer necessary nowadays, as the auxv blob is itself cached in the inferior object. The ppc_linux_entry_point_addr global is obviously bad for multi-process too nowadays. Tested on x86-64 (-m64/-m32), PPC64 (-m64/-m32) and S/390 GNU/Linux. gdb/ChangeLog: 2015-04-09 Pedro Alves PR gdb/13858 * amd64-linux-tdep.c (amd64_linux_init_abi_common): Install linux_displaced_step_location as gdbarch_displaced_step_location hook. * arm-linux-tdep.c (arm_linux_init_abi): Likewise. * i386-linux-tdep.c (i386_linux_init_abi): Likewise. * linux-tdep.c (linux_displaced_step_location): New function, based on ppc_linux_displaced_step_location. * linux-tdep.h (linux_displaced_step_location): New declaration. * ppc-linux-tdep.c (ppc_linux_entry_point_addr): Delete. (ppc_linux_inferior_created, ppc_linux_displaced_step_location): Delete. (ppc_linux_init_abi): Install linux_displaced_step_location as gdbarch_displaced_step_location hook, even without Cell/B.E.. (_initialize_ppc_linux_tdep): Don't install ppc_linux_inferior_created as inferior_created observer. * s390-linux-tdep.c (s390_gdbarch_init): Install linux_displaced_step_location as gdbarch_displaced_step_location hook. gdb/testsuite/ 2015-04-09 Pedro Alves PR gdb/13858 * gdb.base/step-over-no-symbols.exp: New file. --- gdb/amd64-linux-tdep.c | 2 +- gdb/arm-linux-tdep.c | 2 +- gdb/i386-linux-tdep.c | 2 +- gdb/linux-tdep.c | 26 ++++++++ gdb/linux-tdep.h | 5 ++ gdb/ppc-linux-tdep.c | 52 +-------------- gdb/s390-linux-tdep.c | 3 +- gdb/testsuite/gdb.base/step-over-no-symbols.exp | 87 +++++++++++++++++++++++++ 8 files changed, 125 insertions(+), 54 deletions(-) create mode 100644 gdb/testsuite/gdb.base/step-over-no-symbols.exp diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c index b126366..2a8de82 100644 --- a/gdb/amd64-linux-tdep.c +++ b/gdb/amd64-linux-tdep.c @@ -1833,7 +1833,7 @@ amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch) set_gdbarch_displaced_step_free_closure (gdbarch, simple_displaced_step_free_closure); set_gdbarch_displaced_step_location (gdbarch, - displaced_step_at_entry_point); + linux_displaced_step_location); set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type); diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c index 2b5aed7..f58da84 100644 --- a/gdb/arm-linux-tdep.c +++ b/gdb/arm-linux-tdep.c @@ -1448,7 +1448,7 @@ arm_linux_init_abi (struct gdbarch_info info, set_gdbarch_displaced_step_fixup (gdbarch, arm_displaced_step_fixup); set_gdbarch_displaced_step_free_closure (gdbarch, simple_displaced_step_free_closure); - set_gdbarch_displaced_step_location (gdbarch, displaced_step_at_entry_point); + set_gdbarch_displaced_step_location (gdbarch, linux_displaced_step_location); /* Reversible debugging, process record. */ set_gdbarch_process_record (gdbarch, arm_process_record); diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c index 4a0ce60..061ad3a 100644 --- a/gdb/i386-linux-tdep.c +++ b/gdb/i386-linux-tdep.c @@ -990,7 +990,7 @@ i386_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) set_gdbarch_displaced_step_free_closure (gdbarch, simple_displaced_step_free_closure); set_gdbarch_displaced_step_location (gdbarch, - displaced_step_at_entry_point); + linux_displaced_step_location); /* Functions for 'catch syscall'. */ set_xml_syscall_file_name (gdbarch, XML_SYSCALL_FILENAME_I386); diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c index 0b11e58..7a917f4 100644 --- a/gdb/linux-tdep.c +++ b/gdb/linux-tdep.c @@ -2348,6 +2348,32 @@ linux_infcall_mmap (CORE_ADDR size, unsigned prot) return retval; } +/* See linux-tdep.h. */ + +CORE_ADDR +linux_displaced_step_location (struct gdbarch *gdbarch) +{ + CORE_ADDR addr; + int bp_len; + + /* Determine entry point from target auxiliary vector. */ + if (target_auxv_search (¤t_target, AT_ENTRY, &addr) <= 0) + error (_("Cannot find AT_ENTRY auxiliary vector entry.")); + + /* Make certain that the address points at real code, and not a + function descriptor. */ + addr = gdbarch_convert_from_func_ptr_addr (gdbarch, addr, + ¤t_target); + + /* Inferior calls also use the entry point as a breakpoint location. + We don't want displaced stepping to interfere with those + breakpoints, so leave space. */ + gdbarch_breakpoint_from_pc (gdbarch, &addr, &bp_len); + addr += bp_len * 2; + + return addr; +} + /* Display whether the gcore command is using the /proc/PID/coredump_filter file. */ diff --git a/gdb/linux-tdep.h b/gdb/linux-tdep.h index 78fc36b..ff45286 100644 --- a/gdb/linux-tdep.h +++ b/gdb/linux-tdep.h @@ -37,6 +37,11 @@ extern enum gdb_signal linux_gdb_signal_from_target (struct gdbarch *gdbarch, extern int linux_gdb_signal_to_target (struct gdbarch *gdbarch, enum gdb_signal signal); +/* Default GNU/Linux implementation of `displaced_step_location', as + defined in gdbarch.h. Determines the entry point from AT_ENTRY in + the target auxiliary vector. */ +extern CORE_ADDR linux_displaced_step_location (struct gdbarch *gdbarch); + extern void linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch); extern int linux_is_uclinux (void); diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c index 3afbff2..3849ca6 100644 --- a/gdb/ppc-linux-tdep.c +++ b/gdb/ppc-linux-tdep.c @@ -703,47 +703,6 @@ static struct tramp_frame ppc64_linux_sighandler_tramp_frame = { ppc64_linux_sighandler_cache_init }; - -/* Address to use for displaced stepping. When debugging a stand-alone - SPU executable, entry_point_address () will point to an SPU local-store - address and is thus not usable as displaced stepping location. We use - the auxiliary vector to determine the PowerPC-side entry point address - instead. */ - -static CORE_ADDR ppc_linux_entry_point_addr = 0; - -static void -ppc_linux_inferior_created (struct target_ops *target, int from_tty) -{ - ppc_linux_entry_point_addr = 0; -} - -static CORE_ADDR -ppc_linux_displaced_step_location (struct gdbarch *gdbarch) -{ - if (ppc_linux_entry_point_addr == 0) - { - CORE_ADDR addr; - - /* Determine entry point from target auxiliary vector. */ - if (target_auxv_search (¤t_target, AT_ENTRY, &addr) <= 0) - error (_("Cannot find AT_ENTRY auxiliary vector entry.")); - - /* Make certain that the address points at real code, and not a - function descriptor. */ - addr = gdbarch_convert_from_func_ptr_addr (gdbarch, addr, - ¤t_target); - - /* Inferior calls also use the entry point as a breakpoint location. - We don't want displaced stepping to interfere with those - breakpoints, so leave space. */ - ppc_linux_entry_point_addr = addr + 2 * PPC_INSN_SIZE; - } - - return ppc_linux_entry_point_addr; -} - - /* Return 1 if PPC_ORIG_R3_REGNUM and PPC_TRAP_REGNUM are usable. */ int ppc_linux_trap_reg_p (struct gdbarch *gdbarch) @@ -1837,13 +1796,11 @@ ppc_linux_init_abi (struct gdbarch_info info, /* Cell/B.E. cross-architecture unwinder support. */ frame_unwind_prepend_unwinder (gdbarch, &ppu2spu_unwind); - - /* The default displaced_step_at_entry_point doesn't work for - SPU stand-alone executables. */ - set_gdbarch_displaced_step_location (gdbarch, - ppc_linux_displaced_step_location); } + set_gdbarch_displaced_step_location (gdbarch, + linux_displaced_step_location); + set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type); /* Support reverse debugging. */ @@ -1870,9 +1827,6 @@ _initialize_ppc_linux_tdep (void) gdbarch_register_osabi (bfd_arch_rs6000, bfd_mach_rs6k, GDB_OSABI_LINUX, ppc_linux_init_abi); - /* Attach to inferior_created observer. */ - observer_attach_inferior_created (ppc_linux_inferior_created); - /* Attach to observers to track __spe_current_active_context. */ observer_attach_inferior_created (ppc_linux_spe_context_inferior_created); observer_attach_solib_loaded (ppc_linux_spe_context_solib_loaded); diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c index cafa57b..b83a264 100644 --- a/gdb/s390-linux-tdep.c +++ b/gdb/s390-linux-tdep.c @@ -3295,8 +3295,7 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_displaced_step_fixup (gdbarch, s390_displaced_step_fixup); set_gdbarch_displaced_step_free_closure (gdbarch, simple_displaced_step_free_closure); - set_gdbarch_displaced_step_location (gdbarch, - displaced_step_at_entry_point); + set_gdbarch_displaced_step_location (gdbarch, linux_displaced_step_location); set_gdbarch_max_insn_length (gdbarch, S390_MAX_INSTR_SIZE); /* Note that GNU/Linux is the only OS supported on this diff --git a/gdb/testsuite/gdb.base/step-over-no-symbols.exp b/gdb/testsuite/gdb.base/step-over-no-symbols.exp new file mode 100644 index 0000000..0880d66 --- /dev/null +++ b/gdb/testsuite/gdb.base/step-over-no-symbols.exp @@ -0,0 +1,87 @@ +# Copyright (C) 2015 Free Software Foundation, Inc. + +# This program 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 3 of the License, or +# (at your option) any later version. +# +# This program 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 this program. If not, see . + +# Test that GDB can step past a breakpoint even if GDB doesn't have +# symbols for the main binary. + +standard_testfile start.c + +if { [build_executable "failed to build" ${testfile} $srcfile] } { + return -1 +} + +# Get the current PC. MSG is used as test message. + +proc get_pc { msg } { + global hex gdb_prompt + + set addr "" + gdb_test_multiple "p /x \$pc" "$msg" { + -re " = ($hex).*$gdb_prompt $" { + set addr $expect_out(1,string) + pass "$msg" + } + } + + return $addr +} + +# Test stepping past a breakpoint with no symbols. DISPLACED is one +# of the "set displaced-stepping" options. GDB should be able to fall +# back to stepping past the breakpoint using an in-line step-over. + +proc test_step_over { displaced } { + global hex + global binfile + + clean_restart $binfile + + if ![runto_main] { + fail "couldn't run to main" + untested "stepping over breakpoint with displaced=$displaced" + return -1 + } + + delete_breakpoints + + set msg "purging symbols" + gdb_test_multiple "symbol-file" "$msg" { + -re "Discard symbol table.*y or n. $" { + gdb_test "y" "No symbol file now." "$msg" + } + } + + set before_addr [get_pc "get before PC"] + + gdb_test "break *\$pc" "Breakpoint .* at $hex" + + gdb_test_no_output "set displaced-stepping $displaced" + + gdb_test "stepi" "$hex in \?\? .*" + + set after_addr [get_pc "get after PC"] + + gdb_assert {$before_addr != $after_addr} "advanced" +} + +foreach displaced { "off" "on" "auto" } { + if { $displaced != "off" && ![support_displaced_stepping] } { + continue + } + + with_test_prefix "displaced=$displaced" { + test_step_over $displaced + } +}