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Catch exceptions thrown from gdbarch_skip_prologue
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PR 21555 is caused by the exception during the prologue analysis when re-set
a breakpoint.

(gdb) bt
 #0  memory_error_message (err=TARGET_XFER_E_IO, gdbarch=0x153db50, memaddr=93824992233232) at ../../binutils-gdb/gdb/corefile.c:192
 #1  0x00000000005718ed in memory_error (err=TARGET_XFER_E_IO, memaddr=memaddr@entry=93824992233232) at ../../binutils-gdb/gdb/corefile.c:220
 #2  0x00000000005719d6 in read_memory_object (object=object@entry=TARGET_OBJECT_CODE_MEMORY, memaddr=93824992233232, memaddr@entry=1, myaddr=myaddr@entry=0x7fffffffd0a0 "P\333S\001", len=len@entry=1) at ../../binutils-gdb/gdb/corefile.c:259
 #3  0x0000000000571c6e in read_code (len=1, myaddr=0x7fffffffd0a0 "P\333S\001", memaddr=<optimized out>) at ../../binutils-gdb/gdb/corefile.c:287
 #4  read_code_unsigned_integer (memaddr=memaddr@entry=93824992233232, len=len@entry=1, byte_order=byte_order@entry=BFD_ENDIAN_LITTLE)                          at ../../binutils-gdb/gdb/corefile.c:362
 #5  0x000000000041d4a0 in amd64_analyze_prologue (gdbarch=gdbarch@entry=0x153db50, pc=pc@entry=93824992233232, current_pc=current_pc@entry=18446744073709551615, cache=cache@entry=0x7fffffffd1e0) at ../../binutils-gdb/gdb/amd64-tdep.c:2310
 #6  0x000000000041e404 in amd64_skip_prologue (gdbarch=0x153db50, start_pc=93824992233232) at ../../binutils-gdb/gdb/amd64-tdep.c:2459
 #7  0x000000000067bfb0 in skip_prologue_sal (sal=sal@entry=0x7fffffffd4e0) at ../../binutils-gdb/gdb/symtab.c:3628
 #8  0x000000000067c4d8 in find_function_start_sal (sym=sym@entry=0x1549960, funfirstline=1) at ../../binutils-gdb/gdb/symtab.c:3501
 #9  0x000000000060999d in symbol_to_sal (result=result@entry=0x7fffffffd5f0, funfirstline=<optimized out>, sym=sym@entry=0x1549960) at ../../binutils-gdb/gdb/linespec.c:3860
....
 #16 0x000000000054b733 in location_to_sals (b=b@entry=0x15792d0, location=0x157c230, search_pspace=search_pspace@entry=0x1148120, found=found@entry=0x7fffffffdc64) at ../../binutils-gdb/gdb/breakpoint.c:14211
 #17 0x000000000054c1f5 in breakpoint_re_set_default (b=0x15792d0) at ../../binutils-gdb/gdb/breakpoint.c:14301
 #18 0x00000000005412a9 in breakpoint_re_set_one (bint=bint@entry=0x15792d0) at ../../binutils-gdb/gdb/breakpoint.c:14412

This problem can be fixed by

 - either each prologue analyzer doesn't throw exception,
 - or catch the exception thrown from gdbarch_skip_prologue,

I choose the latter because the former needs to fix *every* prologue
analyzer to not throw exception.

This error can be reproduced by changing reread.exp.  The test reread.exp
has already test that breakpoint can be reset correctly after the
executable is re-read.  This patch extends this test by compiling test c
file with and without -fPIE.

