powerpc/perf: consolidate valid_user_sp -> invalid_user_sp

Merge the 32bit and 64bit version.

Halve the check constants on 32bit.

Use STACK_TOP since it is defined.

Passing is_64 is now redundant since is_32bit_task() is used to
determine which callchain variant should be used. Use STACK_TOP and
is_32bit_task() directly.

This removes a page from the valid 32bit area on 64bit:
 #define TASK_SIZE_USER32 (0x0000000100000000UL - (1 * PAGE_SIZE))
 #define STACK_TOP_USER32 TASK_SIZE_USER32

Change return value to bool. It is inverted by users anyway.

Change to invalid_user_sp to avoid inverting the return value twice.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/be8e40fc0737fb28ad08b198552dee7cac1c5ce2.1584699455.git.msuchanek@suse.de

arch/powerpc/perf/callchain.c

@@ -102,6 +102,14 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 	}
 }
 
+static inline bool invalid_user_sp(unsigned long sp)
+{
+	unsigned long mask = is_32bit_task() ? 3 : 7;
+	unsigned long top = STACK_TOP - (is_32bit_task() ? 16 : 32);
+
+	return (!sp || (sp & mask) || (sp > top));
+}
+
 #ifdef CONFIG_PPC64
 /*
  * On 64-bit we don't want to invoke hash_page on user addresses from
@@ -161,13 +169,6 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
 	return read_user_stack_slow(ptr, ret, 8);
 }
 
-static inline int valid_user_sp(unsigned long sp, int is_64)
-{
-	if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
-		return 0;
-	return 1;
-}
-
 /*
  * 64-bit user processes use the same stack frame for RT and non-RT signals.
  */
@@ -226,7 +227,7 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
 
 	while (entry->nr < entry->max_stack) {
 		fp = (unsigned long __user *) sp;
-		if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
+		if (invalid_user_sp(sp) || read_user_stack_64(fp, &next_sp))
 			return;
 		if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
 			return;
@@ -275,13 +276,6 @@ static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry
 {
 }
 
-static inline int valid_user_sp(unsigned long sp, int is_64)
-{
-	if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
-		return 0;
-	return 1;
-}
-
 #define __SIGNAL_FRAMESIZE32	__SIGNAL_FRAMESIZE
 #define sigcontext32		sigcontext
 #define mcontext32		mcontext
@@ -423,7 +417,7 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
 
 	while (entry->nr < entry->max_stack) {
 		fp = (unsigned int __user *) (unsigned long) sp;
-		if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
+		if (invalid_user_sp(sp) || read_user_stack_32(fp, &next_sp))
 			return;
 		if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
 			return;