Messages in this thread | | | Date | Fri, 9 Aug 2013 18:45:50 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 0/1] (Was: Linux 3.11-rc4) |
| |
On Thu, Aug 08, 2013 at 08:15:21PM +0200, Oleg Nesterov wrote: > 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.
(commented on the diff 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().
Hmm, but how moving that to arch_validate_hwbkpt_seetings() would solve the issue?
> > 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;
Too bad we need to keep that compatibility around. Do you think this could be a problem for AMD range breakpoints?
We can also fix the tools, then may be we'll be able to remove the kernel hack compatibility in a few years.
Oh I need to check other archs as well.
thanks.
> + if (bp->attr.bp_len == HW_BREAKPOINT_LEN_1) > + break; > default: > return -EINVAL; > } >
| |