(gdb) run ^M
The program being debugged has been started already.^M
Start it from the beginning? (y or n) y^M
x86_64/gdb/testsuite/outputs/gdb.base/reread/reread' has changed; re-reading symbols.
Error in re-setting breakpoint 1: Cannot access memory at address 0x555555554790^M
Error in re-setting breakpoint 2: Cannot access memory at address 0x555555554790^M
Starting program: /scratch/yao/gdb/build-git/x86_64/gdb/testsuite/outputs/gdb.base/reread/reread ^M
This is foo^M
[Inferior 1 (process 27720) exited normally]^M
(gdb) FAIL: gdb.base/reread.exp: opts= "-fPIE" "ldflags=-pie" : run to foo() second time (the program exited)

This patch doesn't re-indent the code, to keep the patch simple.

gdb:

2017-07-25  Yao Qi  <[email protected]>

	PR gdb/21555
	* arch-utils.c (gdbarch_skip_prologue_noexcept): New function.
	* arch-utils.h (gdbarch_skip_prologue_noexcept): Declare.
	* infrun.c: Include arch-utils.h
	(handle_step_into_function): Call gdbarch_skip_prologue_noexcept.
	(handle_step_into_function_backward): Likewise.
	* symtab.c (skip_prologue_sal): Likewise.

gdb/testsuite:

2017-07-25  Yao Qi  <[email protected]>

	PR gdb/21555
	* gdb.base/reread.exp: Wrap the whole test with two kinds of
	compilation flags, with -fPIE and without -fPIE.
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Yao Qi committed Jul 25, 2017
1 parent 02ad7fc commit 46a6226
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Showing 5 changed files with 154 additions and 108 deletions.
18 changes: 18 additions & 0 deletions gdb/arch-utils.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -985,6 +985,24 @@ default_print_insn (bfd_vma memaddr, disassemble_info *info)
return (*disassemble_fn) (memaddr, info);
}

/* See arch-utils.h. */

CORE_ADDR
gdbarch_skip_prologue_noexcept (gdbarch *gdbarch, CORE_ADDR pc) noexcept
{
CORE_ADDR new_pc = pc;

TRY
{
new_pc = gdbarch_skip_prologue (gdbarch, pc);
}
CATCH (ex, RETURN_MASK_ALL)
{}
END_CATCH

return new_pc;
}

/* -Wmissing-prototypes */
extern initialize_file_ftype _initialize_gdbarch_utils;

Expand Down
6 changes: 6 additions & 0 deletions gdb/arch-utils.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -268,4 +268,10 @@ extern void default_guess_tracepoint_registers (struct gdbarch *gdbarch,

extern int default_print_insn (bfd_vma memaddr, disassemble_info *info);

/* Wrapper to gdbarch_skip_prologue, but doesn't throw exception. Catch
exception thrown from gdbarch_skip_prologue, and return PC. */

extern CORE_ADDR gdbarch_skip_prologue_noexcept (gdbarch *gdbarch,
CORE_ADDR pc) noexcept;

#endif
9 changes: 5 additions & 4 deletions gdb/infrun.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,7 @@
#include "common/enum-flags.h"
#include "progspace-and-thread.h"
#include "common/gdb_optional.h"
#include "arch-utils.h"

/* Prototypes for local functions */

Expand Down Expand Up @@ -7317,8 +7318,8 @@ handle_step_into_function (struct gdbarch *gdbarch,

cust = find_pc_compunit_symtab (stop_pc);
if (cust != NULL && compunit_language (cust) != language_asm)
ecs->stop_func_start = gdbarch_skip_prologue (gdbarch,
ecs->stop_func_start);
ecs->stop_func_start
= gdbarch_skip_prologue_noexcept (gdbarch, ecs->stop_func_start);

stop_func_sal = find_pc_line (ecs->stop_func_start, 0);
/* Use the step_resume_break to step until the end of the prologue,
Expand Down Expand Up @@ -7396,8 +7397,8 @@ handle_step_into_function_backward (struct gdbarch *gdbarch,

cust = find_pc_compunit_symtab (stop_pc);
if (cust != NULL && compunit_language (cust) != language_asm)
ecs->stop_func_start = gdbarch_skip_prologue (gdbarch,
ecs->stop_func_start);
ecs->stop_func_start
= gdbarch_skip_prologue_noexcept (gdbarch, ecs->stop_func_start);

stop_func_sal = find_pc_line (stop_pc, 0);

