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[73.19.79.57]) by smtp.gmail.com with ESMTPSA id x12sm6425217pgr.55.2018.12.14.14.32.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Dec 2018 14:32:07 -0800 (PST) Subject: Re: [PATCH] x86: vdso: Pass --eh-frame-hdr to ld To: Alistair Strachan , linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , "H. Peter Anvin" , X86 ML , Florian Weimer , Carlos O'Donell , "H. J. Lu" , Joel Fernandes , kernel-team@android.com References: <20181214222757.31280-1-astrachan@google.com> From: Laura Abbott Message-ID: <4ab89a22-90af-9e57-a35f-7b478d8c62d5@redhat.com> Date: Fri, 14 Dec 2018 14:32:06 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181214222757.31280-1-astrachan@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/18 2:27 PM, Alistair Strachan wrote: > 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: Laura Abbott You should probably use the bugzilla reporters instead of me given I just did the boring part of sending an e-mail. Instead you can use: Tested-by: Laura Abbott > Fixes: 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link") > Cc: stable@vger.kernel.org > Cc: Andy Lutomirski > Cc: Thomas Gleixner > Cc: "H. Peter Anvin" > Cc: X86 ML > Cc: Florian Weimer , > Cc: Carlos O'Donell , > Cc: "H. J. Lu" > Cc: Joel Fernandes > Cc: kernel-team@android.com > Signed-off-by: Alistair Strachan > --- > 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 > > # >