arm64: unmap idmap earlier

During boot we leave the idmap in place until paging_init, as we
previously had to wait for the zero page to become allocated and
accessible.

Now that we have a statically-allocated zero page, we can uninstall the
idmap much earlier in the boot process, making it far easier to spot
accidental use of physical addresses. This also brings the cold boot
path in line with the secondary boot path.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 86ccce896cb0aa800a7a6dcd29b41ffc4eeb1a75)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index f6621ba071f9082f66a289c8d123948b4f44ed70..cfed56f0ad26d64714b137f124ac8112b12331b1 100644 (file)
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -314,6 +314,12 @@ void __init setup_arch(char **cmdline_p)
         */
        local_async_enable();
 
+       /*
+        * TTBR0 is only used for the identity mapping at this stage. Make it
+        * point to zero page to avoid speculatively fetching new entries.
+        */
+       cpu_uninstall_idmap();
+
        efi_init();
        arm64_memblock_init();
 

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 74898e5be57a2e1999cbe62fdef74d027bfb60cf..1e2ae807130f289919add92c7870917cddb20abb 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -453,12 +453,6 @@ void __init paging_init(void)
        fixup_executable();
 
        bootmem_init();
-
-       /*
-        * TTBR0 is only used for the identity mapping at this stage. Make it
-        * point to zero page to avoid speculatively fetching new entries.
-        */
-       cpu_uninstall_idmap();
 }
 
 /*