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.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201741 Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1659295 Reported-by: Florian Weimer fweimer@redhat.com Reported-by: Carlos O'Donell carlos@redhat.com Reported-by: "H. J. Lu" hjl.tools@gmail.com Tested-by: Laura Abbott labbott@redhat.com Fixes: 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link") Cc: stable@vger.kernel.org Cc: Andy Lutomirski luto@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: "H. Peter Anvin" hpa@zytor.com Cc: X86 ML x86@kernel.org Cc: Joel Fernandes joel@joelfernandes.org Cc: kernel-team@android.com Signed-off-by: Alistair Strachan astrachan@google.com --- v2: Updated commit message, no changes to the code 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 141d415a8c80..c3d7ccd25381 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
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Commit-ID: cd01544a268ad8ee5b1dfe42c4393f1095f86879 Gitweb: https://git.kernel.org/tip/cd01544a268ad8ee5b1dfe42c4393f1095f86879 Author: Alistair Strachan astrachan@google.com AuthorDate: Fri, 14 Dec 2018 14:36:37 -0800 Committer: Borislav Petkov bp@suse.de CommitDate: Sat, 15 Dec 2018 11:37:51 +0100
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 fweimer@redhat.com Reported-by: Carlos O'Donell carlos@redhat.com Reported-by: "H. J. Lu" hjl.tools@gmail.com Signed-off-by: Alistair Strachan astrachan@google.com Signed-off-by: Borislav Petkov bp@suse.de Tested-by: Laura Abbott labbott@redhat.com Cc: Andy Lutomirski luto@kernel.org Cc: Carlos O'Donell carlos@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Joel Fernandes joel@joelfernandes.org Cc: kernel-team@android.com Cc: Laura Abbott labbott@redhat.com Cc: stable stable@vger.kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: X86 ML x86@kernel.org 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 0624bf2266fd..5bfe2243a08f 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
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