On Wed, 2006-12-13 at 15:36 +1100, Rusty Russell wrote:
> 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.
And this variant traps kill instead which is simpler:
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.
Not tested on this particular assertion, but should work.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
diff -r 2d9ddfd41f3a arch/i386/Kconfig
--- a/arch/i386/Kconfig Wed Dec 13 16:04:20 2006 +1100
+++ b/arch/i386/Kconfig Wed Dec 13 16:04:21 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 2d9ddfd41f3a arch/i386/kernel/signal.c
--- a/arch/i386/kernel/signal.c Wed Dec 13 16:04:20 2006 +1100
+++ b/arch/i386/kernel/signal.c Wed Dec 13 16:20:32 2006 +1100
@@ -655,3 +655,22 @@ void do_notify_resume(struct pt_regs *re
clear_thread_flag(TIF_IRET);
}
+
+#ifdef CONFIG_COMPAT_VDSO
+#include <linux/syscalls.h>
+
+asmlinkage long
+sys_check_init_abort_kill(int pid, int sig)
+{
+ if (unlikely(current == child_reaper)
+ && pid == 1 && sig == SIGABRT && vdso_enabled) {
+ void reexec_init(void);
+ printk(KERN_WARNING "COMPAT_VDSO: Old glibc?"
+ " Re-execing init with vdso disabled\n");
+ vdso_enabled = 0;
+ reexec_init();
+ printk(KERN_WARNING "Re-exec of init failed\n");
+ }
+ return sys_kill(pid, sig);
+}
+#endif
diff -r 2d9ddfd41f3a arch/i386/kernel/syscall_table.S
--- a/arch/i386/kernel/syscall_table.S Wed Dec 13 16:04:20 2006 +1100
+++ b/arch/i386/kernel/syscall_table.S Wed Dec 13 16:06:44 2006 +1100
@@ -36,7 +36,11 @@ ENTRY(sys_call_table)
.long sys_nice
.long sys_ni_syscall /* 35 - old ftime syscall holder */
.long sys_sync
+#ifdef CONFIG_COMPAT_VDSO
+ .long sys_check_init_abort_kill
+#else
.long sys_kill
+#endif
.long sys_rename
.long sys_mkdir
.long sys_rmdir /* 40 */
diff -r 2d9ddfd41f3a arch/i386/kernel/sysenter.c
--- a/arch/i386/kernel/sysenter.c Wed Dec 13 16:04:20 2006 +1100
+++ b/arch/i386/kernel/sysenter.c Wed Dec 13 16:04:21 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 2d9ddfd41f3a arch/i386/mm/pgtable.c
--- a/arch/i386/mm/pgtable.c Wed Dec 13 16:04:20 2006 +1100
+++ b/arch/i386/mm/pgtable.c Wed Dec 13 16:04:21 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 2d9ddfd41f3a include/asm-i386/elf.h
--- a/include/asm-i386/elf.h Wed Dec 13 16:04:20 2006 +1100
+++ b/include/asm-i386/elf.h Wed Dec 13 16:04:21 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 2d9ddfd41f3a include/asm-i386/fixmap.h
--- a/include/asm-i386/fixmap.h Wed Dec 13 16:04:20 2006 +1100
+++ b/include/asm-i386/fixmap.h Wed Dec 13 16:04:21 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 2d9ddfd41f3a init/main.c
--- a/init/main.c Wed Dec 13 16:04:20 2006 +1100
+++ b/init/main.c Wed Dec 13 16:04:21 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();
