x86/percpu: Clean up percpu_stable_op()

Use __pcpu_size_call_return() to simplify this_cpu_read_stable().
Also remove __bad_percpu_size() which is now unused.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dennis Zhou <dennis@kernel.org>
Link: https://lkml.kernel.org/r/20200720204925.3654302-10-ndesaulniers@google.com

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 7efc0b5..cf2b9c2 100644 (file)
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -85,7 +85,6 @@
 
 /* For arch-specific code, we can use direct single-insn ops (they
  * don't give an lvalue though). */
-extern void __bad_percpu_size(void);
 
 #define __pcpu_type_1 u8
 #define __pcpu_type_2 u16
@@ -167,33 +166,13 @@ do {                                                                      \
        (typeof(_var))(unsigned long) pfo_val__;                        \
 })
 
-#define percpu_stable_op(op, var)                      \
-({                                                     \
-       typeof(var) pfo_ret__;                          \
-       switch (sizeof(var)) {                          \
-       case 1:                                         \
-               asm(op "b "__percpu_arg(P1)",%0"        \
-                   : "=q" (pfo_ret__)                  \
-                   : "p" (&(var)));                    \
-               break;                                  \
-       case 2:                                         \
-               asm(op "w "__percpu_arg(P1)",%0"        \
-                   : "=r" (pfo_ret__)                  \
-                   : "p" (&(var)));                    \
-               break;                                  \
-       case 4:                                         \
-               asm(op "l "__percpu_arg(P1)",%0"        \
-                   : "=r" (pfo_ret__)                  \
-                   : "p" (&(var)));                    \
-               break;                                  \
-       case 8:                                         \
-               asm(op "q "__percpu_arg(P1)",%0"        \
-                   : "=r" (pfo_ret__)                  \
-                   : "p" (&(var)));                    \
-               break;                                  \
-       default: __bad_percpu_size();                   \
-       }                                               \
-       pfo_ret__;                                      \
+#define percpu_stable_op(size, op, _var)                               \
+({                                                                     \
+       __pcpu_type_##size pfo_val__;                                   \
+       asm(__pcpu_op2_##size(op, __percpu_arg(P[var]), "%[val]")       \
+           : [val] __pcpu_reg_##size("=", pfo_val__)                   \
+           : [var] "p" (&(_var)));                                     \
+       (typeof(_var))(unsigned long) pfo_val__;                        \
 })
 
 /*
@@ -258,7 +237,11 @@ do {                                                                       \
  * per-thread variables implemented as per-cpu variables and thus
  * stable for the duration of the respective task.
  */
-#define this_cpu_read_stable(var)      percpu_stable_op("mov", var)
+#define this_cpu_read_stable_1(pcp)    percpu_stable_op(1, "mov", pcp)
+#define this_cpu_read_stable_2(pcp)    percpu_stable_op(2, "mov", pcp)
+#define this_cpu_read_stable_4(pcp)    percpu_stable_op(4, "mov", pcp)
+#define this_cpu_read_stable_8(pcp)    percpu_stable_op(8, "mov", pcp)
+#define this_cpu_read_stable(pcp)      __pcpu_size_call_return(this_cpu_read_stable_, pcp)
 
 #define raw_cpu_read_1(pcp)            percpu_from_op(1, , "mov", pcp)
 #define raw_cpu_read_2(pcp)            percpu_from_op(2, , "mov", pcp)