From: Ard Biesheuvel <ardb@kernel.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
Mark Rutland <mark.rutland@arm.com>,
Linux-Arch <linux-arch@vger.kernel.org>,
linux-efi <linux-efi@vger.kernel.org>,
Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Russell King <linux@armlinux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Ingo Molnar <mingo@redhat.com>, James Morse <james.morse@arm.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Borislav Petkov <bp@suse.de>,
Peter Collingbourne <pcc@google.com>,
Ingo Molnar <mingo@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v6 13/29] arm64/build: Assert for unwanted sections
Date: Tue, 27 Oct 2020 14:56:59 +0100 [thread overview]
Message-ID: <CAMj1kXEWJ8ZqerzVheWwT8zVT6MUivO+McyuF7tjHywWHyGnnQ@mail.gmail.com> (raw)
In-Reply-To: <CAMj1kXEdgOkH6VFa5_J6yqaJheToHUSM8jYXyGfA9JS5xwyLGQ@mail.gmail.com>
On Tue, 27 Oct 2020 at 12:29, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Tue, 27 Oct 2020 at 11:20, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> >
> > Hi Jean-Philippe,
> >
> > On Tue, Oct 27, 2020 at 11:09 AM Jean-Philippe Brucker
> > <jean-philippe@linaro.org> wrote:
> > > On Mon, Oct 26, 2020 at 06:38:46PM +0100, Ard Biesheuvel wrote:
> > > > > > > Note that even on plain be2881824ae9eb92, I get:
> > > > > > >
> > > > > > > aarch64-linux-gnu-ld: Unexpected GOT/PLT entries detected!
> > > > > > > aarch64-linux-gnu-ld: Unexpected run-time procedure linkages detected!
> > > > > > >
> > > > > > > The parent commit obviously doesn't show that (but probably still has
> > > > > > > the problem).
> > > > >
> > > > > Reverting both
> > > > > b3e5d80d0c48c0cc ("arm64/build: Warn on orphan section placement")
> > > > > be2881824ae9eb92 ("arm64/build: Assert for unwanted sections")
> > > > > seems to solve my problems, without any ill effects?
> > > > >
> > > >
> > > > I cannot reproduce the issue here with my distro GCC+binutils (Debian 8.3.0)
> > >
> > > I have the same problem with one of my debug configs and Linux v5.10-rc1,
> > > and can reproduce with the Debian 8.3.0 toolchain, by using the arm64
> > > defconfig and disabling CONFIG_MODULES:
> > >
> > > ld -EL -maarch64elf --no-undefined -X -z norelro -shared -Bsymbolic -z notext --no-apply-dynamic-relocs --fix-cortex-a53-843419 --orphan-handling=warn --build-id=sha1 --strip-debug -o .tmp_vmlinux.kallsyms1 -T ./arch/arm64/kernel/vmlinux.lds --whole-archive arch/arm64/kernel/head.o init/built-in.a usr/built-in.a arch/arm64/built-in.a kernel/built-in.a certs/built-in.a mm/built-in.a fs/built-in.a ipc/built-in.a security/built-in.a crypto/built-in.a block/built-in.a arch/arm64/lib/built-in.a lib/built-in.a drivers/built-in.a sound/built-in.a net/built-in.a virt/built-in.a --no-whole-archive --start-group arch/arm64/lib/lib.a lib/lib.a ./drivers/firmware/efi/libstub/lib.a --end-group
> > > ld: Unexpected GOT/PLT entries detected!
> > > ld: Unexpected run-time procedure linkages detected!
> > >
> > > Adding -fno-pie to this command doesn't fix the problem.
> > >
> > > Note that when cross-building with a GCC 10.2 and binutils 2.35.1 I also
> > > get several "aarch64-linux-gnu-ld: warning: -z norelro ignored" in
> > > addition to the error, but I don't get that warning with the 8.3.0
> > > toolchain.
> >
> > Thanks, my config (renesas_defconfig) also had CONFIG_MODULES disabled.
> > Enabling that fixes the link error due to unexpected entries, but the
> > .eh_frame orphan section warning is still there.
> >
>
> Looks like this is caused by the VFIO driver doing nasty things with
> symbol_get(), resulting in weak symbol references being emitted. Since
> taking the address of a weak symbol can yield NULL, the only way for
> the linker to accommodate this is to use GOT indirection for the
> direct symbol reference, so that the GOT entry can be set to NULL if
> the reference is not satisfied at link time.
