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

3 files changed, 6 insertions, 6 deletions

diff --git a/arch/powerpc/platforms/chrp/nvram.c b/arch/powerpc/platforms/chrp/nvram.c
index dab78076fedb..0eedae96498c 100644
--- a/arch/powerpc/platforms/chrp/nvram.c
+++ b/arch/powerpc/platforms/chrp/nvram.c
@@ -31,7 +31,7 @@ static unsigned char chrp_nvram_read_val(int addr)
 		return 0xff;
 	}
 	spin_lock_irqsave(&nvram_lock, flags);
-	if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
+	if ((rtas_call(rtas_function_token(RTAS_FN_NVRAM_FETCH), 3, 2, &done, addr,
 		       __pa(nvram_buf), 1) != 0) || 1 != done)
 		ret = 0xff;
 	else
@@ -53,7 +53,7 @@ static void chrp_nvram_write_val(int addr, unsigned char val)
 	}
 	spin_lock_irqsave(&nvram_lock, flags);
 	nvram_buf[0] = val;
-	if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
+	if ((rtas_call(rtas_function_token(RTAS_FN_NVRAM_STORE), 3, 2, &done, addr,
 		       __pa(nvram_buf), 1) != 0) || 1 != done)
 		printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
 	spin_unlock_irqrestore(&nvram_lock, flags);
diff --git a/arch/powerpc/platforms/chrp/pci.c b/arch/powerpc/platforms/chrp/pci.c
index 6f6598e771ff..428fd2a7b3ee 100644
--- a/arch/powerpc/platforms/chrp/pci.c
+++ b/arch/powerpc/platforms/chrp/pci.c
@@ -104,7 +104,7 @@ static int rtas_read_config(struct pci_bus *bus, unsigned int devfn, int offset,
         int ret = -1;
 	int rval;
 
-	rval = rtas_call(rtas_token("read-pci-config"), 2, 2, &ret, addr, len);
+	rval = rtas_call(rtas_function_token(RTAS_FN_READ_PCI_CONFIG), 2, 2, &ret, addr, len);
 	*val = ret;
 	return rval? PCIBIOS_DEVICE_NOT_FOUND: PCIBIOS_SUCCESSFUL;
 }
@@ -118,7 +118,7 @@ static int rtas_write_config(struct pci_bus *bus, unsigned int devfn, int offset
 		| (hose->global_number << 24);
 	int rval;
 
-	rval = rtas_call(rtas_token("write-pci-config"), 3, 1, NULL,
+	rval = rtas_call(rtas_function_token(RTAS_FN_WRITE_PCI_CONFIG), 3, 1, NULL,
 			 addr, len, val);
 	return rval? PCIBIOS_DEVICE_NOT_FOUND: PCIBIOS_SUCCESSFUL;
 }
diff --git a/arch/powerpc/platforms/chrp/setup.c b/arch/powerpc/platforms/chrp/setup.c
index ec63c0558db6..d9049ceb1046 100644
--- a/arch/powerpc/platforms/chrp/setup.c
+++ b/arch/powerpc/platforms/chrp/setup.c
@@ -323,11 +323,11 @@ static void __init chrp_setup_arch(void)
 	printk("chrp type = %x [%s]\n", _chrp_type, chrp_names[_chrp_type]);
 
 	rtas_initialize();
-	if (rtas_token("display-character") >= 0)
+	if (rtas_function_token(RTAS_FN_DISPLAY_CHARACTER) >= 0)
 		ppc_md.progress = rtas_progress;
 
 	/* use RTAS time-of-day routines if available */
-	if (rtas_token("get-time-of-day") != RTAS_UNKNOWN_SERVICE) {
+	if (rtas_function_token(RTAS_FN_GET_TIME_OF_DAY) != RTAS_UNKNOWN_SERVICE) {
 		ppc_md.get_boot_time	= rtas_get_boot_time;
 		ppc_md.get_rtc_time	= rtas_get_rtc_time;
 		ppc_md.set_rtc_time	= rtas_set_rtc_time;