riscv: drop the use of XIP_OFFSET in create_kernel_page_table()

XIP_OFFSET is the hard-coded offset of writable data section within the
kernel.

By hard-coding this value, the read-only section of the kernel (which is
placed before the writable data section) is restricted in size.

As a preparation to remove this hard-coded value entirely, stop using
XIP_OFFSET in create_kernel_page_table(). Instead use _sdata and _start to
do the same thing.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/4ea3f222a7eb9f91c04b155ff2e4d3ef19158acc.1717789719.git.namcao@linutronix.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c2d63808d7abf9e2d9b7fd2d7cf7d0b7f728822a..31b23f84494f40e76b441818fd5d429cbf20be2a 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -917,7 +917,7 @@ static void __init relocate_kernel(void)
 static void __init create_kernel_page_table(pgd_t *pgdir,
                                            __always_unused bool early)
 {
-       uintptr_t va, end_va;
+       uintptr_t va, start_va, end_va;
 
        /* Map the flash resident part */
        end_va = kernel_map.virt_addr + kernel_map.xiprom_sz;
@@ -927,10 +927,11 @@ static void __init create_kernel_page_table(pgd_t *pgdir,
                                   PMD_SIZE, PAGE_KERNEL_EXEC);
 
        /* Map the data in RAM */
+       start_va = kernel_map.virt_addr + (uintptr_t)&_sdata - (uintptr_t)&_start;
        end_va = kernel_map.virt_addr + kernel_map.size;
-       for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
+       for (va = start_va; va < end_va; va += PMD_SIZE)
                create_pgd_mapping(pgdir, va,
-                                  kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
+                                  kernel_map.phys_addr + (va - start_va),
                                   PMD_SIZE, PAGE_KERNEL);
 }
 #else