diff options
Diffstat (limited to 'gdb/infrun.c')
| -rw-r--r-- | gdb/infrun.c | 451 |
1 files changed, 280 insertions, 171 deletions
diff --git a/gdb/infrun.c b/gdb/infrun.c index 1527ed9..a46587e 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -176,15 +176,53 @@ static int use_thread_step_needed = USE_THREAD_STEP_NEEDED; #define DYNAMIC_TRAMPOLINE_NEXTPC(pc) 0 #endif -/* On SVR4 based systems, determining the callee's address is exceedingly - difficult and depends on the implementation of the run time loader. - If we are stepping at the source level, we single step until we exit - the run time loader code and reach the callee's address. */ +/* If the program uses ELF-style shared libraries, then calls to + functions in shared libraries go through stubs, which live in a + table called the PLT (Procedure Linkage Table). The first time the + function is called, the stub sends control to the dynamic linker, + which looks up the function's real address, patches the stub so + that future calls will go directly to the function, and then passes + control to the function. + + If we are stepping at the source level, we don't want to see any of + this --- we just want to skip over the stub and the dynamic linker. + The simple approach is to single-step until control leaves the + dynamic linker. + + However, on some systems (e.g., Red Hat Linux 5.2) the dynamic + linker calls functions in the shared C library, so you can't tell + from the PC alone whether the dynamic linker is still running. In + this case, we use a step-resume breakpoint to get us past the + dynamic linker, as if we were using "next" to step over a function + call. + + IN_SOLIB_DYNSYM_RESOLVE_CODE says whether we're in the dynamic + linker code or not. Normally, this means we single-step. However, + if SKIP_SOLIB_RESOLVER then returns non-zero, then its value is an + address where we can place a step-resume breakpoint to get past the + linker's symbol resolution function. + + IN_SOLIB_DYNSYM_RESOLVE_CODE can generally be implemented in a + pretty portable way, by comparing the PC against the address ranges + of the dynamic linker's sections. + + SKIP_SOLIB_RESOLVER is generally going to be system-specific, since + it depends on internal details of the dynamic linker. It's usually + not too hard to figure out where to put a breakpoint, but it + certainly isn't portable. SKIP_SOLIB_RESOLVER should do plenty of + sanity checking. If it can't figure things out, returning zero and + getting the (possibly confusing) stepping behavior is better than + signalling an error, which will obscure the change in the + inferior's state. */ #ifndef IN_SOLIB_DYNSYM_RESOLVE_CODE #define IN_SOLIB_DYNSYM_RESOLVE_CODE(pc) 0 #endif +#ifndef SKIP_SOLIB_RESOLVER +#define SKIP_SOLIB_RESOLVER(pc) 0 +#endif + /* For SVR4 shared libraries, each call goes through a small piece of trampoline code in the ".plt" section. IN_SOLIB_CALL_TRAMPOLINE evaluates to nonzero if we are current stopped in one of these. */ @@ -1137,8 +1175,10 @@ void init_execution_control_state (struct execution_control_state * ecs); void handle_inferior_event (struct execution_control_state * ecs); static void check_sigtramp2 (struct execution_control_state *ecs); +static void step_over_function (struct execution_control_state *ecs); static void stop_stepping (struct execution_control_state *ecs); static void prepare_to_wait (struct execution_control_state *ecs); +static void keep_going (struct execution_control_state *ecs); /* Wait for control to return from inferior to debugger. If inferior gets a signal, we may decide to start it up again @@ -2108,15 +2148,17 @@ handle_inferior_event (struct execution_control_state *ecs) { trap_expected = 1; stop_signal = TARGET_SIGNAL_0; - goto keep_going; + keep_going (ecs); + return; } } else if (ecs->ws.kind == TARGET_WAITKIND_VFORKED) { if (ecs->random_signal) /* I.e., no catchpoint triggered for this. */ { - stop_signal = TARGET_SIGNAL_0; - goto keep_going; + stop_signal = TARGET_SIGNAL_0; + keep_going (ecs); + return; } } else if (ecs->ws.kind == TARGET_WAITKIND_EXECD) @@ -2126,7 +2168,8 @@ handle_inferior_event (struct