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This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
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This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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Enable displaced stepping over a BR/BLR instruction
Displaced stepping over an instruction executes a instruction in a
scratch area and then manually fixes up the PC address to leave
execution where it would have been if the instruction were in its
original location.
The BR instruction does not need modification in order to run correctly
at a different address, but the displaced step fixup method should not
manually adjust the PC since the BR instruction sets that value already.
The BLR instruction should also avoid such a fixup, but must also have
the link register modified to point to just after the original code
location rather than back to the scratch location.
This patch adds the above functionality.
We add this functionality by modifying aarch64_displaced_step_others
rather than by adding a new visitor method to aarch64_insn_visitor.
We choose this since it seems that visitor approach is designed
specifically for PC relative instructions (which must always be modified
when executed in a different location).
It seems that the BR and BLR instructions are more like the RET
instruction which is already handled specially in
aarch64_displaced_step_others.
This also means the gdbserver code to relocate an instruction when
creating a fast tracepoint does not need to be modified, since nothing
special is needed for the BR and BLR instructions there.
Regression tests showed nothing untoward on native aarch64 (though it
took a while for me to get the testcase to account for PIE).
------#####
Original observed (mis)behaviour before was that displaced stepping over
a BR or BLR instruction would not execute the function they called.
Most easily seen by putting a breakpoint with a condition on such an
instruction and a print statement in the functions they called.
When run with the breakpoint enabled the function is not called and
"numargs called" is not printed.
When run with the breakpoint disabled the function is called and the
message is printed.
--- GDB Session
~ [15:57:14] % gdb ../using-blr
Reading symbols from ../using-blr...done.
(gdb) disassemble blr_call_value
Dump of assembler code for function blr_call_value:
...
0x0000000000400560 <+28>: blr x2
...
0x00000000004005b8 <+116>: ret
End of assembler dump.
(gdb) break *0x0000000000400560
Breakpoint 1 at 0x400560: file ../using-blr.c, line 22.
(gdb) condition 1 10 == 0
(gdb) run
Starting program: /home/matmal01/using-blr
[Inferior 1 (process 33279) exited with code 012]
(gdb) disable 1
(gdb) run
Starting program: /home/matmal01/using-blr
numargs called
[Inferior 1 (process 33289) exited with code 012]
(gdb)
Test program:
---- using-blr ----
\#include <stdio.h>
typedef int (foo) (int, int);
typedef void (bar) (int, int);
struct sls_testclass {
foo *x;
bar *y;
int left;
int right;
};
__attribute__ ((noinline))
int blr_call_value (struct sls_testclass x)
{
int retval = x.x(x.left, x.right);
if (retval % 10)
return 100;
return 9;
}
__attribute__ ((noinline))
int blr_call (struct sls_testclass x)
{
x.y(x.left, x.right);
if (x.left % 10)
return 100;
return 9;
}
int
numargs (__attribute__ ((unused)) int left, __attribute__ ((unused)) int right)
{
printf("numargs called\n");
return 10;
}
void
altfunc (__attribute__ ((unused)) int left, __attribute__ ((unused)) int right)
{
printf("altfunc called\n");
}
int main(int argc, char **argv)
{
struct sls_testclass x = { .x = numargs, .y = altfunc, .left = 1, .right = 2 };
if (argc > 2)
{
blr_call (x);
}
else
blr_call_value (x);
return 10;
}
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This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
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gdb/ChangeLog:
Update copyright year range in all GDB files.
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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.
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gdb/ChangeLog:
Update copyright year range in all GDB files
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LR is a caller-save register, so, if inline asm does BL (which touches
LR), we should mark LR clobbered.
gdb/testsuite:
2017-10-27 Yao Qi <yao.qi@linaro.org>
* gdb.arch/insn-reloc.c (can_relocate_bl): Mark "x30" clobbered.
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This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update year range in copyright notice of all files.
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This patch adds more tests in gdb.arch/insn-reloc.c to cover
instruction BL and cover B.CON when CON is false. These new added
tests can be used for displaced stepping too.
gdb/testsuite:
2015-10-12 Yao Qi <yao.qi@linaro.org>
* gdb.arch/insn-reloc.c (can_relocate_bcond): Rename to ...
(can_relocate_bcond_true): ... it.
(can_relocate_bcond_false): New function.
(foo): Likewise.
(can_relocate_bl): Likewise.
(testcases) [__aarch64__]: Add can_relocate_bcond_false and
can_relocate_bl.
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This test case makes sure that relocating PC relative instructions does
not change their behaviors. All PC relative AArch64 instructions are
covered. While call and jump (32 bit relative) instructions are covered
on x86.
The test case creates a static array of function pointers for each
supported architecture. Each function in this array tests a specific
instruction using inline assembly. They all need to contain a symbol in
the form of 'set_point\[0-9\]+' and finish by either calling pass or
fail. The number of 'set_pointN' needs to go from 0 to
(ARRAY_SIZE - 1).
The test will:
- look up the number of function pointers in the static array.
- set fast tracepoints on each 'set_point\[0-9\]+' symbol, one in each
functions from 0 to (ARRAY_SIZE - 1).
- run the trace experiment and make sure the pass function is called for
every function.
gdb/testsuite/ChangeLog:
* gdb.arch/insn-reloc.c: New file.
* gdb.arch/ftrace-insn-reloc.exp: New file.
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