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author | Tom de Vries <tdevries@suse.de> | 2023-11-28 10:31:25 +0100 |
---|---|---|
committer | Tom de Vries <tdevries@suse.de> | 2023-11-28 10:31:25 +0100 |
commit | f9582a22dba747ff0905f4c1a80d84f677eeb928 (patch) | |
tree | 042f98562a1dc37eb3a6e964f65afb4e942fd138 /gdb/breakpoint.c | |
parent | 31477859c0c2a9b79a649be98830afebb9aa1d46 (diff) | |
download | fsf-binutils-gdb-f9582a22dba747ff0905f4c1a80d84f677eeb928.zip fsf-binutils-gdb-f9582a22dba747ff0905f4c1a80d84f677eeb928.tar.gz fsf-binutils-gdb-f9582a22dba747ff0905f4c1a80d84f677eeb928.tar.bz2 |
[gdb] Fix segfault in for_each_block, part 1
When running test-case gdb.base/vfork-follow-parent.exp on powerpc64 (likewise
on s390x), I run into:
...
(gdb) PASS: gdb.base/vfork-follow-parent.exp: \
exec_file=vfork-follow-parent-exit: target-non-stop=on: non-stop=off: \
resolution_method=schedule-multiple: print unblock_parent = 1
continue^M
Continuing.^M
Reading symbols from vfork-follow-parent-exit...^M
^M
^M
Fatal signal: Segmentation fault^M
----- Backtrace -----^M
0x1027d3e7 gdb_internal_backtrace_1^M
src/gdb/bt-utils.c:122^M
0x1027d54f _Z22gdb_internal_backtracev^M
src/gdb/bt-utils.c:168^M
0x1057643f handle_fatal_signal^M
src/gdb/event-top.c:889^M
0x10576677 handle_sigsegv^M
src/gdb/event-top.c:962^M
0x3fffa7610477 ???^M
0x103f2144 for_each_block^M
src/gdb/dcache.c:199^M
0x103f235b _Z17dcache_invalidateP13dcache_struct^M
src/gdb/dcache.c:251^M
0x10bde8c7 _Z24target_dcache_invalidatev^M
src/gdb/target-dcache.c:50^M
...
or similar.
The root cause for the segmentation fault is that linux_is_uclinux gives an
incorrect result: it should always return false, given that we're running on a
regular linux system, but instead it returns first true, then false.
In more detail, the segmentation fault happens as follows:
- a program space with an address space is created
- a second program space is about to be created. maybe_new_address_space
is called, and because linux_is_uclinux returns true, maybe_new_address_space
returns false, and no new address space is created
- a second program space with the same address space is created
- a program space is deleted. Because linux_is_uclinux now returns false,
gdbarch_has_shared_address_space (current_inferior ()->arch ()) returns
false, and the address space is deleted
- when gdb uses the address space of the remaining program space, we run into
the segfault, because the address space is deleted.
Hardcoding linux_is_uclinux to false makes the test-case pass.
We leave addressing the root cause for the following commit in this series.
For now, prevent the segmentation fault by making the address space a refcounted
object.
This was already suggested here [1]:
...
A better solution might be to have the address spaces be reference counted
...
Tested on top of trunk on x86_64-linux and ppc64le-linux.
Tested on top of gdb-14-branch on ppc64-linux.
