On 08/08, Frederic Weisbecker wrote:
>
> I'm all for fixing this. May be we can start by backporting a patch that
> ignores the value of gen_len for instruction breakpoints in x86?
Or perhaps we can start with the something like below.
But probably we should move "attr.bp_len == HW_BREAKPOINT_LEN_1" check
from arch_build_bp_info() to its caller, arch_validate_hwbkpt_settings().
Because:
> But this bp_len
> should rather be used for range breakpoints on archs that support it.
Yes, exactly, and we already have the patches for amd, so bp->len can
be actually != 1 but currently we can't support because it is checked
in arch_build_bp_info().
Oleg.
--- x/arch/x86/kernel/hw_breakpoint.c
+++ x/arch/x86/kernel/hw_breakpoint.c
@@ -208,19 +208,16 @@ int arch_bp_generic_fields(int x86_len,
{
/* Type */
switch (x86_type) {
- case X86_BREAKPOINT_EXECUTE:
- if (x86_len != X86_BREAKPOINT_LEN_X)
- return -EINVAL;
-
- *gen_type = HW_BREAKPOINT_X;
- *gen_len = sizeof(long);
- return 0;
case X86_BREAKPOINT_WRITE:
*gen_type = HW_BREAKPOINT_W;
break;
case X86_BREAKPOINT_RW:
*gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
break;
+ case X86_BREAKPOINT_EXECUTE:
+ *gen_type = HW_BREAKPOINT_X;
+ if (x86_len == X86_BREAKPOINT_LEN_1)
+ break;
default:
return -EINVAL;
}
@@ -265,15 +262,11 @@ static int arch_build_bp_info(struct per
break;
case HW_BREAKPOINT_X:
info->type = X86_BREAKPOINT_EXECUTE;
- /*
- * x86 inst breakpoints need to have a specific undefined len.
- * But we still need to check userspace is not trying to setup
- * an unsupported length, to get a range breakpoint for example.
- */
- if (bp->attr.bp_len == sizeof(long)) {
- info->len = X86_BREAKPOINT_LEN_X;
- return 0;
- }
+ /* until we change tools/perf */
+ if (bp->attr.bp_len == sizeof(long))
+ bp->attr.bp_len = HW_BREAKPOINT_LEN_1;
+ if (bp->attr.bp_len == HW_BREAKPOINT_LEN_1)
+ break;
default:
return -EINVAL;
}
--
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