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SubjectRe: [Bugme-new] [Bug 7891] New: vdso page is no longer mapped for
Date
On Saturday 27 January 2007 23:02, Andrew Morton wrote:
> On Sat, 27 Jan 2007 15:01:51 -0500
>
> "Parag Warudkar" <parag.warudkar@gmail.com> wrote:
> > Here is a patch that does what Andrew Morton suggested (plus some more
> > as explained below) .
> > Patch inline below and also attached in case there is whitespace
> > damage. Compile tested on i386 with make defconfig; make. If anyone
> > can test on other arches and provide feedback that'd be great.
>
> Thanks - I can test elf on powerpc. Does anyone remember how to
> create a.out executables?

You need an old toolkit, but the historic section of ftp.funet.fi
has a few binaries. I also got a tarball of an old a.out SUSE
installation somewhere that I can dig out if there is interest.

> Assuming this works, I'm not surew what to do with it. Jam it into
> 2.6.20, I guess. The lateness*largeness product is somewhat high though.

I simpler fix might be to just not require the vDSO for signal handling
on a.out.

Here's a untested patch.

-Andi

Don't require the vDSO for handling a.out signals

and in other strange binfmts. vDSO is not necessarily mapped there.

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/i386/kernel/signal.c
===================================================================
--- linux.orig/arch/i386/kernel/signal.c
+++ linux/arch/i386/kernel/signal.c
@@ -21,6 +21,7 @@
#include <linux/suspend.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
+#include <linux/binfmts.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
@@ -349,7 +350,10 @@ static int setup_frame(int sig, struct k
goto give_sigsegv;
}

- restorer = (void *)VDSO_SYM(&__kernel_sigreturn);
+ if (current->binfmt->hasvdso)
+ restorer = (void *)VDSO_SYM(&__kernel_sigreturn);
+ else
+ restorer = (void *)&frame->retcode;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;

Index: linux/arch/x86_64/ia32/ia32_signal.c
===================================================================
--- linux.orig/arch/x86_64/ia32/ia32_signal.c
+++ linux/arch/x86_64/ia32/ia32_signal.c
@@ -21,6 +21,7 @@
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compat.h>
+#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
@@ -449,7 +450,11 @@ int ia32_setup_frame(int sig, struct k_s

/* Return stub is in 32bit vsyscall page */
{
- void __user *restorer = VSYSCALL32_SIGRETURN;
+ void __user *restorer;
+ if (current->binfmt->hasvdso)
+ restorer = VSYSCALL32_SIGRETURN;
+ else
+ restorer = (void *)&frame->retcode;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
err |= __put_user(ptr_to_compat(restorer), &frame->pretcode);
Index: linux/fs/binfmt_elf.c
===================================================================
--- linux.orig/fs/binfmt_elf.c
+++ linux/fs/binfmt_elf.c
@@ -76,7 +76,8 @@ static struct linux_binfmt elf_format =
.load_binary = load_elf_binary,
.load_shlib = load_elf_library,
.core_dump = elf_core_dump,
- .min_coredump = ELF_EXEC_PAGESIZE
+ .min_coredump = ELF_EXEC_PAGESIZE,
+ .hasvdso = 1
};

#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
Index: linux/include/linux/binfmts.h
===================================================================
--- linux.orig/include/linux/binfmts.h
+++ linux/include/linux/binfmts.h
@@ -59,6 +59,7 @@ struct linux_binfmt {
int (*load_shlib)(struct file *);
int (*core_dump)(long signr, struct pt_regs * regs, struct file * file);
unsigned long min_coredump; /* minimal dump size */
+ int hasvdso;
};

extern int register_binfmt(struct linux_binfmt *);
-
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