execution_control_state *ecs) { trap_expected = 1; stop_signal = TARGET_SIGNAL_0; - goto keep_going; + keep_going (ecs); + return; } } @@ -2182,7 +2225,7 @@ handle_inferior_event (struct execution_control_state *ecs) that case, when we reach this point, there is already a step-resume breakpoint established, right where it should be: immediately after the function call the user is "next"-ing - over. If we jump to step_over_function now, two bad things + over. If we call step_over_function now, two bad things happen: - we'll create a new breakpoint, at wherever the current @@ -2230,7 +2273,10 @@ handle_inferior_event (struct execution_control_state *ecs) remove_breakpoints (); breakpoints_inserted = 0; if (!GET_LONGJMP_TARGET (&jmp_buf_pc)) - goto keep_going; + { + keep_going (ecs); + return; + } /* Need to blow away step-resume breakpoint, as it interferes with us */ @@ -2256,7 +2302,8 @@ handle_inferior_event (struct execution_control_state *ecs) #endif /* 0 */ set_longjmp_resume_breakpoint (jmp_buf_pc, NULL); ecs->handling_longjmp = 1; /* FIXME */ - goto keep_going; + keep_going (ecs); + return; case BPSTAT_WHAT_CLEAR_LONGJMP_RESUME: case BPSTAT_WHAT_CLEAR_LONGJMP_RESUME_SINGLE: @@ -2269,7 +2316,8 @@ handle_inferior_event (struct execution_control_state *ecs) step_frame_address))) { ecs->another_trap = 1; - goto keep_going; + keep_going (ecs); + return; } #endif /* 0 */ disable_longjmp_breakpoint (); @@ -2452,7 +2500,8 @@ handle_inferior_event (struct execution_control_state *ecs) if (SOLIB_IN_DYNAMIC_LINKER (ecs->pid, stop_pc)) { ecs->another_trap = 1; - goto keep_going; + keep_going (ecs); + return; } #endif /* Else, stop and report the catchpoint(s) whose triggering @@ -2499,7 +2548,8 @@ handle_inferior_event (struct execution_control_state *ecs) /* I'm not sure whether this needs to be check_sigtramp2 or whether it could/should be keep_going. */ check_sigtramp2 (ecs); - goto keep_going; + keep_going (ecs); + return; } if (step_range_end == 0) @@ -2508,7 +2558,8 @@ handle_inferior_event (struct execution_control_state *ecs) /* I'm not sure whether this needs to be check_sigtramp2 or whether it could/should be keep_going. */ check_sigtramp2 (ecs); - goto keep_going; + keep_going (ecs); + return; } /* If stepping through a line, keep going if still within it. @@ -2522,7 +2573,8 @@ handle_inferior_event (struct execution_control_state *ecs) /* We might be doing a BPSTAT_WHAT_SINGLE and getting a signal. So definately need to check for sigtramp here. */ check_sigtramp2 (ecs); - goto keep_going; + keep_going (ecs); + return; } /* We stepped out of the stepping range. */ @@ -2532,7 +2584,27 @@ handle_inferior_event (struct execution_control_state *ecs) until we exit the run time loader code and reach the callee's address. */ if (step_over_calls < 0 && IN_SOLIB_DYNSYM_RESOLVE_CODE (stop_pc)) - goto keep_going; + { + CORE_ADDR pc_after_resolver = SKIP_SOLIB_RESOLVER (stop_pc); + + if (pc_after_resolver) + { + /* Set up a step-resume breakpoint at the address + indicated by SKIP_SOLIB_RESOLVER. */ + struct symtab_and_line sr_sal; + INIT_SAL (&sr_sal); + sr_sal.pc = pc_after_resolver; + + check_for_old_step_resume_breakpoint (); + step_resume_breakpoint = + set_momentary_breakpoint (sr_sal, NULL, bp_step_resume); + if (breakpoints_inserted) + insert_breakpoints (); + } + + keep_going (ecs); + return; + } /* We can't update step_sp every time through the loop, because reading the stack pointer would slow down stepping too much. @@ -2591,7 +2663,7 @@ handle_inferior_event (struct execution_control_state *ecs) /* We just stepped out of a signal handler and into its calling trampoline. - Normally, we'd jump to step_over_function from + Normally, we'd call step_over_function from here, but for some reason GDB can't unwind the stack correctly to find the real PC for the point user code where the signal trampoline will return @@ -2620,7 +2692,8 @@ handle_inferior_event (struct execution_control_state *ecs) step_range_end = (step_range_start = prev_pc) + 1; ecs->remove_breakpoints_on_following_step = 1; - goto keep_going; + keep_going (ecs); + return; } if (stop_pc == ecs->stop_func_start /* Quick test */ @@ -2642,8 +2715,12 @@ handle_inferior_event (struct execution_control_state *ecs) } if (step_over_calls > 0 || IGNORE_HELPER_CALL (stop_pc)) - /* We're doing a "next". */ - goto step_over_function; + { + /* We're doing a "next". */ + step_over_function (ecs); + keep_going (ecs); + return; + } /* If we are in a function call trampoline (a stub between the calling routine and the real function), locate the real @@ -2668,7 +2745,8 @@ handle_inferior_event (struct execution_control_state *ecs) step_resume_breakpoint = set_momentary_breakpoint (xxx, NULL, bp_step_resume); insert_breakpoints (); - goto keep_going; + keep_going (ecs); + return; } } @@ -2685,40 +2763,9 @@ handle_inferior_event (struct execution_control_state *ecs) if (tmp_sal.line != 0) goto step_into_function; } - - step_over_function: - /* A subroutine call has happened. */ - { - /* We've just entered a callee, and we wish to resume until it - returns to the caller. Setting a step_resume breakpoint on - the return address will catch a return from the callee. - - However, if the callee is recursing, we want to be careful - not to catch returns of those recursive calls, but only of - THIS instance of the call. - - To do this, we set the step_resume bp's frame to our current - caller's frame (step_frame_address, which is set by the "next" - or "until" command, before execution begins). */ - struct symtab_and_line sr_sal; - - INIT_SAL (&sr_sal); /* initialize to zeros */ - sr_sal.pc = - ADDR_BITS_REMOVE (SAVED_PC_AFTER_CALL (get_current_frame ())); - sr_sal.section = find_pc_overlay (sr_sal.pc); - - check_for_old_step_resume_breakpoint (); - step_resume_breakpoint = - set_momentary_breakpoint (sr_sal, get_current_frame (), - bp_step_resume); - - if (!IN_SOLIB_DYNSYM_RESOLVE_CODE (sr_sal.pc)) - step_resume_breakpoint->frame = step_frame_address; - - if (breakpoints_inserted) - insert_breakpoints (); - } - goto keep_going; + step_over_function (ecs); + keep_going (ecs); + return; step_into_function: /* Subroutine call with source code we should not step over. @@ -2772,7 +2819,8 @@ handle_inferior_event (struct execution_control_state *ecs) /* And make sure stepping stops right away then. */ step_range_end = step_range_start; } - goto keep_going; + keep_going (ecs); + return; } /* We've wandered out of the step range. */ @@ -2817,7 +2865,8 @@ handle_inferior_event (struct execution_control_state *ecs) /* Restart without fiddling with the step ranges or other state. */ - goto keep_going; + keep_going (ecs); + return; } } @@ -2877,121 +2926,9 @@ handle_inferior_event (struct execution_control_state *ecs) step_frame_address = current_frame; } - keep_going: - /* Come to this label when you need to resume the inferior. - It's really much cleaner to do a goto than a maze of if-else - conditions. */ - - /* ??rehrauer: ttrace on HP-UX theoretically allows one to debug - a vforked child beetween its creation and subsequent exit or - call to exec(). However, I had big problems in this rather - creaky exec engine, getting that to work. The fundamental - problem is that I'm trying to debug two processes via an - engine that only understands a single process with possibly - multiple threads. - - Hence, this spot is known to have problems when - target_can_follow_vfork_prior_to_exec returns 1. */ - - /* Save the pc before execution, to compare with pc after stop. */ - prev_pc = read_pc (); /* Might have been DECR_AFTER_BREAK */ - prev_func_start = ecs->stop_func_start; /* Ok, since if DECR_PC_AFTER - BREAK is defined, the - original pc would not have - been at the start of a - function. */ - prev_func_name = ecs->stop_func_name; - - if (ecs->update_step_sp) - step_sp = read_sp (); - ecs->update_step_sp = 0; - - /* If we did not do break;, it means we should keep - running the inferior and not return to debugger. */ - - if (trap_expected && stop_signal != TARGET_SIGNAL_TRAP) - { - /* We took a signal (which we are supposed to pass through to - the inferior, else we'd have done a break above) and we - haven't yet gotten our trap. Simply continue. */ - resume (currently_stepping (ecs), stop_signal); - } - else - { - /* Either the trap was not expected, but we are continuing - anyway (the user asked that this signal be passed to the - child) - -- or -- - The signal was SIGTRAP, e.g. it was our signal, but we - decided we should resume from it. - - We're going to run this baby now! - - Insert breakpoints now, unless we are trying - to one-proceed past a breakpoint. */ - /* If we've just finished a special step resume and we don't - want to hit a breakpoint, pull em out. */ - if (step_resume_breakpoint == NULL - && through_sigtramp_breakpoint == NULL - && ecs->remove_breakpoints_on_following_step) - { - ecs->remove_breakpoints_on_following_step = 0; - remove_breakpoints (); - breakpoints_inserted = 0; - } - else if (!breakpoints_inserted && - (through_sigtramp_breakpoint != NULL || !ecs->another_trap)) - { - breakpoints_failed = insert_breakpoints (); - if (breakpoints_failed) - { - stop_stepping (ecs); - return; - } - breakpoints_inserted = 1; - } - - trap_expected = ecs->another_trap; - - /* Do not deliver SIGNAL_TRAP (except when the user - explicitly specifies that such a signal should be - delivered to the target program). - - Typically, this would occure when a user is debugging a - target monitor on a simulator: the target monitor sets a - breakpoint; the simulator encounters this break-point and - halts the simulation handing control to GDB; GDB, noteing - that the break-point isn't valid, returns control back to - the simulator; the simulator then delivers the hardware - equivalent of a SIGNAL_TRAP to the program being - debugged. */ - - if (stop_signal == TARGET_SIGNAL_TRAP - && !signal_program[stop_signal]) - stop_signal = TARGET_SIGNAL_0; - -#ifdef SHIFT_INST_REGS - /* I'm not sure when this following segment applies. I do know, - now, that we shouldn't rewrite the regs when we were stopped - by a random signal from the inferior process. */ - /* FIXME: Shouldn't this be based on the valid bit of the SXIP? - (this is only used on the 88k). */ - - if (!bpstat_explains_signal (stop_bpstat) - && (stop_signal != TARGET_SIGNAL_CHLD) - && !stopped_by_random_signal) - SHIFT_INST_REGS (); -#endif /* SHIFT_INST_REGS */ - - resume (currently_stepping (ecs), stop_signal); - } - - prepare_to_wait (ecs); - return; + keep_going (ecs); } /* extra brace, to preserve old indentation */ - - stop_stepping (ecs); } /* Are we in the middle of stepping? */ @@ -3043,6 +2980,39 @@ check_sigtramp2 (struct execution_control_state *ecs) } } + +/* We've just entered a callee, and we wish to resume until it returns + to the caller. Setting a step_resume breakpoint on the return + address will catch a return from the callee. + + However, if the callee is recursing, we want to be careful not to + catch returns of those recursive calls, but only of THIS instance + of the call. + + To do this, we set the step_resume bp's frame to our current + caller's frame (step_frame_address, which is set by the "next" or + "until" command, before execution begins). */ + +static void +step_over_function (struct execution_control_state *ecs) +{ + struct symtab_and_line sr_sal; + + INIT_SAL (&sr_sal); /* initialize to zeros */ + sr_sal.pc = ADDR_BITS_REMOVE (SAVED_PC_AFTER_CALL (get_current_frame ())); + sr_sal.section = find_pc_overlay (sr_sal.pc); + + check_for_old_step_resume_breakpoint (); + step_resume_breakpoint = + set_momentary_breakpoint (sr_sal, get_current_frame (), bp_step_resume); + + if (!IN_SOLIB_DYNSYM_RESOLVE_CODE (sr_sal.pc)) + step_resume_breakpoint->frame = step_frame_address; + + if (breakpoints_inserted) + insert_breakpoints (); +} + static void stop_stepping (struct execution_control_state *ecs) { @@ -3084,6 +3054,118 @@ stop_stepping (struct execution_control_state *ecs) ecs->wait_some_more = 0; } +/* This function handles various cases where we need to continue + waiting for the inferior. */ +/* (Used to be the keep_going: label in the old wait_for_inferior) */ + +static void +keep_going (struct execution_control_state *ecs) +{ + /* ??rehrauer: ttrace on HP-UX theoretically allows one to debug a + vforked child between its creation and subsequent exit or call to + exec(). However, I had big problems