linux-toradex.git/arch/um/sys-x86_64, branch v3.0.19

uml: kernels on {i386,x86_64} produce bad coredumps

2011-03-23T00:44:09+00:00

One of our users reported that when a user-level program SIGSEGVs under
UML kernel, the resulting core dump is not very usable.

I have reproduced that with the latest kernel:

  make ARCH=um defconfig; make ARCH=um

Run the resulting kernel, then "inside" run this program:

#include 

void *fn(void *p)
{
 abort();
}

int main()
{
 pthread_t tid;
 pthread_create(&tid, 0, fn, 0);
 pthread_join(tid, 0);
 return 0;
}

Analyze the coredump with GDB. Here is what you'll see:

sudo gdb -q -ex 'set solib-absolute-prefix ../root_fs' -ex 'file ../root_fs/var/tmp/mt-abort' -ex 'core ../root_fs/var/tmp/core.762'
Reading symbols from /usr/local/google/root_fs/var/tmp/mt-abort...done.
[New Thread 763]
[New Thread 762]
Core was generated by `./mt-abort'.
Program terminated with signal 6, Aborted.
#0  0x0000000040255250 in raise () from ../root_fs/lib64/libc.so.6
(gdb) info thread
  2 Thread 762  0x0000000000000000 in ?? ()
* 1 Thread 763  0x0000000040255250 in raise () from ../root_fs/lib64/libc.so.6

Note that thread#2 looks funny.

(gdb) thread 2
[Switching to thread 2 (Thread 762)]#0  0x0000000000000000 in ?? ()
(gdb) info reg
rax            0x0      0
rbx            0x0      0
rcx            0x0      0
rdx            0x0      0
rsi            0x0      0
rdi            0x0      0
rbp            0x0      0x0
rsp            0x0      0x0
r8             0x0      0
r9             0x0      0
r10            0x0      0
r11            0x0      0
r12            0x0      0
r13            0x0      0
r14            0x0      0
r15            0x0      0
rip            0x0      0
eflags         0x0      [ ]
cs             0x0      0
ss             0x0      0
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0

Examining the core shows that NT_PRSTATUS notes for all threads other than
the one that crashed are zeroed out.

I believe this is happening because neither ELF_CORE_COPY_TASK_REGS nor
task_pt_regs are defined under ARCH=um, and so elf_core_copy_task_regs()
becomes a no-op.

Attached patch fixes this for SUBARCH={x86_64,i386}.

Signed-off-by: Paul Pluzhnikov 
Cc: Jeff Dike 
Acked-by: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ptrace: cleanup arch_ptrace() on um

2010-10-28T01:03:12+00:00

Remove unnecessary castings using void pointer and fix copy_to_user()
return value. Also add missing __user markup on the argument of
arch_ptrctl().

Signed-off-by: Namhyung Kim 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ptrace: change signature of arch_ptrace()

2010-10-28T01:03:10+00:00

Fix up the arguments to arch_ptrace() to take account of the fact that
@addr and @data are now unsigned long rather than long as of a preceding
patch in this series.

Signed-off-by: Namhyung Kim 
Cc: 
Acked-by: Roland McGrath 
Acked-by: David Howells 
Acked-by: Geert Uytterhoeven 
Acked-by: David S. Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

UML: Fix compiler warning due to missing task_struct declaration

2010-04-20T23:43:03+00:00

We can't pull in linux/sched.h due to circular dependency, so just
forward-declare the struct.

This fixes the following warning:

  CC      arch/um/sys-i386/elfcore.o
In file included from /data/linux-2.6/include/linux/elf.h:8,
                 from /data/linux-2.6/arch/um/sys-i386/elfcore.c:2:
arch/um/sys-i386/asm/elf.h:78: warning: ‘struct task_struct’ declared inside parameter list
arch/um/sys-i386/asm/elf.h:78: warning: its scope is only this definition or declaration, which is probably not what you want

I guess not many people build against i386 hosts anymore, so this
remained widely unnoticed.

Signed-off-by: Jan Kiszka 
Signed-off-by: Jiri Kosina

UML: add kernel.h include to signal.c

2010-04-20T15:47:24+00:00

Commit 814f75ec5a94a48 ("UML: Drop private round_down definition") dropped
the private round_down() macro and makes signal.c use the one from kernel.h
instead.

kernel.h is implicitly included through uaccess.h -> sched.h -> kernel.h
but we'd rather make this dependency explicit.

Signed-off-by: Jiri Kosina

UML: Drop private round_down definition

2010-04-20T14:36:35+00:00

Already defined in kernel.h. The official version assumes that 'n' is
power of two - which it is in our case.

Signed-off-by: Jan Kiszka 
Signed-off-by: Jiri Kosina

improve sys_newuname() for compat architectures

2010-03-12T23:52:32+00:00

On an architecture that supports 32-bit compat we need to override the
reported machine in uname with the 32-bit value.  Instead of doing this
separately in every architecture introduce a COMPAT_UTS_MACHINE define in
 and apply it directly in sys_newuname().

Signed-off-by: Christoph Hellwig 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mundt 
Cc: Jeff Dike 
Cc: Hirokazu Takata 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: H. Peter Anvin 
Cc: Al Viro 
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: "Luck, Tony" 
Cc: James Morris 
Cc: Andreas Schwab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86: Fix breakage of UML from the changes in the rwsem system

2010-01-18T05:51:29+00:00

The patches 5d0b7235d83eefdafda300656e97d368afcafc9a and
bafaecd11df15ad5b1e598adc7736afcd38ee13d broke the UML build:

On Sun, 17 Jan 2010, Ingo Molnar wrote:
>
> FYI, -tip testing found that these changes break the UML build:
>
> kernel/built-in.o: In function `__up_read':
> /home/mingo/tip/arch/x86/include/asm/rwsem.h:192: undefined reference to `call_rwsem_wake'
> kernel/built-in.o: In function `__up_write':
> /home/mingo/tip/arch/x86/include/asm/rwsem.h:210: undefined reference to `call_rwsem_wake'
> kernel/built-in.o: In function `__downgrade_write':
> /home/mingo/tip/arch/x86/include/asm/rwsem.h:228: undefined reference to `call_rwsem_downgrade_wake'
> kernel/built-in.o: In function `__down_read':
> /home/mingo/tip/arch/x86/include/asm/rwsem.h:112: undefined reference to `call_rwsem_down_read_failed'
> kernel/built-in.o: In function `__down_write_nested':
> /home/mingo/tip/arch/x86/include/asm/rwsem.h:154: undefined reference to `call_rwsem_down_write_failed'
> collect2: ld returned 1 exit status

Add lib/rwsem_64.o to the UML subarch objects to fix.

LKML-Reference: 
Signed-off-by: H. Peter Anvin

elf: kill USE_ELF_CORE_DUMP

2009-12-16T15:20:12+00:00

Currently all architectures but microblaze unconditionally define
USE_ELF_CORE_DUMP.  The microblaze omission seems like an error to me, so
let's kill this ifdef and make sure we are the same everywhere.

Signed-off-by: Christoph Hellwig 
Acked-by: Hugh Dickins 
Cc: 
Cc: Michal Simek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: bad macro expansion, parameter is member

2009-06-17T02:47:47+00:00

`ELF_CORE_COPY_REGS(x, y)' will make expansions like:
`(y)[0] = (x)->x.gp[0]' but correct is `(y)[0] = (x)->regs.gp[0]'

Signed-off-by: Roel Kluin 
Cc: WANG Cong 
Cc: Jeff Dike 

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds