On Fri, Jan 20, 2017 at 10:17:57AM +0100, Jiri Slaby wrote: > On 01/06/2017, 03:55 PM, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > From 847fa1a6d3d00f3bdf68ef5fa4a786f644a0dd67 Mon Sep 17 00:00:00 2001 > > From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx> > > Date: Thu, 8 Dec 2016 12:48:26 -0500 > > Subject: ftrace/x86_32: Set ftrace_stub to weak to prevent gcc from using short jumps to it > > > > From: Steven Rostedt (Red Hat) <rostedt@xxxxxxxxxxx> > > > > commit 847fa1a6d3d00f3bdf68ef5fa4a786f644a0dd67 upstream. > > > > With new binutils, gcc may get smart with its optimization and change a jmp > > from a 5 byte jump to a 2 byte one even though it was jumping to a global > > function. But that global function existed within a 2 byte radius, and gcc > > was able to optimize it. Unfortunately, that jump was also being modified > > when function graph tracing begins. Since ftrace expected that jump to be 5 > > bytes, but it was only two, it overwrote code after the jump, causing a > > crash. > > > > This was fixed for x86_64 with commit 8329e818f149, with the same subject as > > this commit, but nothing was done for x86_32. > > Greg, > > can we have the x86_64 fix (8329e818f149) in 4.4 too? Ah, yes, I totally missed that. I'll queue it up after this next round of kernels goes out in a few hours. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html