linux-kernel - [PATCH] powerpc/mm: fix early initialization failure for MMUs with no hash table

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Message-Id: <20211127020448.4008507-1-vladimir.oltean@nxp.com>
Date:   Sat, 27 Nov 2021 04:04:48 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] powerpc/mm: fix early initialization failure for MMUs with no hash table

The blamed patch attempted to do a trivial conversion of
map_mem_in_cams() by adding an extra "bool init" argument, but by
mistake, changed the way in which two call sites pass the other boolean
argument, "bool dry_run".

As a result, early_init_this_mmu() now calls map_mem_in_cams() with
dry_run=true, and setup_initial_memory_limit() calls with dry_run=false,
both of which are unintended changes.

This makes the kernel boot process hang here:

[    0.045211] e500 family performance monitor hardware support registered
[    0.051891] rcu: Hierarchical SRCU implementation.
[    0.057791] smp: Bringing up secondary CPUs ...

Issue noticed on a Freescale T1040.

Fixes: 52bda69ae8b5 ("powerpc/fsl_booke: Tell map_mem_in_cams() if init is done")
Cc: stable@...r.kernel.org
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 arch/powerpc/mm/nohash/tlb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/nohash/tlb.c b/arch/powerpc/mm/nohash/tlb.c
index 89353d4f5604..647bf454a0fa 100644
--- a/arch/powerpc/mm/nohash/tlb.c
+++ b/arch/powerpc/mm/nohash/tlb.c
@@ -645,7 +645,7 @@ static void early_init_this_mmu(void)
 
 		if (map)
 			linear_map_top = map_mem_in_cams(linear_map_top,
-							 num_cams, true, true);
+							 num_cams, false, true);
 	}
 #endif
 
@@ -766,7 +766,7 @@ void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 		num_cams = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) / 4;
 
 		linear_sz = map_mem_in_cams(first_memblock_size, num_cams,
-					    false, true);
+					    true, true);
 
 		ppc64_rma_size = min_t(u64, linear_sz, 0x40000000);
 	} else
-- 
2.25.1