LoongArch: Fix watchpoint setting error

commit f63a47b34b140ed1ca39d7e4bd4f1cdc617fc316 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/loongarch/include/asm/hw_breakpoint.h b/arch/loongarch/include/asm/hw_breakpoint.h
index 21447fb1efc778a12c828dd9034fd8ba51db0263..a8ce580f4fc6ff12d0a29f71fe6a0697e761bae9 100644 (file)
--- a/arch/loongarch/include/asm/hw_breakpoint.h
+++ b/arch/loongarch/include/asm/hw_breakpoint.h
@@ -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,

diff --git a/arch/loongarch/kernel/hw_breakpoint.c b/arch/loongarch/kernel/hw_breakpoint.c
index fc55c4de2a11ff5ac765bfc0abb9a0a719b7cb66..950b2b8a82ee07bed4bc21909be0c9aa65935380 100644 (file)
--- a/arch/loongarch/kernel/hw_breakpoint.c
+++ b/arch/loongarch/kernel/hw_breakpoint.c
@@ -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;
 }

diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
index c114c5ef13325af024be5772b396690bbab7cbc4..16b756c6049bc85b8e8b322581c5bd7177659e3b 100644 (file)
--- a/arch/loongarch/kernel/ptrace.c
+++ b/arch/loongarch/kernel/ptrace.c
@@ -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;