linux/include/asm-s390/user.h
Bodo Stroesser c5c3a6d8fe [PATCH] s390: uml ptrace fixes
To make UML build and run on s390, I needed to do these two little
changes:

1) UML includes some of the subarch's (s390) headers. I had to
   change one of them with the following one-liner, to make this
   compile. AFAICS, this change doesn't break compilation of s390
   itself.

2) UML needs to intercept syscalls via ptrace to invalidate the syscall,
   read syscall's parameters and write the result with the result of
   UML's syscall processing. Also, UML needs to make sure, that the host
   does no syscall restart processing. On i386 for example, this can be
   done by writing -1 to orig_eax on the 2nd syscall interception
   (orig_eax is the syscall number, which after the interception is used
   as a "interrupt was a syscall" flag only.
   Unfortunately, s390 holds syscall number and syscall result in gpr2 and
   its "interrupt was a syscall" flag (trap) is unreachable via ptrace.
   So I changed the host to set trap to -1, if the syscall number is changed
   to an invalid value on the first syscall interception.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-04 17:13:00 -07:00

77 lines
3.3 KiB
C

/*
* include/asm-s390/user.h
*
* S390 version
*
* Derived from "include/asm-i386/usr.h"
*/
#ifndef _S390_USER_H
#define _S390_USER_H
#include <asm/page.h>
#include <asm/ptrace.h>
/* Core file format: The core file is written in such a way that gdb
can understand it and provide useful information to the user (under
linux we use the 'trad-core' bfd). There are quite a number of
obstacles to being able to view the contents of the floating point
registers, and until these are solved you will not be able to view the
contents of them. Actually, you can read in the core file and look at
the contents of the user struct to find out what the floating point
registers contain.
The actual file contents are as follows:
UPAGE: 1 page consisting of a user struct that tells gdb what is present
in the file. Directly after this is a copy of the task_struct, which
is currently not used by gdb, but it may come in useful at some point.
All of the registers are stored as part of the upage. The upage should
always be only one page.
DATA: The data area is stored. We use current->end_text to
current->brk to pick up all of the user variables, plus any memory
that may have been malloced. No attempt is made to determine if a page
is demand-zero or if a page is totally unused, we just cover the entire
range. All of the addresses are rounded in such a way that an integral
number of pages is written.
STACK: We need the stack information in order to get a meaningful
backtrace. We need to write the data from (esp) to
current->start_stack, so we round each of these off in order to be able
to write an integer number of pages.
The minimum core file size is 3 pages, or 12288 bytes.
*/
/*
* This is the old layout of "struct pt_regs", and
* is still the layout used by user mode (the new
* pt_regs doesn't have all registers as the kernel
* doesn't use the extra segment registers)
*/
/* When the kernel dumps core, it starts by dumping the user struct -
this will be used by gdb to figure out where the data and stack segments
are within the file, and what virtual addresses to use. */
struct user {
/* We start with the registers, to mimic the way that "memory" is returned
from the ptrace(3,...) function. */
struct user_regs_struct regs; /* Where the registers are actually stored */
/* The rest of this junk is to help gdb figure out what goes where */
unsigned long int u_tsize; /* Text segment size (pages). */
unsigned long int u_dsize; /* Data segment size (pages). */
unsigned long int u_ssize; /* Stack segment size (pages). */
unsigned long start_code; /* Starting virtual address of text. */
unsigned long start_stack; /* Starting virtual address of stack area.
This is actually the bottom of the stack,
the top of the stack is always found in the
esp register. */
long int signal; /* Signal that caused the core dump. */
struct user_regs_struct *u_ar0;
/* Used by gdb to help find the values for */
/* the registers. */
unsigned long magic; /* To uniquely identify a core file */
char u_comm[32]; /* User command that was responsible */
};
#define NBPG PAGE_SIZE
#define UPAGES 1
#define HOST_TEXT_START_ADDR (u.start_code)
#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * NBPG)
#endif /* _S390_USER_H */