On Thu, May 23, 2024 at 6:03 AM Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> wrote:
>
> Currently kernel entry in head.S is in DMW address range,
> firmware is instructed to jump to this address after loading
> the image.
>
> However kernel should not make any assumption on firmware's
> DMW setting, thus the entry point should be a physical address
> falls into direct translation region.
>
> Fix by converting entry address to physical and amend entry
> calculation logic in libstub accordingly.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
> ---
> v2: Fix efistub
> v3: Move calculation to linker script
> ---
> arch/loongarch/kernel/head.S | 2 +-
> arch/loongarch/kernel/vmlinux.lds.S | 2 ++
> drivers/firmware/efi/libstub/loongarch.c | 2 +-
> 3 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index c4f7de2e2805..2cdc1ea808d9 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -22,7 +22,7 @@
> _head:
> .word MZ_MAGIC /* "MZ", MS-DOS header */
> .org 0x8
> - .dword kernel_entry /* Kernel entry point */
> + .dword _kernel_entry_phys /* Kernel entry point (physical address) */
> .dword _kernel_asize /* Kernel image effective size */
> .quad PHYS_LINK_KADDR /* Kernel image load offset from start of RAM */
> .org 0x38 /* 0x20 ~ 0x37 reserved */
> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
> index e8e97dbf9ca4..c6f89e51257a 100644
> --- a/arch/loongarch/kernel/vmlinux.lds.S
> +++ b/arch/loongarch/kernel/vmlinux.lds.S
> @@ -6,6 +6,7 @@
>
> #define PAGE_SIZE _PAGE_SIZE
> #define RO_EXCEPTION_TABLE_ALIGN 4
> +#define TO_PHYS_MASK 0x000fffffffffffff /* 48-bit */
>
> /*
> * Put .bss..swapper_pg_dir as the first thing in .bss. This will
> @@ -142,6 +143,7 @@ SECTIONS
>
> #ifdef CONFIG_EFI_STUB
> /* header symbols */
> + _kernel_entry_phys = kernel_entry & TO_PHYS_MASK;
- _kernel_entry_phys = kernel_entry & TO_PHYS_MASK;
+ _kernel_entry_phys = ABSOLUTE(kernel_entry & TO_PHYS_MASK);
> _kernel_asize = _end - _text;
> _kernel_fsize = _edata - _text;
> _kernel_vsize = _end - __initdata_begin;
> diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
> index 684c9354637c..60c145121393 100644
> --- a/drivers/firmware/efi/libstub/loongarch.c
> +++ b/drivers/firmware/efi/libstub/loongarch.c
> @@ -41,7 +41,7 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
> unsigned long __weak kernel_entry_address(unsigned long kernel_addr,
> efi_loaded_image_t *image)
> {
> - return *(unsigned long *)(kernel_addr + 8) - VMLINUX_LOAD_ADDRESS + kernel_addr;
> + return *(unsigned long *)(kernel_addr + 8) - TO_PHYS(VMLINUX_LOAD_ADDRESS) + kernel_addr;
> }
>
> efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
>
> --
> 2.43.0
>
>
- Rui
