diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-03-14 03:01:26 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2014-03-14 03:20:09 +0400 |
| commit | b0b49f2673f011cad7deeabf7a683b388c351278 (patch) | |
| tree | 2a3bfe9ccc51d4b2072381fe4ebd4f3630a38444 /arch/x86/Kconfig | |
| parent | fa389e220254c69ffae0d403eac4146171062d08 (diff) | |
| download | linux-b0b49f2673f011cad7deeabf7a683b388c351278.tar.xz | |
x86, vdso: Remove compat vdso support
The compat vDSO is a complicated hack that's needed to maintain
compatibility with a small range of glibc versions.
This removes it and replaces it with a much simpler hack: a config
option to disable the 32-bit vDSO by default.
This also changes the default value of CONFIG_COMPAT_VDSO to n --
users configuring kernels from scratch almost certainly want that
choice.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0af5250d914f..9122f6bcbe45 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1836,17 +1836,29 @@ config DEBUG_HOTPLUG_CPU0 If unsure, say N. config COMPAT_VDSO - def_bool y - prompt "Compat VDSO support" + def_bool n + prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" depends on X86_32 || IA32_EMULATION ---help--- - Map the 32-bit VDSO to the predictable old-style address too. + Certain buggy versions of glibc will crash if they are + presented with a 32-bit vDSO that is not mapped at the address + indicated in its segment table. - Say N here if you are running a sufficiently recent glibc - version (2.3.3 or later), to remove the high-mapped - VDSO mapping and to exclusively use the randomized VDSO. + The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a + and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and + 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is + the only released version with the bug, but OpenSUSE 9 + contains a buggy "glibc 2.3.2". - If unsure, say Y. + The symptom of the bug is that everything crashes on startup, saying: + dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! + + Saying Y here changes the default value of the vdso32 boot + option from 1 to 0, which turns off the 32-bit vDSO entirely. + This works around the glibc bug but hurts performance. + + If unsure, say N: if you are compiling your own kernel, you + are unlikely to be using a buggy version of glibc. config CMDLINE_BOOL bool "Built-in kernel command line" |