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3 changes: 2 additions & 1 deletion gdb/symtab.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@
#include "progspace-and-thread.h"
#include "common/gdb_optional.h"
#include "filename-seen-cache.h"
#include "arch-utils.h"

/* Forward declarations for local functions. */

Expand Down Expand Up @@ -3627,7 +3628,7 @@ skip_prologue_sal (struct symtab_and_line *sal)
if (gdbarch_skip_entrypoint_p (gdbarch))
pc = gdbarch_skip_entrypoint (gdbarch, pc);
if (skip)
pc = gdbarch_skip_prologue (gdbarch, pc);
pc = gdbarch_skip_prologue_noexcept (gdbarch, pc);

/* For overlays, map pc back into its mapped VMA range. */
pc = overlay_mapped_address (pc, section);
Expand Down
226 changes: 123 additions & 103 deletions gdb/testsuite/gdb.base/reread.exp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,111 +15,131 @@

set prototypes 1

# build the first test case
# Build programs in PIE mode, to reproduce PR 21555.
foreach_with_prefix opts {
{ "" "" }
{ "-fPIE" "ldflags=-pie" } } {

set testfile1 "reread1"
set srcfile1 ${testfile1}.c
# Cygwin needs $EXEEXT.
set binfile1 [standard_output_file ${testfile1}$EXEEXT]

if { [gdb_compile "${srcdir}/${subdir}/${srcfile1}" "${binfile1}" executable {debug nowarnings}] != "" } {
untested "failed to compile first testcase"
return -1
}

# build the second test case

set testfile2 "reread2"
set srcfile2 ${testfile2}.c
set binfile2 [standard_output_file ${testfile2}$EXEEXT]

if { [gdb_compile "${srcdir}/${subdir}/${srcfile2}" "${binfile2}" executable {debug nowarnings}] != ""
&& [gdb_compile "${srcdir}/${subdir}/${srcfile2}" "${binfile2}" executable {debug nowarnings additional_flags=-DNO_SECTIONS}] != ""} {
untested "failed to compile second testcase"
return -1
}

# Start with a fresh gdb.

set testfile "reread"
set binfile [standard_output_file ${testfile}$EXEEXT]

gdb_start
gdb_reinitialize_dir $srcdir/$subdir

# Load the first executable.

gdb_rename_execfile ${binfile1} ${binfile}
gdb_load ${binfile}

# Set a breakpoint at foo

gdb_test "break foo" \
"Breakpoint.*at.* file .*$srcfile1, line 14.*" \
"breakpoint foo in first file"


# Run, should see "Breakpoint 1, foo () at hello1.c:14"

gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*$srcfile1:14.*" "run to foo()"

# Restore first executable to its original name, and move
# second executable into its place. Ensure that the new
# executable is at least a second newer than the old.

gdb_rename_execfile ${binfile} ${binfile1}
gdb_rename_execfile ${binfile2} ${binfile}
gdb_test "shell sleep 1" ".*" ""
gdb_touch_execfile ${binfile}

# Run a second time; GDB should detect that the executable has changed
# and reset the breakpoints correctly.
# Should see "Breakpoint 1, foo () at reread2.c:9"

set test "run to foo() second time"
if [is_remote target] {
unsupported $test
} else {
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*:9.*" $test
}


### Second pass: verify that GDB checks the executable file's
### timestamp when the program is *restarted*, not just when it exits.

if [is_remote target] {
unsupported "second pass: GDB should check for changes before running"
} else {

# Put the older executable back in place.
gdb_rename_execfile ${binfile} ${binfile2}
gdb_rename_execfile ${binfile1} ${binfile}

# Restart GDB entirely.
clean_restart ${binfile}

# Set a breakpoint on foo and run to it.
gdb_test "break foo" \
"Breakpoint.*at.* file .*$srcfile1, line 14.*" \
"second pass: breakpoint foo in first file"
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*$srcfile1:14.*" "second pass: run to foo()"

# This time, let the program run to completion. If GDB checks the
# executable file's timestamp now, it won't notice any change.
gdb_continue_to_end "second pass"

# Now move the newer executable into place, and re-run. GDB
# should still notice that the executable file has changed,
# and still re-set the breakpoint appropriately.
gdb_rename_execfile ${binfile} ${binfile1}
gdb_rename_execfile ${binfile2} ${binfile}
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*:9.*" "second pass: run to foo() second time"
}
# build the first test case

set testfile1 "reread1"
set srcfile1 ${testfile1}.c
# Cygwin needs $EXEEXT.
set binfile1 [standard_output_file ${testfile1}$EXEEXT]

set testfile1_opt [list debug nowarnings \
additional_flags=[lindex $opts 0] \
[lindex $opts 1] ]
if { [gdb_compile "${srcdir}/${subdir}/${srcfile1}" "${binfile1}" \
executable ${testfile1_opt}] != "" } {
untested "failed to compile first testcase"
return -1
}

# build the second test case

set testfile2 "reread2"
set srcfile2 ${testfile2}.c
set binfile2 [standard_output_file ${testfile2}$EXEEXT]

set testfile2_opt1 [list debug nowarnings \
additional_flags=[lindex $opts 0] \
[lindex $opts 1]]
set testfile2_op2 [list debug nowarnings \
"additional_flags=-DNO_SECTIONS [lindex $opts 0]" \
[lindex $opts 1]]
if { [gdb_compile "${srcdir}/${subdir}/${srcfile2}" "${binfile2}" \
executable ${testfile2_opt1}] != ""
&& [gdb_compile "${srcdir}/${subdir}/${srcfile2}" "${binfile2}" \
executable ${testfile2_opt2}] != ""} {
untested "failed to compile second testcase"
return -1
}

# Start with a fresh gdb.

set testfile "reread"
set binfile [standard_output_file ${testfile}$EXEEXT]

gdb_start
gdb_reinitialize_dir $srcdir/$subdir

# Load the first executable.

gdb_rename_execfile ${binfile1} ${binfile}
gdb_load ${binfile}

# Set a breakpoint at foo

gdb_test "break foo" \
"Breakpoint.*at.* file .*$srcfile1, line 14.*" \
"breakpoint foo in first file"


# Run, should see "Breakpoint 1, foo () at hello1.c:14"

gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*$srcfile1:14.*" "run to foo()"

# Restore first executable to its original name, and move
# second executable into its place. Ensure that the new
# executable is at least a second newer than the old.

gdb_rename_execfile ${binfile} ${binfile1}
gdb_rename_execfile ${binfile2} ${binfile}
gdb_test "shell sleep 1" ".*" ""
gdb_touch_execfile ${binfile}

# Run a second time; GDB should detect that the executable has changed
# and reset the breakpoints correctly.
# Should see "Breakpoint 1, foo () at reread2.c:9"

set test "run to foo() second time"
if [is_remote target] {
unsupported $test
} else {
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*:9.*" $test
}


### Second pass: verify that GDB checks the executable file's
### timestamp when the program is *restarted*, not just when it exits.

if [is_remote target] {
unsupported "second pass: GDB should check for changes before running"
} else {

# Put the older executable back in place.
gdb_rename_execfile ${binfile} ${binfile2}
gdb_rename_execfile ${binfile1} ${binfile}

# Restart GDB entirely.
clean_restart ${binfile}

# Set a breakpoint on foo and run to it.
gdb_test "break foo" \
"Breakpoint.*at.* file .*$srcfile1, line 14.*" \
"second pass: breakpoint foo in first file"
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*$srcfile1:14.*" \
"second pass: run to foo()"

# This time, let the program run to completion. If GDB checks the
# executable file's timestamp now, it won't notice any change.
gdb_continue_to_end "second pass"

# Now move the newer executable into place, and re-run. GDB
# should still notice that the executable file has changed,
# and still re-set the breakpoint appropriately.
gdb_rename_execfile ${binfile} ${binfile1}
gdb_rename_execfile ${binfile2} ${binfile}
gdb_run_cmd
gdb_test "" "Breakpoint.* foo .* at .*:9.*" \
"second pass: run to foo() second time"
}

}
# End of tests.

return 0

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