powerpc/rtas: rename RTAS_RMOBUF_MAX to RTAS_USER_REGION_SIZE

RTAS_RMOBUF_MAX doesn't actually describe a "maximum" value in any
sense. It represents the size of an area of memory set aside for user
space to use as work areas for certain RTAS calls.

Rename it to RTAS_USER_REGION_SIZE.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210408140630.205502-6-nathanl@linux.ibm.com

arch/powerpc/include/asm/rtas.h

@@ -19,8 +19,8 @@
 #define RTAS_UNKNOWN_SERVICE (-1)
 #define RTAS_INSTANTIATE_MAX (1ULL<<30) /* Don't instantiate rtas at/above this value */
 
-/* Buffer size for ppc_rtas system call. */
-#define RTAS_RMOBUF_MAX (64 * 1024)
+/* Memory set aside for sys_rtas to use with calls that need a work area. */
+#define RTAS_USER_REGION_SIZE (64 * 1024)
 
 /* RTAS return status codes */
 #define RTAS_BUSY		-2    /* RTAS Busy */
@@ -357,7 +357,7 @@ extern void rtas_take_timebase(void);
 static inline int page_is_rtas_user_buf(unsigned long pfn)
 {
 	unsigned long paddr = (pfn << PAGE_SHIFT);
-	if (paddr >= rtas_rmo_buf && paddr < (rtas_rmo_buf + RTAS_RMOBUF_MAX))
+	if (paddr >= rtas_rmo_buf && paddr < (rtas_rmo_buf + RTAS_USER_REGION_SIZE))
 		return 1;
 	return 0;
 }

arch/powerpc/kernel/rtas-proc.c

@@ -767,6 +767,6 @@ static int ppc_rtas_tone_volume_show(struct seq_file *m, void *v)
  */
 static int ppc_rtas_rmo_buf_show(struct seq_file *m, void *v)
 {
-	seq_printf(m, "%016lx %x\n", rtas_rmo_buf, RTAS_RMOBUF_MAX);
+	seq_printf(m, "%016lx %x\n", rtas_rmo_buf, RTAS_USER_REGION_SIZE);
 	return 0;
 }

arch/powerpc/kernel/rtas.c

@@ -987,10 +987,10 @@ static struct rtas_filter rtas_filters[] __ro_after_init = {
 static bool in_rmo_buf(u32 base, u32 end)
 {
 	return base >= rtas_rmo_buf &&
-		base < (rtas_rmo_buf + RTAS_RMOBUF_MAX) &&
+		base < (rtas_rmo_buf + RTAS_USER_REGION_SIZE) &&
 		base <= end &&
 		end >= rtas_rmo_buf &&
-		end < (rtas_rmo_buf + RTAS_RMOBUF_MAX);
+		end < (rtas_rmo_buf + RTAS_USER_REGION_SIZE);
 }
 
 static bool block_rtas_call(int token, int nargs,
@@ -1202,7 +1202,7 @@ void __init rtas_initialize(void)
 	if (firmware_has_feature(FW_FEATURE_LPAR))
 		rtas_region = min(ppc64_rma_size, RTAS_INSTANTIATE_MAX);
 #endif
-	rtas_rmo_buf = memblock_phys_alloc_range(RTAS_RMOBUF_MAX, PAGE_SIZE,
+	rtas_rmo_buf = memblock_phys_alloc_range(RTAS_USER_REGION_SIZE, PAGE_SIZE,
 						 0, rtas_region);
 	if (!rtas_rmo_buf)
 		panic("ERROR: RTAS: Failed to allocate %lx bytes below %pa\n",