From: ndesaulniers@google.com
To: luto@kernel.org
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Fangrui Song <maskray@google.com>,
Andi Kleen <ak@linux.intel.com>, Andi Kleen <andi@firstfloor.org>,
Dmitry Golovin <dima@golovin.in>,
Bill Wendling <morbo@google.com>, Rui Ueyama <ruiu@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] x86/vdso: drop implicit common-page-size linker flag
Date: Thu, 6 Dec 2018 11:12:31 -0800 [thread overview]
Message-ID: <20181206191231.192355-1-ndesaulniers@google.com> (raw)
These are implied by the target architecture and for x86_64 match the
max-page-size. The default for non-NaCl x86_64 is 0x1000 (4096).
In bfd the common page size is defined as 0x1000 (4096) for non-NaCl
x86_64 targets:
bfd/elf64-x86-64.c:
4998:#define ELF_COMMONPAGESIZE 0x1000
For gold, the common page size is defined as 0x1000 (4096) for non-NaCl
x86_64 targets:
gold/x86_64.cc:
1413: 0x1000, // common_pagesize (overridable by -z common-page-size)
1442: 0x1000, // common_pagesize (overridable by -z common-page-size)
(ELF_COMMONPAGESIZE also defaults to ELF_MAXPAGESIZE when not set
explicitly for a target architecture in bfd/elfxx-target.h, but that's
not relevant for x86_64).
Because it's implied by the target architecture, it's of questionable
use to implement in LLD. This patch resolves one of the issues towards
using LLD to link an x86_64 kernel.
Fixes commit 2aae950b21e4 ("x86_64: Add vDSO for x86-64 with
gettimeofday/clock_gettime/getcpu")
Link: https://bugs.llvm.org/show_bug.cgi?id=38774
Link: https://github.com/ClangBuiltLinux/linux/issues/31
Cc: Fangrui Song <maskray@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Reported-by: Dmitry Golovin <dima@golovin.in>
Reported-by: Bill Wendling <morbo@google.com>
Suggested-by: Dmitry Golovin <dima@golovin.in>
Suggested-by: Rui Ueyama <ruiu@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/x86/entry/vdso/Makefile | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 141d415a8c80..0624bf2266fd 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -47,7 +47,7 @@ targets += $(vdso_img_sodbg) $(vdso_img-y:%=vdso%.so)
CPPFLAGS_vdso.lds += -P -C
VDSO_LDFLAGS_vdso.lds = -m elf_x86_64 -soname linux-vdso.so.1 --no-undefined \
- -z max-page-size=4096 -z common-page-size=4096
+ -z max-page-size=4096
$(obj)/vdso64.so.dbg: $(obj)/vdso.lds $(vobjs) FORCE
$(call if_changed,vdso)
@@ -98,7 +98,7 @@ CFLAGS_REMOVE_vvar.o = -pg
CPPFLAGS_vdsox32.lds = $(CPPFLAGS_vdso.lds)
VDSO_LDFLAGS_vdsox32.lds = -m elf32_x86_64 -soname linux-vdso.so.1 \
- -z max-page-size=4096 -z common-page-size=4096
+ -z max-page-size=4096
# x32-rebranded versions
vobjx32s-y := $(vobjs-y:.o=-x32.o)
--
2.20.0.rc1.387.gf8505762e3-goog
next reply other threads:[~2018-12-06 19:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-06 19:12 ndesaulniers [this message]
2018-12-06 20:29 ` [PATCH] x86/vdso: drop implicit common-page-size linker flag Andy Lutomirski
2018-12-07 10:18 ` Borislav Petkov
2018-12-07 17:45 ` Nick Desaulniers
2018-12-07 17:52 ` Borislav Petkov
2018-12-07 18:00 ` Nick Desaulniers
2018-12-07 18:33 ` [tip:x86/urgent] x86/vdso: Drop " tip-bot for Nick Desaulniers
2018-12-11 13:12 ` [tip:x86/build] x86/um/vdso: " tip-bot for ndesaulniers@google.com
2018-12-11 17:39 ` Nick Desaulniers
2018-12-11 17:43 ` Richard Weinberger
2018-12-11 17:46 ` Borislav Petkov
2018-12-11 17:53 ` Nick Desaulniers
2018-12-11 18:05 ` Borislav Petkov
2018-12-11 19:08 ` Nick Desaulniers
2018-12-11 20:14 ` Richard Weinberger
2018-12-11 20:53 ` Borislav Petkov
2018-12-11 13:25 ` tip-bot for Nick Desaulniers
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