On Wed, Aug 01, 2018 at 03:00:22PM +0300, Dmitry Osipenko wrote: > Hello Abbott, > > I gave a quick whirl to your KASAN patches on top of current linux-next on > NVIDIA Tegra20 and here are couple notes: > > 1) Kernel is booting fine. > > 2) Loading test_kasan.ko makes KASAN to trap faulty memory accesses. > > 3) Running Tegra GPU 2D/3D tests works without any issue. > > 4) I wanted to try Tegra's video decoder driver under KASAN, but unfortunately > Xorg server and video player processes are getting stuck consuming 100% CPU and > processes are not KILL'able. > > I've tried to disable Opentegra Xorg driver and result is the same, you should > be able to reproduce the issue by just running some desktop environment. > > 5) There is a splat during kernels boot-up if CONFIG_FTRACE=y and > CONFIG_THUMB2_KERNEL=y. > > ftrace: allocating 40389 entries in 79 pages > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 0 at arch/arm/kernel/insn.c:15 __arm_gen_branch+0x7f/0x84 That basically means the branch is out of range for the instruction. It seems to suggest this is a Thumb2 kernel, and relative offset of the function to the mcount function is beyond the Thumb2 branch-link instruction range. (See ftrace_code_disable() in kernel/trace/ftrace.c). This unfortunately provokes two warnings - one from the instruction generation code, and one from the ftrace code: > WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2059 ftrace_bug+0x1d7/0x28c > Initializing ftrace call sites > ftrace record flags: 0 > (0) > expected tramp: c010f7dd This may not be the affected function - it looks like the ftrace code bails out on the first ftrace_code_disable() that fails... Which ever function it is, the compiler would have had to create code that would allow it to get to the mcount function, so it suggests that the ftrace code doesn't know about some compiler trick... -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 13.8Mbps down 630kbps up According to speedtest.net: 13Mbps down 490kbps up -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
