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parisc: fix ptrace breakage

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1) PTRACE_SYSCALL doesn't work for 64bit process on parisc64.
Compat syscall table is used instead of 64bit one.  IMO we should either
refuse to allow PTRACE_SYSCALL for 64bit processes or duplicate the
logics choosing the right syscall table into .Ltracesys.

	2) if you have let the tracee run with PTRACE_SYSCALL and
it had stopped, you can use PTRACE_POKEUSR to modify syscall number
(r20) and arguments 1--4 (r26--r23).  Modifications will have effect.
However, modifying arguments 5 and 6 (r22 and r21 resp.) works only
when process (32bit one) runs on 64bit host - on 32bit one it has no
effect.  AFAICS, the diff below should fix that one.

Signed-off-by: Al Viro <viro@ZenIV.linux.org.uk>
Tested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Al Viro 2012-12-09 06:16:14 +00:00 committed by Helge Deller
parent 872420b3b8
commit 52ab532ea7
1 changed files with 4 additions and 1 deletions
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5
arch/parisc/kernel/syscall.S
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@ -309,10 +309,13 @@ tracesys_next:
LDREG TASK_PT_GR25(%r1), %r25
LDREG TASK_PT_GR24(%r1), %r24
LDREG TASK_PT_GR23(%r1), %r23
#ifdef CONFIG_64BIT
LDREG TASK_PT_GR22(%r1), %r22
LDREG TASK_PT_GR21(%r1), %r21
#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
#else
stw %r22, -52(%r30) /* 5th argument */
stw %r21, -56(%r30) /* 6th argument */
#endif
comiclr,>>= __NR_Linux_syscalls, %r20, %r0