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LoongArch: Fix watchpoint setting error

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In the current code, when debugging the following code using gdb,
"invalid argument ..." message will be displayed.

lihui@bogon:~$ cat test.c
  #include <stdio.h>
  int a = 0;
  int main()
  {
	a = 1;
	return 0;
  }
lihui@bogon:~$ gcc -g test.c -o test
lihui@bogon:~$ gdb test
...
(gdb) watch a
Hardware watchpoint 1: a
(gdb) r
...
Invalid argument setting hardware debug registers

There are mainly two types of issues.

1. Some incorrect judgment condition existed in user_watch_state
   argument parsing, causing -EINVAL to be returned.

When setting up a watchpoint, gdb uses the ptrace interface,
ptrace(PTRACE_SETREGSET, tid, NT_LOONGARCH_HW_WATCH, (void *) &iov)).
Register values in user_watch_state as follows:

  addr[0] = 0x0, mask[0] = 0x0, ctrl[0] = 0x0
  addr[1] = 0x0, mask[1] = 0x0, ctrl[1] = 0x0
  addr[2] = 0x0, mask[2] = 0x0, ctrl[2] = 0x0
  addr[3] = 0x0, mask[3] = 0x0, ctrl[3] = 0x0
  addr[4] = 0x0, mask[4] = 0x0, ctrl[4] = 0x0
  addr[5] = 0x0, mask[5] = 0x0, ctrl[5] = 0x0
  addr[6] = 0x0, mask[6] = 0x0, ctrl[6] = 0x0
  addr[7] = 0x12000803c, mask[7] = 0x0, ctrl[7] = 0x610

In arch_bp_generic_fields(), return -EINVAL when ctrl.len is
LOONGARCH_BREAKPOINT_LEN_8(0b00). So delete the incorrect judgment here.

In ptrace_hbp_fill_attr_ctrl(), when note_type is NT_LOONGARCH_HW_WATCH
and ctrl[0] == 0x0, if ((type & HW_BREAKPOINT_RW) != type) will return
-EINVAL. Here ctrl.type should be set based on note_type, and unnecessary
judgments can be removed.

2. The watchpoint argument was not set correctly due to unnecessary
   offset and alignment_mask.

Modify ptrace_hbp_fill_attr_ctrl() and hw_breakpoint_arch_parse(), which
ensure the watchpont argument is set correctly.

All changes according to the LoongArch Reference Manual:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints

Cc: stable@vger.kernel.org
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Hui Li 2024-06-21 10:18:40 +08:00 committed by Huacai Chen
parent 120dd4118e
commit f63a47b34b
3 changed files with 21 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/loongarch/include/asm/hw_breakpoint.h
View File

@ -101,7 +101,7 @@ struct perf_event;
struct perf_event_attr;
extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
int *gen_len, int *gen_type, int *offset);
int *gen_len, int *gen_type);
extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
extern int hw_breakpoint_arch_parse(struct perf_event *bp,
const struct perf_event_attr *attr,

19
arch/loongarch/kernel/hw_breakpoint.c
View File

@ -283,7 +283,7 @@ int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
* to generic breakpoint descriptions.
*/
int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
int *gen_len, int *gen_type, int *offset)
int *gen_len, int *gen_type)
{
/* Type */
switch (ctrl.type) {
@ -303,11 +303,6 @@ int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
return -EINVAL;
}
if (!ctrl.len)
return -EINVAL;
*offset = __ffs(ctrl.len);
/* Len */
switch (ctrl.len) {
case LOONGARCH_BREAKPOINT_LEN_1:
@ -386,21 +381,17 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
struct arch_hw_breakpoint *hw)
{
int ret;
u64 alignment_mask, offset;
u64 alignment_mask;
/* Build the arch_hw_breakpoint. */
ret = arch_build_bp_info(bp, attr, hw);
if (ret)
return ret;
if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
alignment_mask = 0x7;
else
if (hw->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
alignment_mask = 0x3;
offset = hw->address & alignment_mask;
hw->address &= ~alignment_mask;
hw->ctrl.len <<= offset;
hw->address &= ~alignment_mask;
}
return 0;
}

32
arch/loongarch/kernel/ptrace.c
View File

@ -494,28 +494,14 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
struct arch_hw_breakpoint_ctrl ctrl,
struct perf_event_attr *attr)
{
int err, len, type, offset;
int err, len, type;
err = arch_bp_generic_fields(ctrl, &len, &type, &offset);
err = arch_bp_generic_fields(ctrl, &len, &type);
if (err)
return err;
switch (note_type) {
case NT_LOONGARCH_HW_BREAK:
if ((type & HW_BREAKPOINT_X) != type)
return -EINVAL;
break;
case NT_LOONGARCH_HW_WATCH:
if ((type & HW_BREAKPOINT_RW) != type)
return -EINVAL;
break;
default:
return -EINVAL;
}
attr->bp_len = len;
attr->bp_type = type;
attr->bp_addr += offset;
return 0;
}
@ -609,7 +595,19 @@ static int ptrace_hbp_set_ctrl(unsigned int note_type,
return PTR_ERR(bp);
attr = bp->attr;
decode_ctrl_reg(uctrl, &ctrl);
switch (note_type) {
case NT_LOONGARCH_HW_BREAK:
ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
break;
case NT_LOONGARCH_HW_WATCH:
decode_ctrl_reg(uctrl, &ctrl);
break;
default:
return -EINVAL;
}
err = ptrace_hbp_fill_attr_ctrl(note_type, ctrl, &attr);
if (err)
return err;