On Tue, 2006-12-12 at 22:15 +0100, Andi Kleen wrote:
> The failure is an assertation failure in ld.so.
OK, this patch tested on an assert() in init.
===
Older glibcs assert() that the vdso will be in a particular spot
(which it can no longer be with CONFIG_PARAVIRT). As this glibc was
shipped in SuSE 9.0 and Fedora Core 1, it's not a trivial breakage.
Try to detect the failing init at runtime, turn off vdso and re-exec.
Untested on the actual failing systems, but should work.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
diff -r ed1ffbd17965 arch/i386/Kconfig
--- a/arch/i386/Kconfig Wed Dec 13 14:11:14 2006 +1100
+++ b/arch/i386/Kconfig Wed Dec 13 14:30:30 2006 +1100
@@ -816,15 +816,14 @@ config HOTPLUG_CPU
/sys/devices/system/cpu.
config COMPAT_VDSO
- bool "Compat VDSO support"
- default y
- depends on !PARAVIRT
- help
- Map the VDSO to the predictable old-style address too.
- ---help---
- 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.
+ bool "Disable VDSO for old glibc"
+ default y
+ ---help---
+ Old glibc does not like the modern VDSO placement (glibc
+ 2.3.3 or later is fine, Fedora Core 1 and SuSE 9.0 have
+ problems). Very old glibc versions don't use the VDSO at
+ all. This option tries to detect the glibc assertion which
+ occurs and then disables the VDSO.
If unsure, say Y.
diff -r ed1ffbd17965 arch/i386/kernel/signal.c
--- a/arch/i386/kernel/signal.c Wed Dec 13 14:11:14 2006 +1100
+++ b/arch/i386/kernel/signal.c Wed Dec 13 15:26:37 2006 +1100
@@ -608,6 +608,20 @@ static void fastcall do_signal(struct pt
return;
}
+#ifdef CONFIG_COMPAT_VDSO
+ else if (signr == -1) {
+ void reexec_init(void);
+ if (vdso_enabled) {
+ printk(KERN_WARNING "COMPAT_VDSO: Old glibc?"
+ " Re-execing init with vdso disabled\n");
+ vdso_enabled = 0;
+ /* kill() made us think we're dying: we're not. */
+ current->signal->group_stop_count = 0;
+ reexec_init();
+ printk(KERN_WARNING "Re-exec of init failed\n");
+ }
+ }
+#endif
/* Did we come from a system call? */
if (regs->orig_eax >= 0) {
diff -r ed1ffbd17965 arch/i386/kernel/sysenter.c
--- a/arch/i386/kernel/sysenter.c Wed Dec 13 14:11:14 2006 +1100
+++ b/arch/i386/kernel/sysenter.c Wed Dec 13 14:13:35 2006 +1100
@@ -27,11 +27,7 @@
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
*/
-#ifdef CONFIG_PARAVIRT
-unsigned int __read_mostly vdso_enabled = 0;
-#else
unsigned int __read_mostly vdso_enabled = 1;
-#endif
EXPORT_SYMBOL_GPL(vdso_enabled);
@@ -76,15 +72,10 @@ int __init sysenter_setup(void)
{
syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
-#ifdef CONFIG_COMPAT_VDSO
- __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY);
- printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
-#else
/*
* In the non-compat case the ELF coredumping code needs the fixmap:
*/
__set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_KERNEL_RO);
-#endif
if (!boot_cpu_has(X86_FEATURE_SEP)) {
memcpy(syscall_page,
diff -r ed1ffbd17965 arch/i386/mm/pgtable.c
--- a/arch/i386/mm/pgtable.c Wed Dec 13 14:11:14 2006 +1100
+++ b/arch/i386/mm/pgtable.c Wed Dec 13 14:30:33 2006 +1100
@@ -144,10 +144,8 @@ void set_pmd_pfn(unsigned long vaddr, un
}
static int fixmaps;
-#ifndef CONFIG_COMPAT_VDSO
unsigned long __FIXADDR_TOP = 0xfffff000;
EXPORT_SYMBOL(__FIXADDR_TOP);
-#endif
void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
{
@@ -171,12 +169,8 @@ void reserve_top_address(unsigned long r
void reserve_top_address(unsigned long reserve)
{
BUG_ON(fixmaps > 0);
-#ifdef CONFIG_COMPAT_VDSO
- BUG_ON(reserve != 0);
-#else
__FIXADDR_TOP = -reserve - PAGE_SIZE;
__VMALLOC_RESERVE += reserve;
-#endif
}
pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
diff -r ed1ffbd17965 include/asm-i386/elf.h
--- a/include/asm-i386/elf.h Wed Dec 13 14:11:14 2006 +1100
+++ b/include/asm-i386/elf.h Wed Dec 13 14:11:14 2006 +1100
@@ -135,13 +135,8 @@ extern int dump_task_extended_fpu (struc
#define VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO))
#define VDSO_BASE ((unsigned long)current->mm->context.vdso)
-#ifdef CONFIG_COMPAT_VDSO
-# define VDSO_COMPAT_BASE VDSO_HIGH_BASE
-# define VDSO_PRELINK VDSO_HIGH_BASE
-#else
# define VDSO_COMPAT_BASE VDSO_BASE
# define VDSO_PRELINK 0
-#endif
#define VDSO_COMPAT_SYM(x) \
(VDSO_COMPAT_BASE + (unsigned long)(x) - VDSO_PRELINK)
diff -r ed1ffbd17965 include/asm-i386/fixmap.h
--- a/include/asm-i386/fixmap.h Wed Dec 13 14:11:14 2006 +1100
+++ b/include/asm-i386/fixmap.h Wed Dec 13 14:11:14 2006 +1100
@@ -19,11 +19,7 @@
* Leave one empty page between vmalloc'ed areas and
* the start of the fixmap.
*/
-#ifndef CONFIG_COMPAT_VDSO
extern unsigned long __FIXADDR_TOP;
-#else
-#define __FIXADDR_TOP 0xfffff000
-#endif
#ifndef __ASSEMBLY__
#include <linux/kernel.h>
diff -r ed1ffbd17965 init/main.c
--- a/init/main.c Wed Dec 13 14:11:14 2006 +1100
+++ b/init/main.c Wed Dec 13 15:31:57 2006 +1100
@@ -710,6 +710,16 @@ static void run_init_process(char *init_
kernel_execve(init_filename, argv_init, envp_init);
}
+#ifdef CONFIG_COMPAT_VDSO
+void reexec_init(void)
+{
+ mm_segment_t oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ kernel_execve(argv_init[0], argv_init, envp_init);
+ set_fs(oldfs);
+}
+#endif
+
static int init(void * unused)
{
lock_kernel();
diff -r ed1ffbd17965 kernel/signal.c
--- a/kernel/signal.c Wed Dec 13 14:11:14 2006 +1100
+++ b/kernel/signal.c Wed Dec 13 14:55:07 2006 +1100
@@ -1878,8 +1878,17 @@ relock:
continue;
/* Init gets no signals it doesn't want. */
- if (current == child_reaper)
+ if (current == child_reaper) {
+#ifdef CONFIG_COMPAT_VDSO
+ /* Gross hack: Old glibc asserts, not
+ liking moved vdso (SuSE 9, FC1) */
+ if (signr == SIGABRT) {
+ signr = -1;
+ break;
+ }
+#endif
continue;
+ }
if (sig_kernel_stop(signr)) {
/*
