riscv: errata: andes: Probe for IOCP only once in boot stage

We need to probe for IOCP only once during boot stage, as we were probing
for IOCP for all the stages this caused the below issue during module-init
stage,

[9.019104] Unable to handle kernel paging request at virtual address ffffffff8100d3a0
[9.027153] Oops [#1]
[9.029421] Modules linked in: rcar_canfd renesas_usbhs i2c_riic can_dev spi_rspi i2c_core
[9.037686] CPU: 0 PID: 90 Comm: udevd Not tainted 6.7.0-rc1+ #57
[9.043756] Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT)
[9.050339] epc : riscv_noncoherent_supported+0x10/0x3e
[9.055558]  ra : andes_errata_patch_func+0x4a/0x52
[9.060418] epc : ffffffff8000d8c2 ra : ffffffff8000d95c sp : ffffffc8003abb00
[9.067607]  gp : ffffffff814e25a0 tp : ffffffd80361e540 t0 : 0000000000000000
[9.074795]  t1 : 000000000900031e t2 : 0000000000000001 s0 : ffffffc8003abb20
[9.081984]  s1 : ffffffff015b57c7 a0 : 0000000000000000 a1 : 0000000000000001
[9.089172]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : ffffffff8100d8be
[9.096360]  a5 : 0000000000000001 a6 : 0000000000000001 a7 : 000000000900031e
[9.103548]  s2 : ffffffff015b57d7 s3 : 0000000000000001 s4 : 000000000000031e
[9.110736]  s5 : 8000000000008a45 s6 : 0000000000000500 s7 : 000000000000003f
[9.117924]  s8 : ffffffc8003abd48 s9 : ffffffff015b1140 s10: ffffffff8151a1b0
[9.125113]  s11: ffffffff015b1000 t3 : 0000000000000001 t4 : fefefefefefefeff
[9.132301]  t5 : ffffffff015b57c7 t6 : ffffffd8b63a6000
[9.137587] status: 0000000200000120 badaddr: ffffffff8100d3a0 cause: 000000000000000f
[9.145468] [<ffffffff8000d8c2>] riscv_noncoherent_supported+0x10/0x3e
[9.151972] [<ffffffff800027e8>] _apply_alternatives+0x84/0x86
[9.157784] [<ffffffff800029be>] apply_module_alternatives+0x10/0x1a
[9.164113] [<ffffffff80008fcc>] module_finalize+0x5e/0x7a
[9.169583] [<ffffffff80085cd6>] load_module+0xfd8/0x179c
[9.174965] [<ffffffff80086630>] init_module_from_file+0x76/0xaa
[9.180948] [<ffffffff800867f6>] __riscv_sys_finit_module+0x176/0x2a8
[9.187365] [<ffffffff80889862>] do_trap_ecall_u+0xbe/0x130
[9.192922] [<ffffffff808920bc>] ret_from_exception+0x0/0x64
[9.198573] Code: 0009 b7e9 6797 014d a783 85a7 c799 4785 0717 0100 (0123) aef7
[9.205994] ---[ end trace 0000000000000000 ]---

This is because we called riscv_noncoherent_supported() for all the stages
during IOCP probe. riscv_noncoherent_supported() function sets
noncoherent_supported variable to true which has an annotation set to
"__ro_after_init" due to which we were seeing the above splat. Fix this by
probing for IOCP only once in boot stage by having a boolean variable
"done" which will be set to true upon IOCP probe in errata_probe_iocp()
and we bail out early if "done" is set to true.

While at it make return type of errata_probe_iocp() to void as we were
not checking the return value in andes_errata_patch_func().

Fixes: e021ae7 ("riscv: errata: Add Andes alternative ports")
Signed-off-by: Lad Prabhakar <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Reviewed-by: Yu Chien Peter Lin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: prabhakarlad

arch/riscv/errata/andes/errata.c

@@ -38,29 +38,35 @@ static long ax45mp_iocp_sw_workaround(void)
 	return ret.error ? 0 : ret.value;
 }
 
-static bool errata_probe_iocp(unsigned int stage, unsigned long arch_id, unsigned long impid)
+static void errata_probe_iocp(unsigned int stage, unsigned long arch_id, unsigned long impid)
 {
+	static bool done;
+
 	if (!IS_ENABLED(CONFIG_ERRATA_ANDES_CMO))
-		return false;
+		return;
+
+	if (done)
+		return;
+
+	done = true;
 
 	if (arch_id != ANDESTECH_AX45MP_MARCHID || impid != ANDESTECH_AX45MP_MIMPID)
-		return false;
+		return;
 
 	if (!ax45mp_iocp_sw_workaround())
-		return false;
+		return;
 
 	/* Set this just to make core cbo code happy */
 	riscv_cbom_block_size = 1;
 	riscv_noncoherent_supported();
-
-	return true;
 }
 
 void __init_or_module andes_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
 					      unsigned long archid, unsigned long impid,
 					      unsigned int stage)
 {
-	errata_probe_iocp(stage, archid, impid);
+	if (stage == RISCV_ALTERNATIVES_BOOT)
+		errata_probe_iocp(stage, archid, impid);
 
 	/* we have nothing to patch here ATM so just return back */
 }