[PATCH v7 12/23] arm64: Extract early FDT mapping from kaslr_early_init()

Marc Zyngier
2021-02-08T10:23:30Z

As we want to parse more options very early in the kernel lifetime,
let's always map the FDT early. This is achieved by moving that
code out of kaslr_early_init().

No functionnal change expected.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
---
arch/arm64/include/asm/setup.h | 11 +++++++++++
arch/arm64/kernel/head.S | 3 ++-
arch/arm64/kernel/kaslr.c | 7 +++----
arch/arm64/kernel/setup.c | 15 +++++++++++++++
4 files changed, 31 insertions(+), 5 deletions(-)
create mode 100644 arch/arm64/include/asm/setup.h

diff --git a/arch/arm64/include/asm/setup.h b/arch/arm64/include/asm/setup.h
new file mode 100644
index 000000000000..d3320618ed14
--- /dev/null
+++ b/arch/arm64/include/asm/setup.h
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef __ARM64_ASM_SETUP_H
+#define __ARM64_ASM_SETUP_H
+
+#include <uapi/asm/setup.h>
+
+void *get_early_fdt_ptr(void);
+void early_fdt_map(u64 dt_phys);
+
+#endif
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index b425d2587cdb..d74e5f84042e 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -433,6 +433,8 @@ SYM_FUNC_START_LOCAL(__primary_switched)
bl __pi_memset
dsb ishst // Make zero page visible to PTW

+ mov x0, x21 // pass FDT address in x0
+ bl early_fdt_map // Try mapping the FDT early
bl switch_to_vhe
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
bl kasan_early_init
@@ -440,7 +442,6 @@ SYM_FUNC_START_LOCAL(__primary_switched)
#ifdef CONFIG_RANDOMIZE_BASE
tst x23, ~(MIN_KIMG_ALIGN - 1) // already running randomized?
b.ne 0f
- mov x0, x21 // pass FDT address in x0
bl kaslr_early_init // parse FDT for KASLR options
cbz x0, 0f // KASLR disabled? just proceed
orr x23, x23, x0 // record KASLR offset
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 1c74c45b9494..5fc86e7d01a1 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -19,6 +19,7 @@
#include <asm/memory.h>
#include <asm/mmu.h>
#include <asm/sections.h>
+#include <asm/setup.h>

enum kaslr_status {
KASLR_ENABLED,
@@ -92,12 +93,11 @@ static __init bool is_kaslr_disabled_cmdline(void *fdt)
* containing function pointers) to be reinitialized, and zero-initialized
* .bss variables will be reset to 0.
*/
-u64 __init kaslr_early_init(u64 dt_phys)
+u64 __init kaslr_early_init(void)
{
void *fdt;
u64 seed, offset, mask, module_range;
unsigned long raw;
- int size;

/*
* Set a reasonable default for module_alloc_base in case
@@ -111,8 +111,7 @@ u64 __init kaslr_early_init(u64 dt_phys)
* and proceed with KASLR disabled. We will make another
* attempt at mapping the FDT in setup_machine()
*/
- early_fixmap_init();
- fdt = fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL);
+ fdt = get_early_fdt_ptr();
if (!fdt) {
kaslr_status = KASLR_DISABLED_FDT_REMAP;
return 0;
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index c18aacde8bb0..61845c0821d9 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -168,6 +168,21 @@ static void __init smp_build_mpidr_hash(void)
pr_warn("Large number of MPIDR hash buckets detected\n");
}

+static void *early_fdt_ptr __initdata;
+
+void __init *get_early_fdt_ptr(void)
+{
+ return early_fdt_ptr;
+}
+
+asmlinkage void __init early_fdt_map(u64 dt_phys)
+{
+ int fdt_size;
+
+ early_fixmap_init();
+ early_fdt_ptr = fixmap_remap_fdt(dt_phys, &fdt_size, PAGE_KERNEL);
+}
+
static void __init setup_machine_fdt(phys_addr_t dt_phys)
{
int size;
--
2.29.2