in this rather creaky exec + engine, getting that to work. The fundamental problem is that + I'm trying to debug two processes via an engine that only + understands a single process with possibly multiple threads. + + Hence, this spot is known to have problems when + target_can_follow_vfork_prior_to_exec returns 1. */ + + /* Save the pc before execution, to compare with pc after stop. */ + prev_pc = read_pc (); /* Might have been DECR_AFTER_BREAK */ + prev_func_start = ecs->stop_func_start; /* Ok, since if DECR_PC_AFTER + BREAK is defined, the + original pc would not have + been at the start of a + function. */ + prev_func_name = ecs->stop_func_name; + + if (ecs->update_step_sp) + step_sp = read_sp (); + ecs->update_step_sp = 0; + + /* If we did not do break;, it means we should keep running the + inferior and not return to debugger. */ + + if (trap_expected && stop_signal != TARGET_SIGNAL_TRAP) + { + /* We took a signal (which we are supposed to pass through to + the inferior, else we'd have done a break above) and we + haven't yet gotten our trap. Simply continue. */ + resume (currently_stepping (ecs), stop_signal); + } + else + { + /* Either the trap was not expected, but we are continuing + anyway (the user asked that this signal be passed to the + child) + -- or -- + The signal was SIGTRAP, e.g. it was our signal, but we + decided we should resume from it. + + We're going to run this baby now! + + Insert breakpoints now, unless we are trying to one-proceed + past a breakpoint. */ + /* If we've just finished a special step resume and we don't + want to hit a breakpoint, pull em out. */ + if (step_resume_breakpoint == NULL + && through_sigtramp_breakpoint == NULL + && ecs->remove_breakpoints_on_following_step) + { + ecs->remove_breakpoints_on_following_step = 0; + remove_breakpoints (); + breakpoints_inserted = 0; + } + else if (!breakpoints_inserted && + (through_sigtramp_breakpoint != NULL || !ecs->another_trap)) + { + breakpoints_failed = insert_breakpoints (); + if (breakpoints_failed) + { + stop_stepping (ecs); + return; + } + breakpoints_inserted = 1; + } + + trap_expected = ecs->another_trap; + + /* Do not deliver SIGNAL_TRAP (except when the user explicitly + specifies that such a signal should be delivered to the + target program). + + Typically, this would occure when a user is debugging a + target monitor on a simulator: the target monitor sets a + breakpoint; the simulator encounters this break-point and + halts the simulation handing control to GDB; GDB, noteing + that the break-point isn't valid, returns control back to the + simulator; the simulator then delivers the hardware + equivalent of a SIGNAL_TRAP to the program being debugged. */ + + if (stop_signal == TARGET_SIGNAL_TRAP + && !signal_program[stop_signal]) + stop_signal = TARGET_SIGNAL_0; + +#ifdef SHIFT_INST_REGS + /* I'm not sure when this following segment applies. I do know, + now, that we shouldn't rewrite the regs when we were stopped + by a random signal from the inferior process. */ + /* FIXME: Shouldn't this be based on the valid bit of the SXIP? + (this is only used on the 88k). */ + + if (!bpstat_explains_signal (stop_bpstat) + && (stop_signal != TARGET_SIGNAL_CHLD) + && !stopped_by_random_signal) + SHIFT_INST_REGS (); +#endif /* SHIFT_INST_REGS */ + + resume (currently_stepping (ecs), stop_signal); + } + + prepare_to_wait (ecs); +} + /* This function normally comes after a resume, before handle_inferior_event exits. It takes care of any last bits of housekeeping, and sets the all-important wait_some_more flag. */ @@ -3365,6 +3447,33 @@ signal_pass_state (int signo) return signal_program[signo]; } +int signal_stop_update (signo, state) + int signo; + int state; +{ + int ret = signal_stop[signo]; + signal_stop[signo] = state; + return ret; +} + +int signal_print_update (signo, state) + int signo; + int state; +{ + int ret = signal_print[signo]; + signal_print[signo] = state; + return ret; +} + +int signal_pass_update (signo, state) + int signo; + int state; +{ + int ret = signal_program[signo]; + signal_program[signo] = state; + return ret; +} + static void sig_print_header (void) { |