[RFC PATCH 08/20] arm64: unmap idmap earlier

[Mark Rutland]

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 eaier 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 at arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Jeremy Linton <jeremy.linton at arm.com>
Cc: Laura Abbott <labbott at fedoraproject.org>
Cc: Will Deacon <will.deacon at arm.com>
---
 arch/arm64/kernel/setup.c | 6 ++++++
 arch/arm64/mm/mmu.c       | 6 ------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index f6621ba..cfed56f 100644
--- 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 98a98ac..0c16c25 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -445,12 +445,6 @@ 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();
 }
 
 /*
-- 
1.9.1