redonkable/alistair23-linux
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Blackfin: simplify SYSCFG code a bit and ignore attempts to change it

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We don't want to let user space modify the SYSCFG register arbitrarily as
the settings are system wide (SNEN/CNEN) and can cause misbehavior.  The
only other bit here (SSSTEP) has proper controls via PTRACE_SINGLESTEP.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This commit is contained in:
Mike Frysinger 2010-02-14 22:49:59 +00:00
parent f5b99627a3
commit 5f09c77d2a
1 changed files with 6 additions and 18 deletions
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24
arch/blackfin/kernel/ptrace.c
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@ -31,12 +31,6 @@
* in exit.c or in signal.c.
*/
/* determines which bits in the SYSCFG reg the user has access to. */
/* 1 = access 0 = no access */
#define SYSCFG_MASK 0x0007 /* SYSCFG reg */
/* sets the trace bits. */
#define TRACE_BITS 0x0001
/* Find the stack offset for a register, relative to thread.esp0. */
#define PT_REG(reg) ((long)&((struct pt_regs *)0)->reg)
@ -162,9 +156,8 @@ static inline int is_user_addr_valid(struct task_struct *child,
void ptrace_enable(struct task_struct *child)
{
unsigned long tmp;
tmp = get_reg(child, PT_SYSCFG) | (TRACE_BITS);
put_reg(child, PT_SYSCFG, tmp);
struct pt_regs *regs = task_pt_regs(child);
regs->syscfg |= SYSCFG_SSSTEP;
}
/*
@ -174,10 +167,8 @@ void ptrace_enable(struct task_struct *child)
*/
void ptrace_disable(struct task_struct *child)
{
unsigned long tmp;
/* make sure the single step bit is not set. */
tmp = get_reg(child, PT_SYSCFG) & ~TRACE_BITS;
put_reg(child, PT_SYSCFG, tmp);
struct pt_regs *regs = task_pt_regs(child);
regs->syscfg &= ~SYSCFG_SSSTEP;
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
@ -343,14 +334,11 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
break;
}
if (addr >= (sizeof(struct pt_regs))) {
/* Ignore writes to SYSCFG and other pseudo regs */
if (addr >= PT_SYSCFG) {
ret = 0;
break;
}
if (addr == PT_SYSCFG) {
data &= SYSCFG_MASK;
data |= get_reg(child, PT_SYSCFG);
}
ret = put_reg(child, addr, data);
break;