* [PATCH v2 2/3] arm64: mm: Make map_fdt() return mapped pointer
2025-09-04 0:52 [PATCH v2 0/3] Type correctness cleanup for ARM64 MMU initialization Sam Edwards
2025-09-04 0:52 ` [PATCH v2 1/3] arm64: mm: Cast start/end markers to char *, not u64 Sam Edwards
@ 2025-09-04 0:52 ` Sam Edwards
2025-09-04 0:52 ` [PATCH v2 3/3] arm64: mm: Represent physical memory with phys_addr_t and resource_size_t Sam Edwards
2025-09-16 21:13 ` [PATCH v2 0/3] Type correctness cleanup for ARM64 MMU initialization Will Deacon
3 siblings, 0 replies; 5+ messages in thread
From: Sam Edwards @ 2025-09-04 0:52 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon, Marc Zyngier
Cc: Andrew Morton, Anshuman Khandual, Ard Biesheuvel, Ryan Roberts,
Baruch Siach, Kevin Brodsky, Joey Gouly, linux-arm-kernel,
linux-kernel, Sam Edwards
Currently map_fdt() accepts a physical address and relies on the caller
to keep using the same value after mapping, since the implementation
happens to install an identity mapping. This obscures the fact that the
usable pointer is defined by the mapping, not by the input value. Since
the mapping determines pointer validity, it is more natural to produce
the pointer at mapping time.
Change map_fdt() to return a void * pointing to the mapped FDT. This
clarifies the data flow, removes the implicit identity assumption, and
prepares for making map_fdt() accept a phys_addr_t in a follow-up
change.
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
---
arch/arm64/kernel/pi/map_kernel.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/kernel/pi/map_kernel.c b/arch/arm64/kernel/pi/map_kernel.c
index 2b3047860230..5dc4107b5a7f 100644
--- a/arch/arm64/kernel/pi/map_kernel.c
+++ b/arch/arm64/kernel/pi/map_kernel.c
@@ -191,7 +191,7 @@ static void __init remap_idmap_for_lpa2(void)
memset(init_pg_dir, 0, (char *)init_pg_end - (char *)init_pg_dir);
}
-static void __init map_fdt(u64 fdt)
+static void *__init map_fdt(u64 fdt)
{
static u8 ptes[INIT_IDMAP_FDT_SIZE] __initdata __aligned(PAGE_SIZE);
u64 efdt = fdt + MAX_FDT_SIZE;
@@ -205,6 +205,8 @@ static void __init map_fdt(u64 fdt)
fdt, PAGE_KERNEL, IDMAP_ROOT_LEVEL,
(pte_t *)init_idmap_pg_dir, false, 0);
dsb(ishst);
+
+ return (void *)fdt;
}
/*
@@ -238,15 +240,14 @@ asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt)
int root_level = 4 - CONFIG_PGTABLE_LEVELS;
int va_bits = VA_BITS;
int chosen;
-
- map_fdt((u64)fdt);
+ void *fdt_mapped = map_fdt((u64)fdt);
/* Clear BSS and the initial page tables */
memset(__bss_start, 0, (char *)init_pg_end - (char *)__bss_start);
/* Parse the command line for CPU feature overrides */
- chosen = fdt_path_offset(fdt, chosen_str);
- init_feature_override(boot_status, fdt, chosen);
+ chosen = fdt_path_offset(fdt_mapped, chosen_str);
+ init_feature_override(boot_status, fdt_mapped, chosen);
if (IS_ENABLED(CONFIG_ARM64_64K_PAGES) && !cpu_has_lva()) {
va_bits = VA_BITS_MIN;
@@ -266,7 +267,7 @@ asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt)
* fill in the high bits from the seed.
