efi/loongarch: Don't jump to kernel entry via the old image

Currently, the EFI entry code for LoongArch is set up to copy the
executable image to the preferred offset, but instead of branching
directly into that image, it branches to the local copy of kernel_entry,
and relies on the logic in that function to switch to the link time
address instead.

This is a bit sloppy, and not something we can support once we merge the
EFI decompressor with the EFI stub. So let's clean this up a bit, by
adding a helper that computes the offset of kernel_entry from the start
of the image, and simply adding the result to VMLINUX_LOAD_ADDRESS.

And considering that we cannot execute from anywhere else anyway, let's
avoid efi_relocate_kernel() and just allocate the pages instead.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/efi.h
index 5a470c8d2bbc64e2bbde8a3c517603cb68e81da1..97f16e60c6ff2f2e76aa29f36847a5ca4b6e35b9 100644 (file)
--- a/arch/loongarch/include/asm/efi.h
+++ b/arch/loongarch/include/asm/efi.h
@@ -31,4 +31,6 @@ static inline unsigned long efi_get_kimg_min_align(void)
 
 #define EFI_KIMG_PREFERRED_ADDRESS     PHYSADDR(VMLINUX_LOAD_ADDRESS)
 
+unsigned long kernel_entry_address(void);
+
 #endif /* _ASM_LOONGARCH_EFI_H */

diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
index a2e55e5c400309f37ce82bc37f000cd69139e405..6b30fc281458b7ed77b2e5bdad7213c6dbee048b 100644 (file)
--- a/drivers/firmware/efi/libstub/loongarch-stub.c
+++ b/drivers/firmware/efi/libstub/loongarch-stub.c
@@ -29,18 +29,27 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
                                 efi_loaded_image_t *image,
                                 efi_handle_t image_handle)
 {
+       int nr_pages = round_up(kernel_asize, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
+       efi_physical_addr_t kernel_addr = EFI_KIMG_PREFERRED_ADDRESS;
        efi_status_t status;
-       unsigned long kernel_addr = 0;
 
-       kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
-
-       status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
-                                    EFI_KIMG_PREFERRED_ADDRESS,
-                                    efi_get_kimg_min_align(), 0x0);
+       /*
+        * Allocate space for the kernel image at the preferred offset. This is
+        * the only location in memory from where we can execute the image, so
+        * no point in falling back to another allocation.
+        */
+       status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+                            EFI_LOADER_DATA, nr_pages, &kernel_addr);
+       if (status != EFI_SUCCESS)
+               return status;
 
-       *image_addr = kernel_addr;
+       *image_addr = EFI_KIMG_PREFERRED_ADDRESS;
        *image_size = kernel_asize;
 
+       memcpy((void *)EFI_KIMG_PREFERRED_ADDRESS,
+              (void *)&kernel_offset - kernel_offset,
+              kernel_fsize);
+
        return status;
 }
 
@@ -64,6 +73,13 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
        return EFI_SUCCESS;
 }
 
+unsigned long kernel_entry_address(void)
+{
+       unsigned long base = (unsigned long)&kernel_offset - kernel_offset;
+
+       return (unsigned long)&kernel_entry - base + VMLINUX_LOAD_ADDRESS;
+}
+
 efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
                             unsigned long kernel_addr, char *cmdline_ptr)
 {
@@ -95,8 +111,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
        csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
        csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
 
-       real_kernel_entry = (kernel_entry_t)
-               ((unsigned long)&kernel_entry - kernel_addr + VMLINUX_LOAD_ADDRESS);
+       real_kernel_entry = (void *)kernel_entry_address();
 
        real_kernel_entry(true, (unsigned long)cmdline_ptr,
                          (unsigned long)efi_system_table);