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>

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>
Al Viro
1 parent 5c49574ffd
Showing 3 changed files with 13 additions and 2 deletions Side-by-side Diff
arch/arm64/include/asm/compat.h
arch/x86/include/asm/ptrace.h
include/linux/compat.h
@@ -209,10 +209,11 @@
 	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 {
@@ -203,6 +203,13 @@
 	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
@@ -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)
...	...	@@ -209,10 +209,11 @@
209	209	return (u32)(unsigned long)uptr;
210	210	}
211	211
	212	+#define compat_user_stack_pointer() (current_pt_regs()->compat_sp)
	213	+
212	214	static inline void __user *arch_compat_alloc_user_space(long len)
213	215	{
214		- struct pt_regs *regs = task_pt_regs(current);
215		- return (void __user *)regs->compat_sp - len;
	216	+ return (void __user *)compat_user_stack_pointer() - len;
216	217	}
217	218
218	219	struct compat_ipc64_perm {
...	...	@@ -203,6 +203,13 @@
203	203	return regs->cs == __USER_CS \|\| regs->cs == pv_info.extra_user_64bit_cs;
204	204	#endif
205	205	}
	206	+
	207	+#define current_user_stack_pointer() this_cpu_read(old_rsp)
	208	+/* ia32 vs. x32 difference */
	209	+#define compat_user_stack_pointer() \
	210	+ (test_thread_flag(TIF_IA32) \
	211	+ ? current_pt_regs()->sp \
	212	+ : this_cpu_read(old_rsp))
206	213	#endif
207	214
208	215	#ifdef CONFIG_X86_32
...	...	@@ -65,6 +65,9 @@
65	65
66	66	#endif /* CONFIG_HAVE_SYSCALL_WRAPPERS */
67	67
	68	+#ifndef compat_user_stack_pointer
	69	+#define compat_user_stack_pointer() current_user_stack_pointer()
	70	+#endif
68	71	#define compat_jiffies_to_clock_t(x) \
69	72	(((unsigned long)(x) * COMPAT_USER_HZ) / HZ)
70	73