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m68k: switch to generic sys_execve()/kernel_execve() 

The tricky part here is that task_pt_regs() on m68k works *only* for
process inside do_signal().  However, we need something much simpler -
pt_regs of a process inside do_signal() may be at different offsets
from the stack bottom, depending on the way we'd entered the kernel,
but for a task inside sys_execve() it *is* at constant offset.
Moreover, for a kernel thread about to become a userland process the
same location is also fine - setting sp to that will leave the kernel
stack pointer at the very bottom of the kernel stack when we finally
switch to userland.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-09-16 12:06:34 -04:00
parent 533e6903be
commit d878d6dace
5 changed files with 9 additions and 37 deletions
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2
arch/m68k/include/asm/ptrace.h
View File

@ -85,6 +85,8 @@ struct switch_stack {
#define user_mode(regs) (!((regs)->sr & PS_S))
#define instruction_pointer(regs) ((regs)->pc)
#define profile_pc(regs) instruction_pointer(regs)
#define current_pt_regs() \
(struct pt_regs *)((char *)current_thread_info() + THREAD_SIZE) - 1
#define arch_has_single_step() (1)

2
arch/m68k/include/asm/unistd.h
View File

@ -382,6 +382,8 @@
#define __ARCH_WANT_SYS_SIGPROCMASK
#define __ARCH_WANT_SYS_RT_SIGACTION
#define __ARCH_WANT_SYS_RT_SIGSUSPEND
#define __ARCH_WANT_SYS_EXECVE
#define __ARCH_WANT_KERNEL_EXECVE
/*
* "Conditional" syscalls

5
arch/m68k/kernel/entry.S
View File

@ -122,6 +122,11 @@ ENTRY(ret_from_kernel_thread)
movel %d0,(%sp)
jra sys_exit
ENTRY(ret_from_kernel_execve)
movel 4(%sp), %sp
GET_CURRENT(%d0)
jra ret_from_exception
#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
#ifdef TRAP_DBG_INTERRUPT

20
arch/m68k/kernel/process.c
View File

@ -298,26 +298,6 @@ int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
EXPORT_SYMBOL(dump_fpu);
#endif /* CONFIG_FPU */
/*
* sys_execve() executes a new program.
*/
asmlinkage int sys_execve(const char __user *name,
const char __user *const __user *argv,
const char __user *const __user *envp)
{
int error;
char * filename;
struct pt_regs *regs = (struct pt_regs *) &name;
filename = getname(name);
error = PTR_ERR(filename);
if (IS_ERR(filename))
return error;
error = do_execve(filename, argv, envp, regs);
putname(filename);
return error;
}
unsigned long get_wchan(struct task_struct *p)
{
unsigned long fp, pc;

17
arch/m68k/kernel/sys_m68k.c
View File

@ -549,23 +549,6 @@ asmlinkage int sys_getpagesize(void)
return PAGE_SIZE;
}
/*
* Do a system call from kernel instead of calling sys_execve so we
* end up with proper pt_regs.
*/
int kernel_execve(const char *filename,
const char *const argv[],
const char *const envp[])
{
register long __res asm ("%d0") = __NR_execve;
register long __a asm ("%d1") = (long)(filename);
register long __b asm ("%d2") = (long)(argv);
register long __c asm ("%d3") = (long)(envp);
asm volatile ("trap #0" : "+d" (__res)
: "d" (__a), "d" (__b), "d" (__c));
return __res;
}
asmlinkage unsigned long sys_get_thread_area(void)
{
return current_thread_info()->tp_value;