*/
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
- u64 kaslr_seed = kaslr_early_init(fdt, chosen);
+ u64 kaslr_seed = kaslr_early_init(fdt_mapped, chosen);
if (kaslr_seed && kaslr_requires_kpti())
arm64_use_ng_mappings = ng_mappings_allowed();
--
2.49.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 3/3] arm64: mm: Represent physical memory with phys_addr_t and resource_size_t
2025-09-04 0:52 [PATCH v2 0/3] Type correctness cleanup for ARM64 MMU initialization Sam Edwards
2025-09-04 0:52 ` [PATCH v2 1/3] arm64: mm: Cast start/end markers to char *, not u64 Sam Edwards
2025-09-04 0:52 ` [PATCH v2 2/3] arm64: mm: Make map_fdt() return mapped pointer Sam Edwards
@ 2025-09-04 0:52 ` Sam Edwards
2025-09-16 21:13 ` [PATCH v2 0/3] Type correctness cleanup for ARM64 MMU initialization Will Deacon
3 siblings, 0 replies; 5+ messages in thread
From: Sam Edwards @ 2025-09-04 0:52 UTC (permalink / raw)
To: Catalin Marinas, Will Deacon, Marc Zyngier
Cc: Andrew Morton, Anshuman Khandual, Ard Biesheuvel, Ryan Roberts,
Baruch Siach, Kevin Brodsky, Joey Gouly, linux-arm-kernel,
linux-kernel, Sam Edwards
This is a type-correctness cleanup to MMU/boot code that replaces
several instances of void * and u64 with phys_addr_t (to represent
addresses) and resource_size_t (to represent sizes) to emphasize that
the code in question concerns physical memory specifically.
The rationale for this change is to improve clarity and readability in
a few modules that handle both types (physical and virtual) of address
and differentiation is essential.
I have left u64 in cases where the address may be either physical or
virtual, where the address is exclusively virtual but used in heavy
pointer arithmetic, and in cases I may have overlooked. I do not
necessarily consider u64 the ideal type in those situations, but it
avoids breaking existing semantics in this cleanup.
This patch provably has no effect at runtime: I have verified that
.text of vmlinux is identical after this change.
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
---
arch/arm64/kernel/pi/map_kernel.c | 26 +++++++++++++-------------
arch/arm64/kernel/pi/map_range.c | 20 ++++++++++++--------
arch/arm64/kernel/pi/pi.h | 9 +++++----
arch/arm64/mm/init.c | 6 +++---
arch/arm64/mm/mmu.c | 17 +++++++++--------
5 files changed, 42 insertions(+), 36 deletions(-)
diff --git a/arch/arm64/kernel/pi/map_kernel.c b/arch/arm64/kernel/pi/map_kernel.c
index 5dc4107b5a7f..e6d35eff1486 100644
--- a/arch/arm64/kernel/pi/map_kernel.c
+++ b/arch/arm64/kernel/pi/map_kernel.c
@@ -18,9 +18,9 @@
extern const u8 __eh_frame_start[], __eh_frame_end[];
-extern void idmap_cpu_replace_ttbr1(void *pgdir);
+extern void idmap_cpu_replace_ttbr1(phys_addr_t pgdir);
-static void __init map_segment(pgd_t *pg_dir, u64 *pgd, u64 va_offset,
+static void __init map_segment(pgd_t *pg_dir, phys_addr_t *pgd, u64 va_offset,
void *start, void *end, pgprot_t prot,
bool may_use_cont, int root_level)
{
@@ -40,7 +40,7 @@ static void __init map_kernel(u64 kaslr_offset, u64 va_offset, int root_level)
{
bool enable_scs = IS_ENABLED(CONFIG_UNWIND_PATCH_PAC_INTO_SCS);
bool twopass = IS_ENABLED(CONFIG_RELOCATABLE);
- u64 pgdp = (u64)init_pg_dir + PAGE_SIZE;
+ phys_addr_t pgdp = (phys_addr_t)init_pg_dir + PAGE_SIZE;
pgprot_t text_prot = PAGE_KERNEL_ROX;
pgprot_t data_prot = PAGE_KERNEL;
pgprot_t prot;
@@ -90,7 +90,7 @@ static void __init map_kernel(u64 kaslr_offset, u64 va_offset, int root_level)
true, root_level);
dsb(ishst);
- idmap_cpu_replace_ttbr1(init_pg_dir);
+ idmap_cpu_replace_ttbr1((phys_addr_t)init_pg_dir);
if (twopass) {
if (IS_ENABLED(CONFIG_RELOCATABLE))
@@ -129,10 +129,10 @@ static void __init map_kernel(u64 kaslr_offset, u64 va_offset, int root_level)
/* Copy the root page table to its final location */
memcpy((void *)swapper_pg_dir + va_offset, init_pg_dir, PAGE_SIZE);
dsb(ishst);
- idmap_cpu_replace_ttbr1(swapper_pg_dir);
+ idmap_cpu_replace_ttbr1((phys_addr_t)swapper_pg_dir);
}
-static void noinline __section(".idmap.text") set_ttbr0_for_lpa2(u64 ttbr)
+static void noinline __section(".idmap.text") set_ttbr0_for_lpa2(phys_addr_t ttbr)
{
u64 sctlr = read_sysreg(sctlr_el1);
u64 tcr = read_sysreg(tcr_el1) | TCR_DS;
@@ -172,7 +172,7 @@ static void __init remap_idmap_for_lpa2(void)
*/
create_init_idmap(init_pg_dir, mask);
dsb(ishst);
- set_ttbr0_for_lpa2((u64)init_pg_dir);
+ set_ttbr0_for_lpa2((phys_addr_t)init_pg_dir);
/*
* Recreate the initial ID map with the same granularity as before.
