Merge patch series "Fix XIP boot and make XIP testable in QEMU"

Frederik Haxel <haxel@fzi.de> says:

XIP boot seems to be broken for some time now. A likely reason why no one
seems to have noticed this is that XIP is more difficult to test, as it is
currently not easily testable with QEMU.

These patches fix the XIP boot and allow an XIP build without BUILTIN_DTB,
which in turn makes it easier to test an image with the QEMU virt machine.

* b4-shazam-merge:
  riscv: Allow disabling of BUILTIN_DTB for XIP
  riscv: Fixed wrong register in XIP_FIXUP_FLASH_OFFSET macro
  riscv: Make XIP bootable again

Link: https://lore.kernel.org/r/20231212130116.848530-1-haxel@fzi.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

4 files changed, 14 insertions, 7 deletions

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5e12582f66d4..19dfd521a52a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -905,13 +905,13 @@ config RISCV_ISA_FALLBACK
 	  on the replacement properties, "riscv,isa-base" and
 	  "riscv,isa-extensions".
 
-endmenu # "Boot options"
-
 config BUILTIN_DTB
-	bool
+	bool "Built-in device tree"
 	depends on OF && NONPORTABLE
 	default y if XIP_KERNEL
 
+endmenu # "Boot options"
+
 config PORTABLE
 	bool
 	default !NONPORTABLE
diff --git a/arch/riscv/include/asm/xip_fixup.h b/arch/riscv/include/asm/xip_fixup.h
index d4ffc3c37649..b65bf6306f69 100644
--- a/arch/riscv/include/asm/xip_fixup.h
+++ b/arch/riscv/include/asm/xip_fixup.h
@@ -13,7 +13,7 @@
         add \reg, \reg, t0
 .endm
 .macro XIP_FIXUP_FLASH_OFFSET reg
-	la t1, __data_loc
+	la t0, __data_loc
 	REG_L t1, _xip_phys_offset
 	sub \reg, \reg, t1
 	add \reg, \reg, t0
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 4bd9f7b398e8..4236a69c35cb 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -88,6 +88,7 @@ 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
 
@@ -264,10 +265,12 @@ SYM_CODE_START(_start_kernel)
 	la sp, _end + THREAD_SIZE
 	XIP_FIXUP_OFFSET sp
 	mv s0, a0
+	mv s1, a1
 	call __copy_data
 
-	/* Restore a0 copy */
+	/* Restore a0 & a1 copy */
 	mv a0, s0
+	mv a1, s1
 #endif
 
 #ifndef CONFIG_XIP_KERNEL
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2e011cbddf3a..a65937336cdc 100644
--- a/arch/riscv/mm/init.c
+++ b/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