(+ Steve)
On Mon, 2 Aug 2021 at 15:12, Benjamin Herrenschmidt
<benh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> We are currently allocating just enough memory for the file size,
> which means that the kernel BSS is in limbo (and not even zeroed).
>
> We are also not honoring the alignment specified in the image
> PE header.
>
> This makes us use the PE optional header in which the kernel puts the
> actual size it needs, including BSS, and make sure we clear it, and
> honors the specified alignment for the image.
>
> Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> ---
>
> This is v2 of the patch against Fedora/RH/Ubuntu grub2 (ie, fixes
> the original shim lock introduction patch) to address random crashes
> at boot on arm64.
>
> grub-core/loader/arm64/linux.c | 100 ++++++++++++++++++++++-----------
> 1 file changed, 66 insertions(+), 34 deletions(-)
>
> diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c
> index 47f8cf0d8..4a252d5e7 100644
> --- a/grub-core/loader/arm64/linux.c
> +++ b/grub-core/loader/arm64/linux.c
> @@ -41,6 +41,8 @@ GRUB_MOD_LICENSE ("GPLv3+");
> static grub_dl_t my_mod;
> static int loaded;
>
> +static void *kernel_alloc_addr;
> +static grub_uint32_t kernel_alloc_pages;
> static void *kernel_addr;
> static grub_uint64_t kernel_size;
> static grub_uint32_t handover_offset;
> @@ -204,9 +206,8 @@ grub_linux_unload (void)
> GRUB_EFI_BYTES_TO_PAGES (initrd_end - initrd_start));
> initrd_start = initrd_end = 0;
> grub_free (linux_args);
> - if (kernel_addr)
> - grub_efi_free_pages ((grub_addr_t) kernel_addr,
> - GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> + if (kernel_alloc_addr)
> + grub_efi_free_pages ((grub_addr_t) kernel_alloc_addr, kernel_alloc_pages);
> grub_fdt_unload ();
> return GRUB_ERR_NONE;
> }
> @@ -311,14 +312,35 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
> return grub_errno;
> }
>
> +static grub_err_t
> +parse_pe_header (void *kernel, grub_uint64_t *total_size,
> + grub_uint32_t *entry_offset,
> + grub_uint32_t *alignment)
> +{
> + struct linux_arch_kernel_header *lh = kernel;
> + struct grub_armxx_linux_pe_header *pe;
> +
> + pe = (void *)((unsigned long)kernel + lh->hdr_offset);
> +
> + if (pe->opt.magic != GRUB_PE32_PE64_MAGIC)
> + return grub_error(GRUB_ERR_BAD_OS, "Invalid PE optional header magic");
> +
> + *total_size = pe->opt.image_size;
> + *entry_offset = pe->opt.entry_addr;
> + *alignment = pe->opt.section_alignment;
> +
> + return GRUB_ERR_NONE;
> +}
> +
> static grub_err_t
> grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
> int argc, char *argv[])
> {
> grub_file_t file = 0;
> - struct linux_arch_kernel_header lh;
> - struct grub_armxx_linux_pe_header *pe;
> grub_err_t err;
> + grub_off_t filelen;
> + grub_uint32_t align;
> + void *kernel = NULL;
> int rc;
>
> grub_dl_ref (my_mod);
> @@ -333,40 +355,24 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
> if (!file)
> goto fail;
>
> - kernel_size = grub_file_size (file);
> -
> - if (grub_file_read (file, &lh, sizeof (lh)) < (long) sizeof (lh))
> - return grub_errno;
> -
> - if (grub_arch_efi_linux_check_image (&lh) != GRUB_ERR_NONE)
> - goto fail;
> -
> - grub_loader_unset();
> -
> - grub_dprintf ("linux", "kernel file size: %lld\n", (long long) kernel_size);
> - kernel_addr = grub_efi_allocate_any_pages (GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> - grub_dprintf ("linux", "kernel numpages: %lld\n",
> - (long long) GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> - if (!kernel_addr)
> + filelen = grub_file_size (file);
> + kernel = grub_malloc(filelen);
> + if (!kernel)
> {
> - grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> + grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("cannot allocate kernel load buffer"));
> goto fail;
> }
>
> - grub_file_seek (file, 0);
> - if (grub_file_read (file, kernel_addr, kernel_size)
> - < (grub_int64_t) kernel_size)
> + if (grub_file_read (file, kernel, filelen) < (grub_ssize_t)filelen)
> {
> - if (!grub_errno)
> - grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"), argv[0]);
> + grub_error (GRUB_ERR_FILE_READ_ERROR, N_("Can't read kernel %s"),
> + argv[0]);
> goto fail;
> }
>
> - grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
> -
> if (grub_efi_get_secureboot () == GRUB_EFI_SECUREBOOT_MODE_ENABLED)
> {
> - rc = grub_linuxefi_secure_validate (kernel_addr, kernel_size);
> + rc = grub_linuxefi_secure_validate (kernel, filelen);
> if (rc <= 0)
> {
> grub_error (GRUB_ERR_INVALID_COMMAND,
> @@ -375,8 +381,32 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
> }
> }
>
> - pe = (void *)((unsigned long)kernel_addr + lh.hdr_offset);
> - handover_offset = pe->opt.entry_addr;
> + if (grub_arch_efi_linux_check_image (kernel) != GRUB_ERR_NONE)
> + goto fail;
> + if (parse_pe_header (kernel, &kernel_size, &handover_offset, &align) != GRUB_ERR_NONE)
> + goto fail;
> + grub_dprintf ("linux", "kernel mem size : %lld\n", (long long) kernel_size);
> + grub_dprintf ("linux", "kernel entry offset : %d\n", handover_offset);
> + grub_dprintf ("linux", "kernel alignment : 0x%x\n", align);
> +
> + grub_loader_unset();
> +
> + kernel_alloc_pages = GRUB_EFI_BYTES_TO_PAGES (kernel_size + align - 1);
> + kernel_alloc_addr = grub_efi_allocate_any_pages (kernel_alloc_pages);
> + grub_dprintf ("linux", "kernel numpages: %d\n", kernel_alloc_pages);
> + if (!kernel_alloc_addr)
> + {
> + grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> + goto fail;
> + }
> + kernel_addr = (void *)ALIGN_UP((grub_uint64_t)kernel_alloc_addr, align);
> +
> + grub_dprintf ("linux", "kernel @ %p\n", kernel_addr);
> + grub_memcpy (kernel_addr, kernel, grub_min(filelen, kernel_size));
> + if (kernel_size > filelen)
> + grub_memset ((char *)kernel_addr + filelen, 0, kernel_size - filelen);
> + grub_free(kernel);
> + kernel = NULL;
>
> cmdline_size = grub_loader_cmdline_size (argc, argv) + sizeof (LINUX_IMAGE);
> linux_args = grub_malloc (cmdline_size);
> @@ -400,6 +430,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
> }
>
> fail:
> + if (kernel)
> + grub_free (kernel);
> +
> if (file)
> grub_file_close (file);
>
> @@ -412,9 +445,8 @@ fail:
> if (linux_args && !loaded)
> grub_free (linux_args);
>
> - if (kernel_addr && !loaded)
> - grub_efi_free_pages ((grub_addr_t) kernel_addr,
> - GRUB_EFI_BYTES_TO_PAGES (kernel_size));
> + if (kernel_alloc_addr && !loaded)
> + grub_efi_free_pages ((grub_addr_t) kernel_alloc_addr, kernel_alloc_pages);
>
> return grub_errno;
> }
> --
> 2.25.1
>
>