@@ -185,17 +185,17 @@ static void __init remap_idmap_for_lpa2(void)
dsb(ishst);
/* switch back to the updated initial ID map */
- set_ttbr0_for_lpa2((u64)init_idmap_pg_dir);
+ set_ttbr0_for_lpa2((phys_addr_t)init_idmap_pg_dir);
/* wipe the temporary ID map from memory */
memset(init_pg_dir, 0, (char *)init_pg_end - (char *)init_pg_dir);
}
-static void *__init map_fdt(u64 fdt)
+static void *__init map_fdt(phys_addr_t fdt)
{
static u8 ptes[INIT_IDMAP_FDT_SIZE] __initdata __aligned(PAGE_SIZE);
- u64 efdt = fdt + MAX_FDT_SIZE;
- u64 ptep = (u64)ptes;
+ phys_addr_t efdt = fdt + MAX_FDT_SIZE;
+ phys_addr_t ptep = (phys_addr_t)ptes; /* We're idmapped when called */
/*
* Map up to MAX_FDT_SIZE bytes, but avoid overlap with
@@ -232,7 +232,7 @@ static bool __init ng_mappings_allowed(void)
return true;
}
-asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt)
+asmlinkage void __init early_map_kernel(u64 boot_status, phys_addr_t fdt)
{
static char const chosen_str[] __initconst = "/chosen";
u64 va_base, pa_base = (u64)&_text;
@@ -240,7 +240,7 @@ asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt)
int root_level = 4 - CONFIG_PGTABLE_LEVELS;
int va_bits = VA_BITS;
int chosen;
- void *fdt_mapped = map_fdt((u64)fdt);
+ void *fdt_mapped = map_fdt(fdt);
/* Clear BSS and the initial page tables */
memset(__bss_start, 0, (char *)init_pg_end - (char *)__bss_start);
diff --git a/arch/arm64/kernel/pi/map_range.c b/arch/arm64/kernel/pi/map_range.c
index 7982788e7b9a..de52cd85c691 100644
--- a/arch/arm64/kernel/pi/map_range.c
+++ b/arch/arm64/kernel/pi/map_range.c
@@ -26,8 +26,9 @@
* @va_offset: Offset between a physical page and its current mapping
* in the VA space
*/
-void __init map_range(u64 *pte, u64 start, u64 end, u64 pa, pgprot_t prot,
- int level, pte_t *tbl, bool may_use_cont, u64 va_offset)
+void __init map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
+ pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,
+ u64 va_offset)
{
u64 cmask = (level == 3) ? CONT_PTE_SIZE - 1 : U64_MAX;
ptdesc_t protval = pgprot_val(prot) & ~PTE_TYPE_MASK;
@@ -87,19 +88,22 @@ void __init map_range(u64 *pte, u64 start, u64 end, u64 pa, pgprot_t prot,
}
}
-asmlinkage u64 __init create_init_idmap(pgd_t *pg_dir, ptdesc_t clrmask)
+asmlinkage phys_addr_t __init create_init_idmap(pgd_t *pg_dir, ptdesc_t clrmask)
{
- u64 ptep = (u64)pg_dir + PAGE_SIZE;
+ phys_addr_t ptep = (phys_addr_t)pg_dir + PAGE_SIZE; /* MMU is off */
pgprot_t text_prot = PAGE_KERNEL_ROX;
pgprot_t data_prot = PAGE_KERNEL;
pgprot_val(text_prot) &= ~clrmask;
pgprot_val(data_prot) &= ~clrmask;
- map_range(&ptep, (u64)_stext, (u64)__initdata_begin, (u64)_stext,
- text_prot, IDMAP_ROOT_LEVEL, (pte_t *)pg_dir, false, 0);
- map_range(&ptep, (u64)__initdata_begin, (u64)_end, (u64)__initdata_begin,
- data_prot, IDMAP_ROOT_LEVEL, (pte_t *)pg_dir, false, 0);
+ /* MMU is off; pointer casts to phys_addr_t are safe */
+ map_range(&ptep, (u64)_stext, (u64)__initdata_begin,
+ (phys_addr_t)_stext, text_prot, IDMAP_ROOT_LEVEL,
+ (pte_t *)pg_dir, false, 0);
+ map_range(&ptep, (u64)__initdata_begin, (u64)_end,
+ (phys_addr_t)__initdata_begin, data_prot, IDMAP_ROOT_LEVEL,
+ (pte_t *)pg_dir, false, 0);
return ptep;
}
diff --git a/arch/arm64/kernel/pi/pi.h b/arch/arm64/kernel/pi/pi.h
index 46cafee7829f..08ef9f80456b 100644
--- a/arch/arm64/kernel/pi/pi.h
+++ b/arch/arm64/kernel/pi/pi.h
@@ -29,9 +29,10 @@ u64 kaslr_early_init(void *fdt, int chosen);
