powerpc/rtas: arch-wide function token lookup conversions

With the tokens for all implemented RTAS functions now available via
rtas_function_token(), which is optimal and safe for arbitrary
contexts, there is no need to use rtas_token() or cache its result.

Most conversions are trivial, but a few are worth describing in more
detail:

* Error injection token comparisons for lockdown purposes are
  consolidated into a simple predicate: token_is_restricted_errinjct().

* A couple of special cases in block_rtas_call() do not use
  rtas_token() but perform string comparisons against names in the
  function table. These are converted to compare against token values
  instead, which is logically equivalent but less expensive.

* The lookup for the ibm,os-term token can be deferred until needed,
  instead of caching it at boot to avoid device tree traversal during
  panic.

* Since rtas_function_token() accesses a read-only data structure
  without taking any locks, xmon's lookup of set-indicator can be
  performed as needed instead of cached at startup.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230125-b4-powerpc-rtas-queue-v3-20-26929c8cce78@linux.ibm.com

1 files changed, 10 insertions, 11 deletions

diff --git a/arch/powerpc/kernel/rtas_flash.c b/arch/powerpc/kernel/rtas_flash.c
index bc817a5619d6..4caf5e3079eb 100644
--- a/arch/powerpc/kernel/rtas_flash.c
+++ b/arch/powerpc/kernel/rtas_flash.c
@@ -376,7 +376,7 @@ static void manage_flash(struct rtas_manage_flash_t *args_buf, unsigned int op)
 	s32 rc;
 
 	do {
-		rc = rtas_call(rtas_token("ibm,manage-flash-image"), 1, 1,
+		rc = rtas_call(rtas_function_token(RTAS_FN_IBM_MANAGE_FLASH_IMAGE), 1, 1,
 			       NULL, op);
 	} while (rtas_busy_delay(rc));
 
@@ -444,7 +444,7 @@ error:
  */
 static void validate_flash(struct rtas_validate_flash_t *args_buf)
 {
-	int token = rtas_token("ibm,validate-flash-image");
+	int token = rtas_function_token(RTAS_FN_IBM_VALIDATE_FLASH_IMAGE);
 	int update_results;
 	s32 rc;	
 
@@ -570,7 +570,7 @@ static void rtas_flash_firmware(int reboot_type)
 		return;
 	}
 
-	update_token = rtas_token("ibm,update-flash-64-and-reboot");
+	update_token = rtas_function_token(RTAS_FN_IBM_UPDATE_FLASH_64_AND_REBOOT);
 	if (update_token == RTAS_UNKNOWN_SERVICE) {
 		printk(KERN_ALERT "FLASH: ibm,update-flash-64-and-reboot "
 		       "is not available -- not a service partition?\n");
@@ -653,7 +653,7 @@ static void rtas_flash_firmware(int reboot_type)
  */
 struct rtas_flash_file {
 	const char *filename;
-	const char *rtas_call_name;
+	const rtas_fn_handle_t handle;
 	int *status;
 	const struct proc_ops ops;
 };
@@ -661,7 +661,7 @@ struct rtas_flash_file {
 static const struct rtas_flash_file rtas_flash_files[] = {
 	{
 		.filename	= "powerpc/rtas/" FIRMWARE_FLASH_NAME,
-		.rtas_call_name	= "ibm,update-flash-64-and-reboot",
+		.handle		= RTAS_FN_IBM_UPDATE_FLASH_64_AND_REBOOT,
 		.status		= &rtas_update_flash_data.status,
 		.ops.proc_read	= rtas_flash_read_msg,
 		.ops.proc_write	= rtas_flash_write,
@@ -670,7 +670,7 @@ static const struct rtas_flash_file rtas_flash_files[] = {
 	},
 	{
 		.filename	= "powerpc/rtas/" FIRMWARE_UPDATE_NAME,
-		.rtas_call_name	= "ibm,update-flash-64-and-reboot",
+		.handle		= RTAS_FN_IBM_UPDATE_FLASH_64_AND_REBOOT,
 		.status		= &rtas_update_flash_data.status,
 		.ops.proc_read	= rtas_flash_read_num,
 		.ops.proc_write	= rtas_flash_write,
@@ -679,7 +679,7 @@ static const struct rtas_flash_file rtas_flash_files[] = {
 	},
 	{
 		.filename	= "powerpc/rtas/" VALIDATE_FLASH_NAME,
-		.rtas_call_name	= "ibm,validate-flash-image",
+		.handle		= RTAS_FN_IBM_VALIDATE_FLASH_IMAGE,
 		.status		= &rtas_validate_flash_data.status,
 		.ops.proc_read	= validate_flash_read,
 		.ops.proc_write	= validate_flash_write,
@@ -688,7 +688,7 @@ static const struct rtas_flash_file rtas_flash_files[] = {
 	},
 	{
 		.filename	= "powerpc/rtas/" MANAGE_FLASH_NAME,
-		.rtas_call_name	= "ibm,manage-flash-image",
+		.handle		= RTAS_FN_IBM_MANAGE_FLASH_IMAGE,
 		.status		= &rtas_manage_flash_data.status,
 		.ops.proc_read	= manage_flash_read,
 		.ops.proc_write	= manage_flash_write,
@@ -700,8 +700,7 @@ static int __init rtas_flash_init(void)
 {
 	int i;
 
-	if (rtas_token("ibm,update-flash-64-and-reboot") ==
-		       RTAS_UNKNOWN_SERVICE) {
+	if (rtas_function_token(RTAS_FN_IBM_UPDATE_FLASH_64_AND_REBOOT) == RTAS_UNKNOWN_SERVICE) {
 		pr_info("rtas_flash: no firmware flash support\n");
 		return -EINVAL;
 	}
@@ -730,7 +729,7 @@ static int __init rtas_flash_init(void)
 		 * This code assumes that the status int is the first member of the
 		 * struct
 		 */
-		token = rtas_token(f->rtas_call_name);
+		token = rtas_function_token(f->handle);
 		if (token == RTAS_UNKNOWN_SERVICE)
 			*f->status = FLASH_AUTH;
 		else