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arm: armv8: mmu: add mmu_unmap_reserved_mem

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For armv8, U-Boot uses a static map defined as 'mem_map' for configuring
the MMU's page tables, done by mmu_setup.

Though this works well for simpler platforms, it makes creating runtime
carveouts by modifying the static array at runtime exceedingly complex
like in mach-snapdragon/board.c.

Creation of such carveouts are much better handled by APIs such as
mmu_change_region_attr once the page tables are configured. Usually such
carveouts are configured via the device-tree's reserved-memory node
which provides the address and size for the carveout.

Therefore this patch adds mmu_unmap_reserved_mem which acts as a wrapper
over mmu_change_region_attr, helping unmap a reserved-memory region.

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Anshul Dalal <anshuld@ti.com>
Tested-by: Wadim Egorov <w.egorov@phytec.de>
This commit is contained in:
Anshul Dalal
2025-10-17 18:45:29 +05:30
committed by Tom Rini
parent f1c694b8fd
commit 856480eef0
2 changed files with 35 additions and 0 deletions
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26
arch/arm/cpu/armv8/cache_v8.c
View File

@@ -86,6 +86,32 @@ int mem_map_from_dram_banks(unsigned int index, unsigned int len, u64 attrs)
return 0;
}
int mmu_unmap_reserved_mem(const char *name, bool check_nomap)
{
void *fdt = (void *)gd->fdt_blob;
char node_path[128];
fdt_addr_t addr;
fdt_size_t size;
int ret;
snprintf(node_path, sizeof(node_path), "/reserved-memory/%s", name);
ret = fdt_path_offset(fdt, node_path);
if (ret < 0)
return ret;
if (check_nomap && !fdtdec_get_bool(fdt, ret, "no-map"))
return -EINVAL;
addr = fdtdec_get_addr_size(fdt, ret, "reg", &size);
if (addr == FDT_ADDR_T_NONE)
return -1;
mmu_change_region_attr_nobreak(addr, size, PTE_TYPE_FAULT);
return 0;
}
u64 get_tcr(u64 *pips, u64 *pva_bits)
{
int el = get_effective_el();

9
arch/arm/include/asm/armv8/mmu.h
View File

@@ -207,6 +207,15 @@ void setup_pgtables(void);
*/
int mem_map_from_dram_banks(unsigned int index, unsigned int len, u64 attrs);
/**
* mmu_unmap_reserved_mem() - Unmaps a reserved-memory node as PTE_TYPE_FAULT
* once MMU is configured by mmu_setup.
*
* @name: The name of the node under "/reserved-memory/" path
* @check_nomap: Check if the node is marked "no-map" before unmapping it
*/
int mmu_unmap_reserved_mem(const char *name, bool check_nomap);
u64 get_tcr(u64 *pips, u64 *pva_bits);
/**