Convert the function macros user_mode(), instruction_pointer(), and
user_stack_pointer() to inline functions, to align their definition
with x86 and arm64.

Use const qualifier on struct pt_regs pointer parameters to prevent
compiler warnings:

arch/s390/kernel/stacktrace.c: In function ‘arch_stack_walk_user_common’:
arch/s390/kernel/stacktrace.c:114:34: warning: passing argument 1 of
‘instruction_pointer’ discards ‘const’ qualifier from pointer target
type [-Wdiscarded-qualifiers]
...
arch/s390/kernel/stacktrace.c:117:48: warning: passing argument 1 of
‘user_stack_pointer’ discards ‘const’ qualifier from pointer target
type [-Wdiscarded-qualifiers]
...

While at it add const qualifier to all struct pt_regs pointer parameters
that are accessed read-only and use __always_inline instead of inline to
harmonize the helper functions.

[hca@linux.ibm.com: Use psw_bits() helper]

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---

Notes (jremus):
    Changes in v4:
    - New patch.  Split out "while at it" changes from patch "s390/ptrace:
      Provide frame_pointer()" to go upstream separately. (Heiko)

 arch/s390/include/asm/ptrace.h | 37 ++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 962cf042c66d..e6ec0ccf3d73 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -214,16 +214,23 @@ void update_cr_regs(struct task_struct *task);
 #define arch_has_single_step()	(1)
 #define arch_has_block_step()	(1)
 
-#define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
-#define instruction_pointer(regs) ((regs)->psw.addr)
-#define user_stack_pointer(regs)((regs)->gprs[15])
 #define profile_pc(regs) instruction_pointer(regs)
 
-static inline long regs_return_value(struct pt_regs *regs)
+static __always_inline bool user_mode(const struct pt_regs *regs)
+{
+	return psw_bits(regs->psw).pstate;
+}
+
+static inline long regs_return_value(const struct pt_regs *regs)
 {
 	return regs->gprs[2];
 }
 
+static __always_inline unsigned long instruction_pointer(const struct pt_regs *regs)
+{
+	return regs->psw.addr;
+}
+
 static inline void instruction_pointer_set(struct pt_regs *regs,
 					   unsigned long val)
 {
@@ -233,19 +240,26 @@ static inline void instruction_pointer_set(struct pt_regs *regs,
 int regs_query_register_offset(const char *name);
 const char *regs_query_register_name(unsigned int offset);
 
-static __always_inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+static __always_inline unsigned long kernel_stack_pointer(const struct pt_regs *regs)
+{
+	return regs->gprs[15];
+}
+
+static __always_inline unsigned long user_stack_pointer(const struct pt_regs *regs)
 {
 	return regs->gprs[15];
 }
 
-static __always_inline unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
+static __always_inline unsigned long regs_get_register(const struct pt_regs *regs,
+						       unsigned int offset)
 {
 	if (offset >= NUM_GPRS)
 		return 0;
 	return regs->gprs[offset];
 }
 
-static __always_inline int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
+static __always_inline int regs_within_kernel_stack(const struct pt_regs *regs,
+						    unsigned long addr)
 {
 	unsigned long ksp = kernel_stack_pointer(regs);
 
@@ -261,7 +275,8 @@ static __always_inline int regs_within_kernel_stack(struct pt_regs *regs, unsign
  * is specifined by @regs. If the @n th entry is NOT in the kernel stack,
  * this returns 0.
  */
-static __always_inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
+static __always_inline unsigned long regs_get_kernel_stack_nth(const struct pt_regs *regs,
+							       unsigned int n)
 {
 	unsigned long addr;
 
@@ -278,8 +293,8 @@ static __always_inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *r
  *
  * regs_get_kernel_argument() returns @n th argument of the function call.
  */
-static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
-						     unsigned int n)
+static __always_inline unsigned long regs_get_kernel_argument(const struct pt_regs *regs,
+							      unsigned int n)
 {
 	unsigned int argoffset = STACK_FRAME_OVERHEAD / sizeof(long);
 
@@ -290,7 +305,7 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 	return regs_get_kernel_stack_nth(regs, argoffset + n);
 }
 
-static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
+static __always_inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 {
 	regs->gprs[2] = rc;
 }
-- 
2.51.0