From cd01544a268ad8ee5b1dfe42c4393f1095f86879 Mon Sep 17 00:00:00 2001 From: Alistair Strachan Date: Fri, 14 Dec 2018 14:36:37 -0800 Subject: [PATCH] x86/vdso: Pass --eh-frame-hdr to the linker Commit 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link") accidentally broke unwinding from userspace, because ld would strip the .eh_frame sections when linking. Originally, the compiler would implicitly add --eh-frame-hdr when invoking the linker, but when this Makefile was converted from invoking ld via the compiler, to invoking it directly (like vmlinux does), the flag was missed. (The EH_FRAME section is important for the VDSO shared libraries, but not for vmlinux.) Fix the problem by explicitly specifying --eh-frame-hdr, which restores parity with the old method. See relevant bug reports for additional info: https://bugzilla.kernel.org/show_bug.cgi?id=201741 https://bugzilla.redhat.com/show_bug.cgi?id=1659295 Fixes: 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link") Reported-by: Florian Weimer Reported-by: Carlos O'Donell Reported-by: "H. J. Lu" Signed-off-by: Alistair Strachan Signed-off-by: Borislav Petkov Tested-by: Laura Abbott Cc: Andy Lutomirski Cc: Carlos O'Donell Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joel Fernandes Cc: kernel-team@android.com Cc: Laura Abbott Cc: stable Cc: Thomas Gleixner Cc: X86 ML Link: https://lkml.kernel.org/r/20181214223637.35954-1-astrachan@google.com --- arch/x86/entry/vdso/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 0624bf2..5bfe224 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -171,7 +171,8 @@ quiet_cmd_vdso = VDSO $@ sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@' VDSO_LDFLAGS = -shared $(call ld-option, --hash-style=both) \ - $(call ld-option, --build-id) -Bsymbolic + $(call ld-option, --build-id) $(call ld-option, --eh-frame-hdr) \ + -Bsymbolic GCOV_PROFILE := n # -- 2.7.4