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binutils-gdb/gdb/x86-tdep.h

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infrun: step through indirect branch thunks With version 7.3 GCC supports new options -mindirect-branch=<choice> -mfunction-return=<choice> The choices are: keep behaves as before thunk jumps through a thunk thunk-external jumps through an external thunk thunk-inline jumps through an inlined thunk For thunk and thunk-external, GDB would, on a call to the thunk, step into the thunk and then resume to its caller assuming that this is an undebuggable function. On a return thunk, GDB would stop inside the thunk. Make GDB step through such thunks instead. Before: Temporary breakpoint 1, main () at gdb.base/step-indirect-call-thunk.c:37 37 x = apply (inc, 41); (gdb) s apply (op=0x80483e6 <inc>, x=41) at gdb.base/step-indirect-call-thunk.c:29 29 return op (x); (gdb) 30 } After: Temporary breakpoint 1, main () at gdb.base/step-indirect-call-thunk.c:37 37 x = apply (inc, 41); (gdb) s apply (op=0x80483e6 <inc>, x=41) at gdb.base/step-indirect-call-thunk.c:29 29 return op (x); (gdb) inc (x=41) at gdb.base/step-indirect-call-thunk.c:23 23 return x + 1; This is independent of the step-mode. In order to step into the thunk, you would need to use stepi. When stepping over an indirect call thunk, GDB would first step through the thunk, then recognize that it stepped into a sub-routine and resume to the caller (of the thunk). Not sure whether this is worth optimizing. Thunk detection is implemented via gdbarch. I implemented the methods for IA. Other architectures may run into unexpected fails. The tests assume a fixed number of instruction steps to reach a thunk. This depends on the compiler as well as the architecture. They may need adjustments when we add support for more architectures. Or we can simply drop those tests that cover being able to step into thunks using instruction stepping. When using an older GCC, the tests will fail to build and will be reported as untested: Running .../gdb.base/step-indirect-call-thunk.exp ... gdb compile failed, \ gcc: error: unrecognized command line option '-mindirect-branch=thunk' gcc: error: unrecognized command line option '-mfunction-return=thunk' === gdb Summary === # of untested testcases 1 gdb/ * infrun.c (process_event_stop_test): Call gdbarch_in_indirect_branch_thunk. * gdbarch.sh (in_indirect_branch_thunk): New. * gdbarch.c: Regenerated. * gdbarch.h: Regenerated. * x86-tdep.h: New. * x86-tdep.c: New. * Makefile.in (ALL_TARGET_OBS): Add x86-tdep.o. (HFILES_NO_SRCDIR): Add x86-tdep.h. (ALLDEPFILES): Add x86-tdep.c. * arch-utils.h (default_in_indirect_branch_thunk): New. * arch-utils.c (default_in_indirect_branch_thunk): New. * i386-tdep: Include x86-tdep.h. (i386_in_indirect_branch_thunk): New. (i386_elf_init_abi): Set in_indirect_branch_thunk gdbarch function. * amd64-tdep: Include x86-tdep.h. (amd64_in_indirect_branch_thunk): New. (amd64_init_abi): Set in_indirect_branch_thunk gdbarch function. testsuite/ * gdb.base/step-indirect-call-thunk.exp: New. * gdb.base/step-indirect-call-thunk.c: New. * gdb.reverse/step-indirect-call-thunk.exp: New. * gdb.reverse/step-indirect-call-thunk.c: New.
2018-02-14 21:30:57 +08:00
/* Target-dependent code for X86-based targets.
Update copyright year range in all GDB files. This commit applies all changes made after running the gdb/copyright.py script. Note that one file was flagged by the script, due to an invalid copyright header (gdb/unittests/basic_string_view/element_access/char/empty.cc). As the file was copied from GCC's libstdc++-v3 testsuite, this commit leaves this file untouched for the time being; a patch to fix the header was sent to gcc-patches first. gdb/ChangeLog: Update copyright year range in all GDB files.
