Hi,
On 1/5/26 9:47 AM, Ahmad Fatoum wrote:
> To allow generic code to remap memory as read-only, let's add the
> definition to the global header.
>
> On platforms other than ARM, mapping R/O will just be cached R/W.
>
> Signed-off-by: Ahmad Fatoum <[email protected]>
Please disregard in favor of Sascha's version. I think it's better to
just let it fail on unsupported architectures instead of mapping it to
MAP_CACHED.
Cheers,
Ahmad
> ---
> arch/Kconfig | 3 +++
> arch/arm/Kconfig | 1 +
> arch/arm/cpu/mmu-common.c | 4 ++--
> arch/arm/cpu/mmu-common.h | 3 +--
> arch/arm/cpu/mmu_32.c | 4 ++--
> arch/arm/cpu/mmu_64.c | 2 +-
> include/mmu.h | 6 ++++++
> 7 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index ca9aa25a9c4b..3daba5239740 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -62,6 +62,9 @@ config ARCH_DMA_DEFAULT_COHERENT
> config ARCH_HAS_DMA_WRITE_COMBINE
> bool
>
> +config ARCH_HAS_RO_MAPPINGS
> + bool
> +
> config ARCH_HAS_ASAN_FIBER_API
> bool
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 5123e9b1402c..d9b1f5de1fa7 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -17,6 +17,7 @@ config ARM
> select HAVE_ARCH_BOOTM_OFTREE
> select HW_HAS_PCI
> select ARCH_HAS_DMA_WRITE_COMBINE
> + select ARCH_HAS_RO_MAPPINGS
> select HAVE_EFI_LOADER if MMU # for payload unaligned accesses
> default y
>
> diff --git a/arch/arm/cpu/mmu-common.c b/arch/arm/cpu/mmu-common.c
> index a1431c0ff461..6db85fa9c7d4 100644
> --- a/arch/arm/cpu/mmu-common.c
> +++ b/arch/arm/cpu/mmu-common.c
> @@ -22,7 +22,7 @@ const char *map_type_tostr(maptype_t map_type)
>
> switch (map_type) {
> case ARCH_MAP_CACHED_RWX: return "RWX";
> - case ARCH_MAP_CACHED_RO: return "RO";
> + case MAP_RO: return "RO";
> case MAP_CACHED: return "CACHED";
> case MAP_UNCACHED: return "UNCACHED";
> case MAP_CODE: return "CODE";
> @@ -158,7 +158,7 @@ static void mmu_remap_memory_banks(void)
> }
>
> remap_range((void *)code_start, code_size, MAP_CODE);
> - remap_range((void *)rodata_start, rodata_size, ARCH_MAP_CACHED_RO);
> + remap_range((void *)rodata_start, rodata_size, MAP_RO);
>
> setup_trap_pages();
> }
> diff --git a/arch/arm/cpu/mmu-common.h b/arch/arm/cpu/mmu-common.h
> index a111e15a21b4..39332d8f5a98 100644
> --- a/arch/arm/cpu/mmu-common.h
> +++ b/arch/arm/cpu/mmu-common.h
> @@ -12,7 +12,6 @@
> #include <linux/bits.h>
>
> #define ARCH_MAP_CACHED_RWX MAP_ARCH(2)
> -#define ARCH_MAP_CACHED_RO MAP_ARCH(3)
>
> #define ARCH_MAP_FLAG_PAGEWISE BIT(31)
>
> @@ -32,7 +31,7 @@ static inline maptype_t
> arm_mmu_maybe_skip_permissions(maptype_t map_type)
> switch (map_type & MAP_TYPE_MASK) {
> case MAP_CODE:
> case MAP_CACHED:
> - case ARCH_MAP_CACHED_RO:
> + case MAP_RO:
> return ARCH_MAP_CACHED_RWX;
> default:
> return map_type;
> diff --git a/arch/arm/cpu/mmu_32.c b/arch/arm/cpu/mmu_32.c
> index 912d14e8cf82..d41ebcfb7fe4 100644
> --- a/arch/arm/cpu/mmu_32.c
> +++ b/arch/arm/cpu/mmu_32.c
> @@ -304,7 +304,7 @@ static uint32_t get_pte_flags(maptype_t map_type)
> switch (map_type & MAP_TYPE_MASK) {
> case ARCH_MAP_CACHED_RWX:
> return PTE_FLAGS_CACHED_V7_RWX;
> - case ARCH_MAP_CACHED_RO:
> + case MAP_RO:
> return PTE_FLAGS_CACHED_RO_V7;
> case MAP_CACHED:
> return PTE_FLAGS_CACHED_V7;
> @@ -320,7 +320,7 @@ static uint32_t get_pte_flags(maptype_t map_type)
> }
> } else {
> switch (map_type & MAP_TYPE_MASK) {
> - case ARCH_MAP_CACHED_RO:
> + case MAP_RO:
> case MAP_CODE:
> return PTE_FLAGS_CACHED_RO_V4;
> case ARCH_MAP_CACHED_RWX:
> diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
> index 56c6a21f2b2a..006b2b29478f 100644
> --- a/arch/arm/cpu/mmu_64.c
> +++ b/arch/arm/cpu/mmu_64.c
> @@ -159,7 +159,7 @@ static unsigned long get_pte_attrs(maptype_t map_type)
> return attrs_xn() | MEM_ALLOC_WRITECOMBINE;
> case MAP_CODE:
> return CACHED_MEM | PTE_BLOCK_RO;
> - case ARCH_MAP_CACHED_RO:
> + case MAP_RO:
> return attrs_xn() | CACHED_MEM | PTE_BLOCK_RO;
> case ARCH_MAP_CACHED_RWX:
> return CACHED_MEM;
> diff --git a/include/mmu.h b/include/mmu.h
> index f79619808829..7d87885a5cb4 100644
> --- a/include/mmu.h
> +++ b/include/mmu.h
> @@ -16,6 +16,12 @@
> #define MAP_WRITECOMBINE MAP_UNCACHED
> #endif
>
> +#ifdef CONFIG_ARCH_HAS_RO_MAPPINGS
> +#define MAP_RO 5
> +#else
> +#define MAP_RO MAP_CACHED
> +#endif
> +
> #define MAP_TYPE_MASK 0xFFFF
> #define MAP_ARCH(x) ((u16)~(x))
>
--
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