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MIPS: Detect bad _PFN_SHIFT values

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2 recent commits have fixed issues where _PFN_SHIFT grew too large due
to the introduction of too many pgprot bits in our PTEs for some MIPS32
kernel configurations. Tracking down such issues can be tricky, so add a
BUILD_BUG_ON() to help.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
This commit is contained in:
Paul Burton 2019-09-18 22:03:30 +00:00
parent d1af2ab36d
commit 05d013a036
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1 changed files with 6 additions and 0 deletions
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6
arch/mips/mm/init.c
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@ -446,6 +446,12 @@ static inline void __init mem_init_free_highmem(void)
void __init mem_init(void)
{
/*
* When _PFN_SHIFT is greater than PAGE_SHIFT we won't have enough PTE
* bits to hold a full 32b physical address on MIPS32 systems.
*/
BUILD_BUG_ON(IS_ENABLED(CONFIG_32BIT) && (_PFN_SHIFT > PAGE_SHIFT));
#ifdef CONFIG_HIGHMEM
#ifdef CONFIG_DISCONTIGMEM
#error "CONFIG_HIGHMEM and CONFIG_DISCONTIGMEM dont work together yet"