2019-01-01 14:01:51 +08:00
Copyright (C) 2018-2019 Free Software Foundation, Inc.
infrun: step through indirect branch thunks With version 7.3 GCC supports new options -mindirect-branch=<choice> -mfunction-return=<choice> The choices are: keep behaves as before thunk jumps through a thunk thunk-external jumps through an external thunk thunk-inline jumps through an inlined thunk For thunk and thunk-external, GDB would, on a call to the thunk, step into the thunk and then resume to its caller assuming that this is an undebuggable function. On a return thunk, GDB would stop inside the thunk. Make GDB step through such thunks instead. Before: Temporary breakpoint 1, main () at gdb.base/step-indirect-call-thunk.c:37 37 x = apply (inc, 41); (gdb) s apply (op=0x80483e6 <inc>, x=41) at gdb.base/step-indirect-call-thunk.c:29 29 return op (x); (gdb) 30 } After: Temporary breakpoint 1, main () at gdb.base/step-indirect-call-thunk.c:37 37 x = apply (inc, 41); (gdb) s apply (op=0x80483e6 <inc>, x=41) at gdb.base/step-indirect-call-thunk.c:29 29 return op (x); (gdb) inc (x=41) at gdb.base/step-indirect-call-thunk.c:23 23 return x + 1; This is independent of the step-mode. In order to step into the thunk, you would need to use stepi. When stepping over an indirect call thunk, GDB would first step through the thunk, then recognize that it stepped into a sub-routine and resume to the caller (of the thunk). Not sure whether this is worth optimizing. Thunk detection is implemented via gdbarch. I implemented the methods for IA. Other architectures may run into unexpected fails. The tests assume a fixed number of instruction steps to reach a thunk. This depends on the compiler as well as the architecture. They may need adjustments when we add support for more architectures. Or we can simply drop those tests that cover being able to step into thunks using instruction stepping. When using an older GCC, the tests will fail to build and will be reported as untested: Running .../gdb.base/step-indirect-call-thunk.exp ... gdb compile failed, \ gcc: error: unrecognized command line option '-mindirect-branch=thunk' gcc: error: unrecognized command line option '-mfunction-return=thunk' === gdb Summary === # of untested testcases 1 gdb/ * infrun.c (process_event_stop_test): Call gdbarch_in_indirect_branch_thunk. * gdbarch.sh (in_indirect_branch_thunk): New. * gdbarch.c: Regenerated. * gdbarch.h: Regenerated. * x86-tdep.h: New. * x86-tdep.c: New. * Makefile.in (ALL_TARGET_OBS): Add x86-tdep.o. (HFILES_NO_SRCDIR): Add x86-tdep.h. (ALLDEPFILES): Add x86-tdep.c. * arch-utils.h (default_in_indirect_branch_thunk): New. * arch-utils.c (default_in_indirect_branch_thunk): New. * i386-tdep: Include x86-tdep.h. (i386_in_indirect_branch_thunk): New. (i386_elf_init_abi): Set in_indirect_branch_thunk gdbarch function. * amd64-tdep: Include x86-tdep.h. (amd64_in_indirect_branch_thunk): New. (amd64_init_abi): Set in_indirect_branch_thunk gdbarch function. testsuite/ * gdb.base/step-indirect-call-thunk.exp: New. * gdb.base/step-indirect-call-thunk.c: New. * gdb.reverse/step-indirect-call-thunk.exp: New. * gdb.reverse/step-indirect-call-thunk.c: New.
2018-02-14 21:30:57 +08:00
This file is part of GDB.
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 <http://www.gnu.org/licenses/>. */
#ifndef X86_TDEP_H
#define X86_TDEP_H
/* Checks whether PC lies in an indirect branch thunk using registers
REGISTER_NAMES[LO] (inclusive) to REGISTER_NAMES[HI] (exclusive). */
extern bool x86_in_indirect_branch_thunk (CORE_ADDR pc,
const char **register_names,
int lo, int hi);
#endif /* x86-tdep.h */
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