Messages in this thread | | | Date | Fri, 28 Feb 2014 16:47:08 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86 trace: Fix page fault tracing bug |
| |
On Fri, Feb 28, 2014 at 04:33:40PM +0100, Jiri Olsa wrote:
While I like the idea of just pushing up the CR2 read; the below does the read too late still, exception_enter() also has a tracepoint in.
> @@ -1267,9 +1269,18 @@ dotraplinkage void __kprobes > trace_do_page_fault(struct pt_regs *regs, unsigned long error_code) > { > enum ctx_state prev_state; > + unsigned long address; > > prev_state = exception_enter(); > + > + /* > + * The tracepoint processing could trigger another page > + * fault (user space callchain reading) and destroy the > + * original cr2 value, so read the faulting address now. > + */ > + address = read_cr2(); > + > trace_page_fault_entries(regs, error_code); > - __do_page_fault(regs, error_code); > + __do_page_fault(regs, error_code, address); > exception_exit(prev_state); > } > -- > 1.7.11.7 >
| |