From f52e126cc7476196f44f3c313b7d9f0699a881fc Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 28 Jun 2016 09:42:25 +0530 Subject: ARC: unwind: ensure that .debug_frame is generated (vs. .eh_frame) With recent binutils update to support dwarf CFI pseudo-ops in gas, we now get .eh_frame vs. .debug_frame. Although the call frame info is exactly the same in both, the CIE differs, which the current kernel unwinder can't cope with. This broke both the kernel unwinder as well as loadable modules (latter because of a new unhandled relo R_ARC_32_PCREL from .rela.eh_frame in the module loader) The ideal solution would be to switch unwinder to .eh_frame. For now however we can make do by just ensureing .debug_frame is generated by removing -fasynchronous-unwind-tables .eh_frame generated with -gdwarf-2 -fasynchronous-unwind-tables .debug_frame generated with -gdwarf-2 Fixes STAR 9001058196 Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta --- arch/arc/Makefile | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch') diff --git a/arch/arc/Makefile b/arch/arc/Makefile index d4df6be66d58..85814e74677d 100644 --- a/arch/arc/Makefile +++ b/arch/arc/Makefile @@ -66,8 +66,6 @@ endif endif -cflags-$(CONFIG_ARC_DW2_UNWIND) += -fasynchronous-unwind-tables - # By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok ifeq ($(atleast_gcc48),y) cflags-$(CONFIG_ARC_DW2_UNWIND) += -gdwarf-2 -- cgit v1.2.3-59-g8ed1b From 9bd54517ee86cb164c734f72ea95aeba4804f10b Mon Sep 17 00:00:00 2001 From: Alexey Brodkin Date: Thu, 23 Jun 2016 11:00:39 +0300 Subject: arc: unwind: warn only once if DW2_UNWIND is disabled If CONFIG_ARC_DW2_UNWIND is disabled every time arc_unwind_core() gets called following message gets printed in debug console: ----------------->8--------------- CONFIG_ARC_DW2_UNWIND needs to be enabled ----------------->8--------------- That message makes sense if user indeed wants to see a backtrace or get nice function call-graphs in perf but what if user disabled unwinder for the purpose? Why pollute his debug console? So instead we'll warn user about possibly missing feature once and let him decide if that was what he or she really wanted. Signed-off-by: Alexey Brodkin Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta --- arch/arc/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c index e0efff15a5ae..b9192a653b7e 100644 --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -142,7 +142,7 @@ arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs, * prelogue is setup (callee regs saved and then fp set and not other * way around */ - pr_warn("CONFIG_ARC_DW2_UNWIND needs to be enabled\n"); + pr_warn_once("CONFIG_ARC_DW2_UNWIND needs to be enabled\n"); return 0; #endif -- cgit v1.2.3-59-g8ed1b