Commit 52ab532e authored Dec 09, 2012 by Al Viro Committed by Helge Deller Feb 20, 2013

parisc: fix ptrace breakage



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>

parent 872420b3

arch/parisc/kernel/syscall.S

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -309,10 +309,13 @@ tracesys_next:
	LDREG TASK_PT_GR25(%r1), %r25		LDREG TASK_PT_GR25(%r1), %r25
	LDREG TASK_PT_GR24(%r1), %r24		LDREG TASK_PT_GR24(%r1), %r24
	LDREG TASK_PT_GR23(%r1), %r23		LDREG TASK_PT_GR23(%r1), %r23
	#ifdef CONFIG_64BIT
	LDREG TASK_PT_GR22(%r1), %r22		LDREG TASK_PT_GR22(%r1), %r22
	LDREG TASK_PT_GR21(%r1), %r21		LDREG TASK_PT_GR21(%r1), %r21
			#ifdef CONFIG_64BIT
	ldo -16(%r30),%r29 /* Reference param save area */		ldo -16(%r30),%r29 /* Reference param save area */
			#else
			stw %r22, -52(%r30) /* 5th argument */
			stw %r21, -56(%r30) /* 6th argument */
	#endif		#endif

	comiclr,>>= __NR_Linux_syscalls, %r20, %r0		comiclr,>>= __NR_Linux_syscalls, %r20, %r0