Hi, Thomas,
On Thu, May 30, 2024 at 6:06 PM Thomas Weißschuh thomas@t-8ch.de wrote:
On 2024-05-22 23:02:17+0000, Jiaxun Yang wrote:
fdt_check_header(__dtb_start) will always success because kernel provided a dummy dtb, and by coincidence __dtb_start clashed with entry of this dummy dtb. The consequence is fdt passed from firmware will never be taken.
Fix by trying to utilise __dtb_start only when CONFIG_BUILTIN_DTB is enabled.
Cc: stable@vger.kernel.org Fixes: 7b937cc243e5 ("of: Create of_root if no dtb provided by firmware") Signed-off-by: Jiaxun Yang jiaxun.yang@flygoat.com
v3: Better reasoning in commit message, thanks Binbin and Huacai!
arch/loongarch/kernel/setup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c index 60e0fe97f61a..ea6d5db6c878 100644 --- a/arch/loongarch/kernel/setup.c +++ b/arch/loongarch/kernel/setup.c @@ -275,16 +275,18 @@ static void __init arch_reserve_crashkernel(void) static void __init fdt_setup(void) { #ifdef CONFIG_OF_EARLY_FLATTREE
void *fdt_pointer;
void *fdt_pointer = NULL; /* ACPI-based systems do not require parsing fdt */ if (acpi_os_get_root_pointer()) return;+#ifdef CONFIG_BUILTIN_DTB /* Prefer to use built-in dtb, checking its legality first. */ if (!fdt_check_header(__dtb_start)) fdt_pointer = __dtb_start;
else+#endif
if (!fdt_pointer) fdt_pointer = efi_fdt_pointer(); /* Fallback to firmware dtb */Prefer to use non-ifdef logic:
if (IS_ENABLED(CONFIG_BUILTIN_DTB) && !fdt_check_header(__dtb_start)) fdt_pointer = __dtb_start;This is shorter, easier to read and will prevent bitrot. The code will be typechecked but then optimized away, so no runtime overhead exists.
Good suggestion, I will take it.
Huacai
if (!fdt_pointer || fdt_check_header(fdt_pointer))-- 2.43.0