binutils-gdb/gdb/nat/loongarch-linux-hw-point.h
Hui Li 6ced1278fc gdb: LoongArch: Add support for hardware breakpoint
LoongArch defines hardware watchpoint functions for fetch operations.
After the software configures the watchpoints for fetch, the processor
hardware will monitor the access addresses of the fetch operations and
trigger a watchpoint exception when the watchpoint setting conditions
are met.

Hardware watchpoints for fetch operations is used to implement hardware
breakpoint function on LoongArch. Refer to the following document for
hardware breakpoint.
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints

A simple test is as follows:

lihui@bogon:~$ cat test.c
  #include <stdio.h>
  int a = 0;
  int main()
  {
        printf("start test\n");
        a = 1;
        printf("a = %d\n", a);
        printf("end test\n");
        return 0;
  }
lihui@bogon:~$ gcc -g test.c -o test

without this patch:

lihui@bogon:~$ gdb test
...
(gdb) start
...
Temporary breakpoint 1, main () at test.c:5
5               printf("start test\n");
(gdb) hbreak 8
No hardware breakpoint support in the target.

with this patch:

lihui@bogon:~$ gdb test
...
(gdb) start
...

Temporary breakpoint 1, main () at test.c:5
5               printf("start test\n");
(gdb) hbreak 8
Hardware assisted breakpoint 2 at 0x1200006ec: file test.c, line 8.
(gdb) c
Continuing.
start test
a = 1

Breakpoint 2, main () at test.c:8
8               printf("end test\n");
(gdb) c
Continuing.
end test
[Inferior 1 (process 25378) exited normally]

Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
2024-06-25 05:50:29 +08:00

127 lines
4.1 KiB
C

/* Native-dependent code for GNU/Linux on LoongArch processors.
Copyright (C) 2024 Free Software Foundation, Inc.
Contributed by Loongson Ltd.
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 NAT_LOONGARCH_LINUX_HW_POINT_H
#define NAT_LOONGARCH_LINUX_HW_POINT_H
#include "gdbsupport/break-common.h" /* For enum target_hw_bp_type. */
#include "nat/loongarch-hw-point.h"
struct loongarch_user_watch_state {
uint64_t dbg_info;
struct {
uint64_t addr;
uint64_t mask;
uint32_t ctrl;
uint32_t pad;
} dbg_regs[8];
};
/* Macros to extract fields from the hardware debug information word. */
#define LOONGARCH_DEBUG_NUM_SLOTS(x) ((x) & 0xffff)
/* Each bit of a variable of this type is used to indicate whether a
hardware breakpoint or watchpoint setting has been changed since
the last update.
Bit N corresponds to the Nth hardware breakpoint or watchpoint
setting which is managed in loongarch_debug_reg_state, where N is
valid between 0 and the total number of the hardware breakpoint or
watchpoint debug registers minus 1.
When bit N is 1, the corresponding breakpoint or watchpoint setting
has changed, and therefore the corresponding hardware debug
register needs to be updated via the ptrace interface.
In the per-thread arch-specific data area, we define two such
variables for per-thread hardware breakpoint and watchpoint
settings respectively.
This type is part of the mechanism which helps reduce the number of
ptrace calls to the kernel, i.e. avoid asking the kernel to write
to the debug registers with unchanged values. */
typedef ULONGEST dr_changed_t;
/* Set each of the lower M bits of X to 1; assert X is wide enough. */
#define DR_MARK_ALL_CHANGED(x, m) \
do \
{ \
gdb_assert (sizeof ((x)) * 8 >= (m)); \
(x) = (((dr_changed_t)1 << (m)) - 1); \
} while (0)
#define DR_MARK_N_CHANGED(x, n) \
do \
{ \
(x) |= ((dr_changed_t)1 << (n)); \
} while (0)
#define DR_CLEAR_CHANGED(x) \
do \
{ \
(x) = 0; \
} while (0)
#define DR_HAS_CHANGED(x) ((x) != 0)
#define DR_N_HAS_CHANGED(x, n) ((x) & ((dr_changed_t)1 << (n)))
/* Per-thread arch-specific data we want to keep. */
struct arch_lwp_info
{
/* When bit N is 1, it indicates the Nth hardware breakpoint or
watchpoint register pair needs to be updated when the thread is
resumed; see loongarch_linux_prepare_to_resume. */
dr_changed_t dr_changed_bp;
dr_changed_t dr_changed_wp;
};
/* Call ptrace to set the thread TID's hardware breakpoint/watchpoint
registers with data from *STATE. */
void loongarch_linux_set_debug_regs (struct loongarch_debug_reg_state *state,
int tid, int watchpoint);
/* Get the hardware debug register capacity information from the
process represented by TID. */
void loongarch_linux_get_debug_reg_capacity (int tid);
/* Return the debug register state for process PID. If no existing
state is found for this process, return nullptr. */
struct loongarch_debug_reg_state *loongarch_lookup_debug_reg_state (pid_t pid);
/* Return the debug register state for process PID. If no existing
state is found for this process, create new state. */
struct loongarch_debug_reg_state *loongarch_get_debug_reg_state (pid_t pid);
/* Remove any existing per-process debug state for process PID. */
void loongarch_remove_debug_reg_state (pid_t pid);
#endif /* NAT_LOONGARCH_LINUX_HW_POINT_H */