Co-Authored-By: Simon Marchi <simon.marchi@polymtl.ca>
PR gdb/30547
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30547
[1] https://sourceware.org/pipermail/gdb-patches/2023-October/202928.html
Diffstat (limited to 'gdb/breakpoint.c')
-rw-r--r-- | gdb/breakpoint.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index af395fd..699919e 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -1723,7 +1723,7 @@ one_breakpoint_xfer_memory (gdb_byte *readbuf, gdb_byte *writebuf, int bptoffset = 0; if (!breakpoint_address_match (target_info->placed_address_space, 0, - current_program_space->aspace, 0)) + current_program_space->aspace.get (), 0)) { /* The breakpoint is inserted in a different address space. */ return; @@ -2409,7 +2409,7 @@ should_be_inserted (struct bp_location *bl) a breakpoint. */ if ((bl->loc_type == bp_loc_software_breakpoint || bl->loc_type == bp_loc_hardware_breakpoint) - && stepping_past_instruction_at (bl->pspace->aspace, + && stepping_past_instruction_at (bl->pspace->aspace.get (), bl->address) /* The single-step breakpoint may be inserted at the location we're trying to step if the instruction branches to itself. @@ -2847,7 +2847,7 @@ insert_bp_location (struct bp_location *bl, read the breakpoint instead of returning the data saved in the breakpoint location's shadow contents. */ bl->target_info.reqstd_address = bl->address; - bl->target_info.placed_address_space = bl->pspace->aspace; + bl->target_info.placed_address_space = bl->pspace->aspace.get (); bl->target_info.length = bl->length; /* When working with target-side conditions, we must pass all the conditions @@ -4429,7 +4429,7 @@ bp_location_inserted_here_p (const struct bp_location *bl, const address_space *aspace, CORE_ADDR pc) { if (bl->inserted - && breakpoint_address_match (bl->pspace->aspace, bl->address, + && breakpoint_address_match (bl->pspace->aspace.get (), bl->address, aspace, pc)) { /* An unmapped overlay can't be a match. */ @@ -4508,7 +4508,7 @@ hardware_watchpoint_inserted_in_range (const address_space *aspace, continue; for (bp_location &loc : bpt.locations ()) - if (loc.pspace->aspace == aspace && loc.inserted) + if (loc.pspace->aspace.get () == aspace && loc.inserted) { CORE_ADDR l, h; @@ -7327,10 +7327,10 @@ breakpoint_location_address_match (struct bp_location *bl, const address_space *aspace, CORE_ADDR addr) { - return (breakpoint_address_match (bl->pspace->aspace, bl->address, + return (breakpoint_address_match (bl->pspace->aspace.get (), bl->address, aspace, addr) || (bl->length - && breakpoint_address_match_range (bl->pspace->aspace, + && breakpoint_address_match_range (bl->pspace->aspace.get (), bl->address, bl->length, aspace, addr))); } @@ -7347,7 +7347,7 @@ breakpoint_location_address_range_overlap (struct bp_location *bl, CORE_ADDR addr, int len) { if (gdbarch_has_global_breakpoints (current_inferior ()->arch ()) - || bl->pspace->aspace == aspace) + || bl->pspace->aspace.get () == aspace) { int bl_len = bl->length != 0 ? bl->length : 1; @@ -7404,8 +7404,10 @@ breakpoint_locations_match (const struct bp_location *loc1, /* We compare bp_location.length in order to cover ranged breakpoints. Keep this in sync with bp_location_is_less_than. */ - return (breakpoint_address_match (loc1->pspace->aspace, loc1->address, - loc2->pspace->aspace, loc2->address) + return (breakpoint_address_match (loc1->pspace->aspace.get (), + loc1->address, + loc2->pspace->aspace.get (), + loc2->address) && (loc1->loc_type == loc2->loc_type || sw_hw_bps_match) && loc1->length == loc2->length); } @@ -9565,8 +9567,9 @@ ranged_breakpoint::breakpoint_hit (const struct bp_location *bl, || ws.sig () != GDB_SIGNAL_TRAP) return 0; - return breakpoint_address_match_range (bl->pspace->aspace, bl->address, - bl->length, aspace, bp_addr); + return breakpoint_address_match_range (bl->pspace->aspace.get (), + bl->address, bl->length, aspace, + bp_addr); } /* Implement the "resources_needed" method for ranged breakpoints. */ @@ -12012,7 +12015,7 @@ code_breakpoint::breakpoint_hit (const struct bp_location *bl, || ws.sig () != GDB_SIGNAL_TRAP) return 0; - if (!breakpoint_address_match (bl->pspace->aspace, bl->address, + if (!breakpoint_address_match (bl->pspace->aspace.get (), bl->address, aspace, bp_addr)) return 0; |