Subject: [PATCH 1/2] ARM: centralize phys-to-virt conversion of DT/ATAGS address

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 6 Oct 2020 11:49:17 +0200

Before moving the DT mapping out of the linear region, let's prepare
for this change by removing all the phys-to-virt translations of the
__atags_pointer variable, and perform this translation only once at
setup time.

Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 arch/arm/include/asm/prom.h   |  4 ++--
 arch/arm/kernel/atags.h       |  4 ++--
 arch/arm/kernel/atags_parse.c |  6 +++---
 arch/arm/kernel/devtree.c     |  6 +++---
 arch/arm/kernel/setup.c       | 14 +++++++++-----
 arch/arm/mm/mmu.c             |  4 ++--
 6 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
index 1e36c40533c1..402e3f34c7ed 100644
--- a/arch/arm/include/asm/prom.h
+++ b/arch/arm/include/asm/prom.h
@@ -9,12 +9,12 @@
 
 #ifdef CONFIG_OF
 
-extern const struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
+extern const struct machine_desc *setup_machine_fdt(void *dt_virt);
 extern void __init arm_dt_init_cpu_maps(void);
 
 #else /* CONFIG_OF */
 
-static inline const struct machine_desc *setup_machine_fdt(unsigned int dt_phys)
+static inline const struct machine_desc *setup_machine_fdt(void *dt_virt)
 {
 	return NULL;
 }
diff --git a/arch/arm/kernel/atags.h b/arch/arm/kernel/atags.h
index 067e12edc341..f2819c25b602 100644
--- a/arch/arm/kernel/atags.h
+++ b/arch/arm/kernel/atags.h
@@ -2,11 +2,11 @@
 void convert_to_tag_list(struct tag *tags);
 
 #ifdef CONFIG_ATAGS
-const struct machine_desc *setup_machine_tags(phys_addr_t __atags_pointer,
+const struct machine_desc *setup_machine_tags(void *__atags_vaddr,
 	unsigned int machine_nr);
 #else
 static inline const struct machine_desc * __init __noreturn
-setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
+setup_machine_tags(void *__atags_vaddr, unsigned int machine_nr)
 {
 	early_print("no ATAGS support: can't continue\n");
 	while (true);
diff --git a/arch/arm/kernel/atags_parse.c b/arch/arm/kernel/atags_parse.c
index 6c12d9fe694e..373b61f9a4f0 100644
--- a/arch/arm/kernel/atags_parse.c
+++ b/arch/arm/kernel/atags_parse.c
@@ -174,7 +174,7 @@ static void __init squash_mem_tags(struct tag *tag)
 }
 
 const struct machine_desc * __init
-setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
+setup_machine_tags(void *atags_vaddr, unsigned int machine_nr)
 {
 	struct tag *tags = (struct tag *)&default_tags;
 	const struct machine_desc *mdesc = NULL, *p;
@@ -195,8 +195,8 @@ setup_machine_tags(phys_addr_t __atags_pointer, unsigned int machine_nr)
 	if (!mdesc)
 		return NULL;
 
-	if (__atags_pointer)
-		tags = phys_to_virt(__atags_pointer);
+	if (atags_vaddr)
+		tags = atags_vaddr;
 	else if (mdesc->atag_offset)
 		tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
 
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 39c978698406..4e09883c276d 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -203,12 +203,12 @@ static const void * __init arch_get_next_mach(const char *const **match)
 
 /**
  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
- * @dt_phys: physical address of dt blob
+ * @dt_virt: virtual address of dt blob
  *
  * If a dtb was passed to the kernel in r2, then use it to choose the
  * correct machine_desc and to setup the system.
  */
-const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
+const struct machine_desc * __init setup_machine_fdt(void *dt_virt)
 {
 	const struct machine_desc *mdesc, *mdesc_best = NULL;
 
@@ -221,7 +221,7 @@ const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 	mdesc_best = &__mach_desc_GENERIC_DT;
 #endif
 
-	if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
+	if (!dt_virt || !early_init_dt_verify(dt_virt))
 		return NULL;
 
 	mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d8e18cdd96d3..0ea0172d0c6d 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -89,6 +89,7 @@ unsigned int cacheid __read_mostly;
 EXPORT_SYMBOL(cacheid);
 
 unsigned int __atags_pointer __initdata;
+void *atags_vaddr __initdata;
 
 unsigned int system_rev;
 EXPORT_SYMBOL(system_rev);
@@ -1075,19 +1076,22 @@ void __init hyp_mode_check(void)
 
 void __init setup_arch(char **cmdline_p)
 {
-	const struct machine_desc *mdesc;
+	const struct machine_desc *mdesc = NULL;
+
+	if (__atags_pointer)
+		atags_vaddr = phys_to_virt(__atags_pointer);
 
 	setup_processor();
-	mdesc = setup_machine_fdt(__atags_pointer);
+	if (atags_vaddr)
+		mdesc = setup_machine_fdt(atags_vaddr);
 	if (!mdesc)
-		mdesc = setup_machine_tags(__atags_pointer, __machine_arch_type);
+		mdesc = setup_machine_tags(atags_vaddr, __machine_arch_type);
 	if (!mdesc) {
 		early_print("\nError: invalid dtb and unrecognized/unsupported machine ID\n");
 		early_print("  r1=0x%08x, r2=0x%08x\n", __machine_arch_type,
 			    __atags_pointer);
 		if (__atags_pointer)
-			early_print("  r2[]=%*ph\n", 16,
-				    phys_to_virt(__atags_pointer));
+			early_print("  r2[]=%*ph\n", 16, atags_vaddr);
 		dump_machine_table();
 	}
 
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index c36f977b2ccb..0665a0dbd040 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1503,7 +1503,7 @@ static void __init map_lowmem(void)
 }
 
 #ifdef CONFIG_ARM_PV_FIXUP
-extern unsigned long __atags_pointer;
+extern void *atags_vaddr;
 typedef void pgtables_remap(long long offset, unsigned long pgd, void *bdata);
 pgtables_remap lpae_pgtables_remap_asm;
 
@@ -1534,7 +1534,7 @@ static void __init early_paging_init(const struct machine_desc *mdesc)
 	 */
 	lpae_pgtables_remap = (pgtables_remap *)(unsigned long)__pa(lpae_pgtables_remap_asm);
 	pa_pgd = __pa(swapper_pg_dir);
-	boot_data = __va(__atags_pointer);
+	boot_data = atags_vaddr;
 	barrier();
 
 	pr_info("Switching physical address space to 0x%08llx\n",
-- 
2.17.1

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