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linux-next/arch/microblaze/kernel/ptrace.c

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/*
* `ptrace' system call
*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2007-2009 PetaLogix
* Copyright (C) 2004-2007 John Williams <john.williams@petalogix.com>
*
* derived from arch/v850/kernel/ptrace.c
*
* Copyright (C) 2002,03 NEC Electronics Corporation
* Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
*
* Derived from arch/mips/kernel/ptrace.c:
*
* Copyright (C) 1992 Ross Biro
* Copyright (C) Linus Torvalds
* Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
* Copyright (C) 1996 David S. Miller
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999 MIPS Technologies, Inc.
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file COPYING in the main directory of this
* archive for more details.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <linux/elf.h>
#include <linux/audit.h>
#include <linux/seccomp.h>
#include <linux/tracehook.h>
#include <linux/errno.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/syscall.h>
#include <asm/io.h>
/* Returns the address where the register at REG_OFFS in P is stashed away. */
static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
struct task_struct *t)
{
struct pt_regs *regs;
/*
* Three basic cases:
*
* (1) A register normally saved before calling the scheduler, is
* available in the kernel entry pt_regs structure at the top
* of the kernel stack. The kernel trap/irq exit path takes
* care to save/restore almost all registers for ptrace'd
* processes.
*
* (2) A call-clobbered register, where the process P entered the
* kernel via [syscall] trap, is not stored anywhere; that's
* OK, because such registers are not expected to be preserved
* when the trap returns anyway (so we don't actually bother to
* test for this case).
*
* (3) A few registers not used at all by the kernel, and so
* normally never saved except by context-switches, are in the
* context switch state.
*/
/* Register saved during kernel entry (or not available). */
regs = task_pt_regs(t);
return (microblaze_reg_t *)((char *)regs + reg_offs);
}
long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data)
{
int rval;
unsigned long val = 0;
switch (request) {
/* Read/write the word at location ADDR in the registers. */
case PTRACE_PEEKUSR:
case PTRACE_POKEUSR:
pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
rval = 0;
if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
/*
* Special requests that don't actually correspond
* to offsets in struct pt_regs.
*/
if (addr == PT_TEXT_ADDR) {
val = child->mm->start_code;
} else if (addr == PT_DATA_ADDR) {
val = child->mm->start_data;
} else if (addr == PT_TEXT_LEN) {
val = child->mm->end_code
- child->mm->start_code;
} else {
rval = -EIO;
}
} else if (addr < PT_SIZE && (addr & 0x3) == 0) {
microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
if (request == PTRACE_PEEKUSR)
val = *reg_addr;
else {
#if 1
*reg_addr = data;
#else
/* MS potential problem on WB system
* Be aware that reg_addr is virtual address
* virt_to_phys conversion is necessary.
* This could be sensible solution.
*/
u32 paddr = virt_to_phys((u32)reg_addr);
invalidate_icache_range(paddr, paddr + 4);
*reg_addr = data;
flush_dcache_range(paddr, paddr + 4);
#endif
}
} else
rval = -EIO;
if (rval == 0 && request == PTRACE_PEEKUSR)
rval = put_user(val, (unsigned long __user *)data);
break;
default:
rval = ptrace_request(child, request, addr, data);
}
return rval;
}
asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
long ret = 0;
secure_computing_strict(regs->r12);
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
tracehook_report_syscall_entry(regs))
/*
* Tracing decided this syscall should not happen.
* We'll return a bogus call number to get an ENOSYS
* error, but leave the original number in regs->regs[0].
*/
ret = -1L;
audit_syscall_entry(EM_MICROBLAZE, regs->r12, regs->r5, regs->r6,
regs->r7, regs->r8);
return ret ?: regs->r12;
}
asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
{
int step;
Audit: push audit success and retcode into arch ptrace.h The audit system previously expected arches calling to audit_syscall_exit to supply as arguments if the syscall was a success and what the return code was. Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things by converting from negative retcodes to an audit internal magic value stating success or failure. This helper was wrong and could indicate that a valid pointer returned to userspace was a failed syscall. The fix is to fix the layering foolishness. We now pass audit_syscall_exit a struct pt_reg and it in turns calls back into arch code to collect the return value and to determine if the syscall was a success or failure. We also define a generic is_syscall_success() macro which determines success/failure based on if the value is < -MAX_ERRNO. This works for arches like x86 which do not use a separate mechanism to indicate syscall failure. We make both the is_syscall_success() and regs_return_value() static inlines instead of macros. The reason is because the audit function must take a void* for the regs. (uml calls theirs struct uml_pt_regs instead of just struct pt_regs so audit_syscall_exit can't take a struct pt_regs). Since the audit function takes a void* we need to use static inlines to cast it back to the arch correct structure to dereference it. The other major change is that on some arches, like ia64, MIPS and ppc, we change regs_return_value() to give us the negative value on syscall failure. THE only other user of this macro, kretprobe_example.c, won't notice and it makes the value signed consistently for the audit functions across all archs. In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old audit code as the return value. But the ptrace_64.h code defined the macro regs_return_value() as regs[3]. I have no idea which one is correct, but this patch now uses the regs_return_value() function, so it now uses regs[3]. For powerpc we previously used regs->result but now use the regs_return_value() function which uses regs->gprs[3]. regs->gprs[3] is always positive so the regs_return_value(), much like ia64 makes it negative before calling the audit code when appropriate. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: H. Peter Anvin <hpa@zytor.com> [for x86 portion] Acked-by: Tony Luck <tony.luck@intel.com> [for ia64] Acked-by: Richard Weinberger <richard@nod.at> [for uml] Acked-by: David S. Miller <davem@davemloft.net> [for sparc] Acked-by: Ralf Baechle <ralf@linux-mips.org> [for mips] Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [for ppc]
2012-01-04 03:23:06 +08:00
audit_syscall_exit(regs);
step = test_thread_flag(TIF_SINGLESTEP);
if (step || test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(regs, step);
}
#if 0
static asmlinkage void syscall_trace(void)
{
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return;
if (!(current->ptrace & PT_PTRACED))
return;
/* The 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (current->exit_code) {
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
#endif
void ptrace_disable(struct task_struct *child)
{
/* nothing to do */
}