This seems to do the trick for me.
diff --git a/include/linux/module.h b/include/linux/module.h
index 7ccdf87f376f..6264617bab4d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -740,7 +740,7 @@ static inline bool within_module(unsigned long
addr, const struct module *mod)
}
/* Get/put a kernel symbol (calls should be symmetric) */
-#define symbol_get(x) ({ extern typeof(x) x __attribute__((weak)); &(x); })
+#define symbol_get(x) ({ extern typeof(x) x
__attribute__((weak,visibility("hidden"))); &(x); })
#define symbol_put(x) do { } while (0)
#define symbol_put_addr(x) do { } while (0)
next prev parent reply other threads:[~2020-10-27 18:28 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 19:42 [PATCH v6 00/29] Warn on orphan section placement Kees Cook
2020-08-21 19:42 ` [PATCH v6 01/29] vmlinux.lds.h: Create COMMON_DISCARDS Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 02/29] vmlinux.lds.h: Add .gnu.version* to COMMON_DISCARDS Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 03/29] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 04/29] vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 05/29] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 06/29] vmlinux.lds.h: add PGO and AutoFDO input sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] vmlinux.lds.h: Add " tip-bot2 for Nick Desaulniers
2020-08-21 19:42 ` [PATCH v6 07/29] efi/libstub: Disable -mbranch-protection Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 08/29] arm64/mm: Remove needless section quotes Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 09/29] arm64/kernel: Remove needless Call Frame Information annotations Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 10/29] arm64/build: Remove .eh_frame* sections due to unwind tables Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 11/29] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 12/29] arm64/build: Add missing DWARF sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 13/29] arm64/build: Assert for unwanted sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-10-26 12:29 ` [PATCH v6 13/29] " Geert Uytterhoeven
2020-10-26 13:29 ` Geert Uytterhoeven
2020-10-26 16:01 ` Geert Uytterhoeven
2020-10-26 17:38 ` Ard Biesheuvel
2020-10-26 17:43 ` Geert Uytterhoeven
2020-10-26 17:48 ` Nick Desaulniers
2020-10-26 17:53 ` Geert Uytterhoeven
2020-10-27 8:37 ` Geert Uytterhoeven
2020-10-27 19:25 ` Geert Uytterhoeven
2020-10-27 19:33 ` Ard Biesheuvel
2020-10-27 20:00 ` Arvind Sankar
2020-10-27 20:12 ` Nick Desaulniers
2020-10-27 20:15 ` Ard Biesheuvel
2020-10-27 20:17 ` Nick Desaulniers
2020-10-27 20:30 ` Arvind Sankar
2020-10-27 20:40 ` Nick Desaulniers
2020-10-27 21:24 ` Arvind Sankar
2020-10-27 20:28 ` Nick Desaulniers
2020-10-27 20:32 ` Arvind Sankar
2020-10-27 20:36 ` Nick Desaulniers
2020-10-28 21:36 ` Alexei Starovoitov
2020-10-27 8:51 ` Geert Uytterhoeven
2020-10-27 10:08 ` Jean-Philippe Brucker
2020-10-27 10:20 ` Geert Uytterhoeven
2020-10-27 11:29 ` Ard Biesheuvel
2020-10-27 11:53 ` Naresh Kamboju
2020-10-27 13:56 ` Ard Biesheuvel [this message]
2020-08-21 19:42 ` [PATCH v6 14/29] arm64/build: Warn on orphan section placement Kees Cook
2020-08-21 19:42 ` [PATCH v6 15/29] arm/build: Refactor linker script headers Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 16/29] arm/build: Explicitly keep .ARM.attributes sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 17/29] arm/build: Add missing sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 18/29] arm/build: Assert for unwanted sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 19/29] arm/build: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` [PATCH v6 20/29] arm/boot: Handle all sections explicitly Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 21/29] arm/boot: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` [PATCH v6 22/29] x86/asm: Avoid generating unused kprobe sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 23/29] x86/build: Enforce an empty .got.plt section Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 24/29] x86/build: Assert for unwanted sections Kees Cook
2020-09-01 11:47 ` [tip: core/build] x86/build: Add asserts " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 25/29] x86/build: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` [PATCH v6 26/29] x86/boot/compressed: Reorganize zero-size section asserts Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 27/29] x86/boot/compressed: Remove, discard, or assert for unwanted sections Kees Cook
2020-08-21 20:01 ` Arvind Sankar
2020-08-21 21:21 ` Kees Cook
2020-08-21 21:28 ` Arvind Sankar
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 28/29] x86/boot/compressed: Add missing debugging sections to output Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 29/29] x86/boot/compressed: Warn on orphan section placement Kees Cook
2020-08-31 19:41 ` [PATCH v6 00/29] " Kees Cook
2020-09-01 7:11 ` Ingo Molnar
2020-09-01 7:59 ` Ingo Molnar
2020-09-01 8:16 ` Ingo Molnar
2020-09-01 15:17 ` Kees Cook
2020-09-01 18:02 ` Nick Desaulniers
2020-09-01 23:18 ` Kees Cook
2020-09-01 23:54 ` Nick Desaulniers
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