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new helper: compat_user_stack_pointer() 

Compat counterpart of current_user_stack_pointer(); for most of the biarch
architectures those two are identical, but e.g. arm64 and arm use different
registers for stack pointer...

Note that amd64 variants of current_user_stack_pointer/compat_user_stack_pointer
do *not* rely on pt_regs having been through FIXUP_TOP_OF_STACK.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-12-14 13:49:35 -05:00
parent 5c49574ffd
commit 9b064fc3f9
3 changed files with 13 additions and 2 deletions
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5
arch/arm64/include/asm/compat.h
View File

@ -209,10 +209,11 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr)
return (u32)(unsigned long)uptr;
}
#define compat_user_stack_pointer() (current_pt_regs()->compat_sp)
static inline void __user *arch_compat_alloc_user_space(long len)
{
struct pt_regs *regs = task_pt_regs(current);
return (void __user *)regs->compat_sp - len;
return (void __user *)compat_user_stack_pointer() - len;
}
struct compat_ipc64_perm {

7
arch/x86/include/asm/ptrace.h
View File

@ -203,6 +203,13 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
#endif
}
#define current_user_stack_pointer() this_cpu_read(old_rsp)
/* ia32 vs. x32 difference */
#define compat_user_stack_pointer() \
(test_thread_flag(TIF_IA32) \
? current_pt_regs()->sp \
: this_cpu_read(old_rsp))
#endif
#ifdef CONFIG_X86_32

3
include/linux/compat.h
View File

@ -65,6 +65,9 @@
#endif /* CONFIG_HAVE_SYSCALL_WRAPPERS */
#ifndef compat_user_stack_pointer
#define compat_user_stack_pointer() current_user_stack_pointer()
#endif
#define compat_jiffies_to_clock_t(x) \
(((unsigned long)(x) * COMPAT_USER_HZ) / HZ)