linux-kernel - [PATCH AUTOSEL 6.1 9/9] powerpc/powermac: Use early_* IO variants in via_calibrate

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Message-Id: <20230822113130.3550050-9-sashal@kernel.org>
Date:   Tue, 22 Aug 2023 07:31:30 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Benjamin Gray <bgray@...ux.ibm.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH AUTOSEL 6.1 9/9] powerpc/powermac: Use early_* IO variants in via_calibrate_decr()

From: Benjamin Gray <bgray@...ux.ibm.com>

[ Upstream commit 86582e6189dd8f9f52c25d46c70fe5d111da6345 ]

On a powermac platform, via the call path:

  start_kernel()
    time_init()
      ppc_md.calibrate_decr() (pmac_calibrate_decr)
        via_calibrate_decr()

ioremap() and iounmap() are called. The unmap can enable interrupts
unexpectedly (cond_resched() in vunmap_pmd_range()), which causes a
warning later in the boot sequence in start_kernel().

Use the early_* variants of these IO functions to prevent this.

The issue is pre-existing, but is surfaced by commit 721255b9826b
("genirq: Use a maple tree for interrupt descriptor management").

Signed-off-by: Benjamin Gray <bgray@...ux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://msgid.link/20230706010816.72682-1-bgray@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/platforms/powermac/time.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powermac/time.c b/arch/powerpc/platforms/powermac/time.c
index 4c5790aff1b54..8633891b7aa58 100644
--- a/arch/powerpc/platforms/powermac/time.c
+++ b/arch/powerpc/platforms/powermac/time.c
@@ -26,8 +26,8 @@
 #include <linux/rtc.h>
 #include <linux/of_address.h>
 
+#include <asm/early_ioremap.h>
 #include <asm/sections.h>
-#include <asm/io.h>
 #include <asm/machdep.h>
 #include <asm/time.h>
 #include <asm/nvram.h>
@@ -182,7 +182,7 @@ static int __init via_calibrate_decr(void)
 		return 0;
 	}
 	of_node_put(vias);
-	via = ioremap(rsrc.start, resource_size(&rsrc));
+	via = early_ioremap(rsrc.start, resource_size(&rsrc));
 	if (via == NULL) {
 		printk(KERN_ERR "Failed to map VIA for timer calibration !\n");
 		return 0;
@@ -207,7 +207,7 @@ static int __init via_calibrate_decr(void)
 
 	ppc_tb_freq = (dstart - dend) * 100 / 6;
 
-	iounmap(via);
+	early_iounmap((void *)via, resource_size(&rsrc));
 
 	return 1;
 }
-- 
2.40.1