riscv: Make XIP bootable again

Currently, the XIP kernel seems to fail to boot due to missing
XIP_FIXUP and a wrong page_offset value. A superfluous XIP_FIXUP
has also been removed.

Signed-off-by: Frederik Haxel <haxel@fzi.de>
Link: https://lore.kernel.org/r/20231212130116.848530-2-haxel@fzi.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: fzi-haxel

arch/riscv/kernel/head.S

@@ -89,6 +89,7 @@ relocate_enable_mmu:
 	/* Compute satp for kernel page tables, but don't load it yet */
 	srl a2, a0, PAGE_SHIFT
 	la a1, satp_mode
+	XIP_FIXUP_OFFSET a1
 	REG_L a1, 0(a1)
 	or a2, a2, a1
 

arch/riscv/mm/init.c

@@ -174,6 +174,9 @@ void __init mem_init(void)
 
 /* Limit the memory size via mem. */
 static phys_addr_t memory_limit;
+#ifdef CONFIG_XIP_KERNEL
+#define memory_limit	(*(phys_addr_t *)XIP_FIXUP(&memory_limit))
+#endif /* CONFIG_XIP_KERNEL */
 
 static int __init early_mem(char *p)
 {
@@ -952,7 +955,7 @@ static void __init create_fdt_early_page_table(uintptr_t fix_fdt_va,
 	 * setup_vm_final installs the linear mapping. For 32-bit kernel, as the
 	 * kernel is mapped in the linear mapping, that makes no difference.
 	 */
-	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
+	dtb_early_va = kernel_mapping_pa_to_va(dtb_pa);
 #endif
 
 	dtb_early_pa = dtb_pa;
@@ -1055,9 +1058,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 #endif
 
 	kernel_map.virt_addr = KERNEL_LINK_ADDR + kernel_map.virt_offset;
-	kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
 
 #ifdef CONFIG_XIP_KERNEL
+	kernel_map.page_offset = PAGE_OFFSET_L3;
 	kernel_map.xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
 	kernel_map.xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);
 
@@ -1067,6 +1070,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 
 	kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom;
 #else
+	kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
 	kernel_map.phys_addr = (uintptr_t)(&_start);
 	kernel_map.size = (uintptr_t)(&_end) - kernel_map.phys_addr;
 #endif