[PATCH AUTOSEL 6.2 06/30] m68k: mm: Fix systems with memory at end of 32-bit address space

Sasha Levin
2023-03-20T00:53:46Z

From: Kars de Jong <jongk@linux-m68k.org>

[ Upstream commit 0d9fad91abfd723ea5070a46d98a9f4496c93ba9 ]

The calculation of end addresses of memory chunks overflowed to 0 when
a memory chunk is located at the end of 32-bit address space.
This is the case for the HP300 architecture.

Link: https://lore.kernel.org/linux-m68k/CACz-3rhUo5pgNwdWHaPWmz+30Qo9xCg70wNxdf7o5x-6tXq8QQ@mail.gmail.com/
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230223112349.26675-1-jongk@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/m68k/mm/motorola.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 2a375637e0077..9113012240789 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -437,7 +437,7 @@ void __init paging_init(void)
}

min_addr = m68k_memory[0].addr;
- max_addr = min_addr + m68k_memory[0].size;
+ max_addr = min_addr + m68k_memory[0].size - 1;
memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,
MEMBLOCK_NONE);
for (i = 1; i < m68k_num_memory;) {
@@ -452,21 +452,21 @@ void __init paging_init(void)
}
memblock_add_node(m68k_memory[i].addr, m68k_memory[i].size, i,
MEMBLOCK_NONE);
- addr = m68k_memory[i].addr + m68k_memory[i].size;
+ addr = m68k_memory[i].addr + m68k_memory[i].size - 1;
if (addr > max_addr)
max_addr = addr;
i++;
}
m68k_memoffset = min_addr - PAGE_OFFSET;
- m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;
+ m68k_virt_to_node_shift = fls(max_addr - min_addr) - 6;

module_fixup(NULL, __start_fixup, __stop_fixup);
flush_icache();

- high_memory = phys_to_virt(max_addr);
+ high_memory = phys_to_virt(max_addr) + 1;

min_low_pfn = availmem >> PAGE_SHIFT;
- max_pfn = max_low_pfn = max_addr >> PAGE_SHIFT;
+ max_pfn = max_low_pfn = (max_addr >> PAGE_SHIFT) + 1;

/* Reserve kernel text/data/bss and the memory allocated in head.S */
memblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);
--
2.39.2