On Tue, 3 Mar 2020 at 23:12, Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote: > > This series adds the ability to use the entire PE image space for > decompression, provides the preferred address to the PE loader via the > header, and finally restricts efi_relocate_kernel to cases where we > really need it rather than whenever we were loaded at something other > than preferred address. > > Based on tip:efi/core + the cleanup series [1] > [1] https://lore.kernel.org/linux-efi/20200301230436.2246909-1-nivedita@xxxxxxxxxxxx/ > > Changes from v1 > - clarify a few comments > - cleanups to code formatting > > Arvind Sankar (5): > x86/boot/compressed/32: Save the output address instead of > recalculating it > efi/x86: Decompress at start of PE image load address > efi/x86: Add kernel preferred address to PE header > efi/x86: Remove extra headroom for setup block > efi/x86: Don't relocate the kernel unless necessary > Thanks. I have queued these up in efi/next, along with your mixed mode cleanups. > arch/x86/boot/compressed/head_32.S | 42 +++++++++++++++------- > arch/x86/boot/compressed/head_64.S | 42 ++++++++++++++++++++-- > arch/x86/boot/header.S | 6 ++-- > arch/x86/boot/tools/build.c | 44 ++++++++++++++++------- > drivers/firmware/efi/libstub/x86-stub.c | 48 ++++++++++++++++++++++--- > 5 files changed, 147 insertions(+), 35 deletions(-) > > Range-diff against v1: > 1: 0cdb6bf27a24 ! 1: 2ecbf60b9ecd x86/boot/compressed/32: Save the output address instead of recalculating it > @@ Metadata > ## Commit message ## > x86/boot/compressed/32: Save the output address instead of recalculating it > > - In preparation for being able to decompress starting at a different > - address than startup_32, save the calculated output address instead of > - recalculating it later. > + In preparation for being able to decompress into a buffer starting at a > + different address than startup_32, save the calculated output address > + instead of recalculating it later. > > We now keep track of three addresses: > %edx: startup_32 as we were loaded by bootloader > 2: d4df840752ac ! 2: e2bdbe6cb692 efi/x86: Decompress at start of PE image load address > @@ arch/x86/boot/compressed/head_64.S: SYM_FUNC_START(efi32_pe_entry) > movl -4(%ebp), %esi // loaded_image > movl LI32_image_base(%esi), %esi // loaded_image->image_base > movl %ebx, %ebp // startup_32 for efi32_pe_stub_entry > ++ /* > ++ * We need to set the image_offset variable here since startup_32 will > ++ * use it before we get to the 64-bit efi_pe_entry in C code. > ++ */ > + subl %esi, %ebx > + movl %ebx, image_offset(%ebp) // save image_offset > jmp efi32_pe_stub_entry > @@ drivers/firmware/efi/libstub/x86-stub.c: unsigned long efi_main(efi_handle_t han > efi_printk("efi_relocate_kernel() failed!\n"); > goto fail; > } > ++ /* > ++ * Now that we've copied the kernel elsewhere, we no longer > ++ * have a setup block before startup_32, so reset image_offset > ++ * to zero in case it was set earlier. > ++ */ > + image_offset = 0; > } > > 3: 4bae68f25b90 ! 3: ea840f78f138 efi/x86: Add kernel preferred address to PE header > @@ arch/x86/boot/header.S: optional_header: > > extra_header_fields: > + # PE specification requires ImageBase to be 64k-aligned > -+ .set ImageBase, (LOAD_PHYSICAL_ADDR+0xffff) & ~0xffff > ++ .set image_base, (LOAD_PHYSICAL_ADDR + 0xffff) & ~0xffff > #ifdef CONFIG_X86_32 > - .long 0 # ImageBase > -+ .long ImageBase # ImageBase > ++ .long image_base # ImageBase > #else > - .quad 0 # ImageBase > -+ .quad ImageBase # ImageBase > ++ .quad image_base # ImageBase > #endif > .long 0x20 # SectionAlignment > .long 0x20 # FileAlignment > 4: 2330a25c6b0f ! 4: c25a9b507d6d efi/x86: Remove extra headroom for setup block > @@ Commit message > account for setup block") added headroom to the PE image to account for > the setup block, which wasn't used for the decompression buffer. > > - Now that we decompress from the start of the image, this is no longer > - required. > + Now that the decompression buffer is located at the start of the image, > + and includes the setup block, this is no longer required. > > Add a check to make sure that the head section of the compressed kernel > won't overwrite itself while relocating. This is only for > 5: 2081f91cbe75 ! 5: d3dc3af1c7b8 efi/x86: Don't relocate the kernel unless necessary > @@ arch/x86/boot/tools/build.c: static void update_pecoff_text(unsigned int text_st > * Size of code: Subtract the size of the first sector (512 bytes) > > ## drivers/firmware/efi/libstub/x86-stub.c ## > +@@ > + > + #include "efistub.h" > + > ++/* Maximum physical address for 64-bit kernel with 4-level paging */ > ++#define MAXMEM_X86_64_4LEVEL (1ull << 46) > ++ > + static efi_system_table_t *sys_table; > + extern const bool efi_is64; > + extern u32 image_offset; > @@ drivers/firmware/efi/libstub/x86-stub.c: unsigned long efi_main(efi_handle_t handle, > struct boot_params *boot_params) > { > @@ drivers/firmware/efi/libstub/x86-stub.c: unsigned long efi_main(efi_handle_t han > - * address, relocate it. > + * If the kernel isn't already loaded at a suitable address, > + * relocate it. > ++ * > + * It must be loaded above LOAD_PHYSICAL_ADDR. > -+ * The maximum address for 64-bit is 1 << 46 for 4-level paging. > ++ * > ++ * The maximum address for 64-bit is 1 << 46 for 4-level paging. This > ++ * is defined as the macro MAXMEM, but unfortunately that is not a > ++ * compile-time constant if 5-level paging is configured, so we instead > ++ * define our own macro for use here. > ++ * > + * For 32-bit, the maximum address is complicated to figure out, for > + * now use KERNEL_IMAGE_SIZE, which will be 512MiB, the same as what > + * KASLR uses. > ++ * > + * Also relocate it if image_offset is zero, i.e. we weren't loaded by > + * LoadImage, but we are not aligned correctly. > */ > - if (bzimage_addr - image_offset != hdr->pref_address) { > ++ > + buffer_start = ALIGN(bzimage_addr - image_offset, > + hdr->kernel_alignment); > + buffer_end = buffer_start + hdr->init_size; > + > -+ if (buffer_start < LOAD_PHYSICAL_ADDR > -+ || IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE > -+ || IS_ENABLED(CONFIG_X86_64) && buffer_end > 1ull << 46 > -+ || image_offset == 0 && !IS_ALIGNED(bzimage_addr, > -+ hdr->kernel_alignment)) { > ++ if ((buffer_start < LOAD_PHYSICAL_ADDR) || > ++ (IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE) || > ++ (IS_ENABLED(CONFIG_X86_64) && buffer_end > MAXMEM_X86_64_4LEVEL) || > ++ (image_offset == 0 && !IS_ALIGNED(bzimage_addr, > ++ hdr->kernel_alignment))) { > status = efi_relocate_kernel(&bzimage_addr, > hdr->init_size, hdr->init_size, > hdr->pref_address, > -- > 2.24.1 >