void relocate_kernel(u64 offset);
int scs_patch(const u8 eh_frame[], int size);
-void map_range(u64 *pgd, u64 start, u64 end, u64 pa, pgprot_t prot,
- int level, pte_t *tbl, bool may_use_cont, u64 va_offset);
+void map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
+ pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,
+ u64 va_offset);
-asmlinkage void early_map_kernel(u64 boot_status, void *fdt);
+asmlinkage void early_map_kernel(u64 boot_status, phys_addr_t fdt);
-asmlinkage u64 create_init_idmap(pgd_t *pgd, ptdesc_t clrmask);
+asmlinkage phys_addr_t create_init_idmap(pgd_t *pgd, ptdesc_t clrmask);
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index ea84a61ed508..70c2ca813c18 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -243,7 +243,7 @@ void __init arm64_memblock_init(void)
*/
if (memory_limit != PHYS_ADDR_MAX) {
memblock_mem_limit_remove_map(memory_limit);
- memblock_add(__pa_symbol(_text), (u64)(_end - _text));
+ memblock_add(__pa_symbol(_text), (resource_size_t)(_end - _text));
}
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
@@ -252,8 +252,8 @@ void __init arm64_memblock_init(void)
* initrd to become inaccessible via the linear mapping.
* Otherwise, this is a no-op
*/
- u64 base = phys_initrd_start & PAGE_MASK;
- u64 size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base;
+ phys_addr_t base = phys_initrd_start & PAGE_MASK;
+ resource_size_t size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base;
/*
* We can only add back the initrd memory if we don't end up
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 34e5d78af076..de463040582c 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -794,17 +794,18 @@ static void __init declare_kernel_vmas(void)
declare_vma(&vmlinux_seg[4], _data, _end, 0);
}
-void __pi_map_range(u64 *pgd, u64 start, u64 end, u64 pa, pgprot_t prot,
- int level, pte_t *tbl, bool may_use_cont, u64 va_offset);
+void __pi_map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
+ pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,
+ u64 va_offset);
static u8 idmap_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init,
kpti_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init;
static void __init create_idmap(void)
{
- u64 start = __pa_symbol(__idmap_text_start);
- u64 end = __pa_symbol(__idmap_text_end);
- u64 ptep = __pa_symbol(idmap_ptes);
+ phys_addr_t start = __pa_symbol(__idmap_text_start);
+ phys_addr_t end = __pa_symbol(__idmap_text_end);
+ phys_addr_t ptep = __pa_symbol(idmap_ptes);
__pi_map_range(&ptep, start, end, start, PAGE_KERNEL_ROX,
IDMAP_ROOT_LEVEL, (pte_t *)idmap_pg_dir, false,
@@ -812,7 +813,7 @@ static void __init create_idmap(void)
if (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) && !arm64_use_ng_mappings) {
extern u32 __idmap_kpti_flag;
- u64 pa = __pa_symbol(&__idmap_kpti_flag);
+ phys_addr_t pa = __pa_symbol(&__idmap_kpti_flag);
/*
* The KPTI G-to-nG conversion code needs a read-write mapping
@@ -1331,8 +1332,8 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
struct range arch_get_mappable_range(void)
{
struct range mhp_range;
- u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
- u64 end_linear_pa = __pa(PAGE_END - 1);
+ phys_addr_t start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
+ phys_addr_t end_linear_pa = __pa(PAGE_END - 1);
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
/*
--
2.49.1
^ permalink raw reply related [flat|nested] 5+ messages in thread