[PATCH] arm64: mm: Use __pa_symbol() for set_swapper_pgd()

[PATCH] arm64: mm: Use __pa_symbol() for set_swapper_pgd()

[James Morse]

commit 2330b7ca78350efcb ("arm64/mm: use fixmap to modify
swapper_pg_dir") modifies the swapper_pg_dir via the fixmap
as the kernel page tables have been moved to a read-only
part of the kernel mapping.

Using __pa() to setup the fixmap causes CONFIG_DEBUG_VIRTUAL
to fire, as this function is used on the kernel-image swapper
address. The in_swapper_pgdir() test before each call of this
function means set_swapper_pgd() will only ever be called when
pgdp points somewhere in the kernel-image mapping of
swapper_pd_dir. Use __pa_symbol().

Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: James Morse <james.morse@arm.com>
CC: Jun Yao <yaojun8558363@gmail.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 arch/arm64/mm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6f0e2edcc114..6deb836a102a 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -74,7 +74,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
 	pgd_t *fixmap_pgdp;
 
 	spin_lock(&swapper_pgdir_lock);
-	fixmap_pgdp = pgd_set_fixmap(__pa(pgdp));
+	fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp));
 	WRITE_ONCE(*fixmap_pgdp, pgd);
 	/*
 	 * We need dsb(ishst) here to ensure the page-table-walker sees
-- 
2.19.0

[PATCH] arm64: mm: Use __pa_symbol() for set_swapper_pgd()

[Will Deacon]

On Wed, Oct 10, 2018 at 03:43:22PM +0100, James Morse wrote:
> commit 2330b7ca78350efcb ("arm64/mm: use fixmap to modify
> swapper_pg_dir") modifies the swapper_pg_dir via the fixmap
> as the kernel page tables have been moved to a read-only
> part of the kernel mapping.
> 
> Using __pa() to setup the fixmap causes CONFIG_DEBUG_VIRTUAL
> to fire, as this function is used on the kernel-image swapper
> address. The in_swapper_pgdir() test before each call of this
> function means set_swapper_pgd() will only ever be called when
> pgdp points somewhere in the kernel-image mapping of
> swapper_pd_dir. Use __pa_symbol().
> 
> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: James Morse <james.morse@arm.com>
> CC: Jun Yao <yaojun8558363@gmail.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
>  arch/arm64/mm/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Since this only affects for-next/core, Catalin should pick this up for 4.20.

Acked-by: Will Deacon <will.deacon@arm.com>

Will

[PATCH] arm64: mm: Use __pa_symbol() for set_swapper_pgd()

[Catalin Marinas]

On Wed, Oct 10, 2018 at 03:43:22PM +0100, James Morse wrote:
> commit 2330b7ca78350efcb ("arm64/mm: use fixmap to modify
> swapper_pg_dir") modifies the swapper_pg_dir via the fixmap
> as the kernel page tables have been moved to a read-only
> part of the kernel mapping.
> 
> Using __pa() to setup the fixmap causes CONFIG_DEBUG_VIRTUAL
> to fire, as this function is used on the kernel-image swapper
> address. The in_swapper_pgdir() test before each call of this
> function means set_swapper_pgd() will only ever be called when
> pgdp points somewhere in the kernel-image mapping of
> swapper_pd_dir. Use __pa_symbol().
> 
> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: James Morse <james.morse@arm.com>
> CC: Jun Yao <yaojun8558363@gmail.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Applied. Thanks.

-- 
Catalin