From: Greg Kroah-Hartman Date: Sun, 30 Apr 2017 21:47:25 +0000 (+0200) Subject: 3.18-stable patches X-Git-Tag: v4.4.66~6 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ca28562e2e69bd17290f416f3a54ebbc2f150ee6;p=thirdparty%2Fkernel%2Fstable-queue.git 3.18-stable patches added patches: ftrace-x86-fix-triple-fault-with-graph-tracing-and-suspend-to-ram.patch --- diff --git a/queue-3.18/ftrace-x86-fix-triple-fault-with-graph-tracing-and-suspend-to-ram.patch b/queue-3.18/ftrace-x86-fix-triple-fault-with-graph-tracing-and-suspend-to-ram.patch new file mode 100644 index 00000000000..d89002eed31 --- /dev/null +++ b/queue-3.18/ftrace-x86-fix-triple-fault-with-graph-tracing-and-suspend-to-ram.patch @@ -0,0 +1,82 @@ +From 34a477e5297cbaa6ecc6e17c042a866e1cbe80d6 Mon Sep 17 00:00:00 2001 +From: Josh Poimboeuf +Date: Thu, 13 Apr 2017 17:53:55 -0500 +Subject: ftrace/x86: Fix triple fault with graph tracing and suspend-to-ram + +From: Josh Poimboeuf + +commit 34a477e5297cbaa6ecc6e17c042a866e1cbe80d6 upstream. + +On x86-32, with CONFIG_FIRMWARE and multiple CPUs, if you enable function +graph tracing and then suspend to RAM, it will triple fault and reboot when +it resumes. + +The first fault happens when booting a secondary CPU: + +startup_32_smp() + load_ucode_ap() + prepare_ftrace_return() + ftrace_graph_is_dead() + (accesses 'kill_ftrace_graph') + +The early head_32.S code calls into load_ucode_ap(), which has an an +ftrace hook, so it calls prepare_ftrace_return(), which calls +ftrace_graph_is_dead(), which tries to access the global +'kill_ftrace_graph' variable with a virtual address, causing a fault +because the CPU is still in real mode. + +The fix is to add a check in prepare_ftrace_return() to make sure it's +running in protected mode before continuing. The check makes sure the +stack pointer is a virtual kernel address. It's a bit of a hack, but +it's not very intrusive and it works well enough. + +For reference, here are a few other (more difficult) ways this could +have potentially been fixed: + +- Move startup_32_smp()'s call to load_ucode_ap() down to *after* paging + is enabled. (No idea what that would break.) + +- Track down load_ucode_ap()'s entire callee tree and mark all the + functions 'notrace'. (Probably not realistic.) + +- Pause graph tracing in ftrace_suspend_notifier_call() or bringup_cpu() + or __cpu_up(), and ensure that the pause facility can be queried from + real mode. + +Reported-by: Paul Menzel +Signed-off-by: Josh Poimboeuf +Tested-by: Paul Menzel +Reviewed-by: Steven Rostedt (VMware) +Cc: "Rafael J . Wysocki" +Cc: linux-acpi@vger.kernel.org +Cc: Borislav Petkov +Cc: Len Brown +Link: http://lkml.kernel.org/r/5c1272269a580660703ed2eccf44308e790c7a98.1492123841.git.jpoimboe@redhat.com +Signed-off-by: Thomas Gleixner +Signed-off-by: Greg Kroah-Hartman + +--- + arch/x86/kernel/ftrace.c | 12 ++++++++++++ + 1 file changed, 12 insertions(+) + +--- a/arch/x86/kernel/ftrace.c ++++ b/arch/x86/kernel/ftrace.c +@@ -703,6 +703,18 @@ void prepare_ftrace_return(unsigned long + unsigned long return_hooker = (unsigned long) + &return_to_handler; + ++ /* ++ * When resuming from suspend-to-ram, this function can be indirectly ++ * called from early CPU startup code while the CPU is in real mode, ++ * which would fail miserably. Make sure the stack pointer is a ++ * virtual address. ++ * ++ * This check isn't as accurate as virt_addr_valid(), but it should be ++ * good enough for this purpose, and it's fast. ++ */ ++ if (unlikely((long)__builtin_frame_address(0) >= 0)) ++ return; ++ + if (unlikely(ftrace_graph_is_dead())) + return; + diff --git a/queue-3.18/series b/queue-3.18/series index 4758a54b8d1..5bf64a9ae28 100644 --- a/queue-3.18/series +++ b/queue-3.18/series @@ -22,3 +22,4 @@ mips-kgdb-use-kernel-context-for-sleeping-threads.patch p9_client_readdir-fix.patch input-i8042-add-clevo-p650rs-to-the-i8042-reset-list.patch nfsd-check-for-oversized-nfsv2-v3-arguments.patch +ftrace-x86-fix-triple-fault-with-graph-tracing-and-suspend-to-ram.patch