lwn.git/arch/x86/boot/compressed/eboot.c, branch docs-next

efi/libstub/x86: Incorporate eboot.c into libstub

2020-02-23T20:57:15+00:00

Most of the EFI stub source files of all architectures reside under drivers/firmware/efi/libstub, where they share a Makefile with special CFLAGS and an include file with declarations that are only relevant for stub code. Currently, we carry a lot of stub specific stuff in linux/efi.h only because eboot.c in arch/x86 needs them as well. So let's move eboot.c into libstub/, and move the contents of eboot.h that we still care about into efistub.h Signed-off-by: Ard Biesheuvel

efi/libstub/x86: Avoid overflowing code32_start on PE entry

2020-02-22T22:37:37+00:00

When using the native PE entry point (as opposed to the EFI handover protocol entry point that is used more widely), we set code32_start, which is a 32-bit wide field, to the effective symbol address of startup_32, which could overflow given that the EFI loader may have located the running image anywhere in memory, and we haven't reached the point yet where we relocate ourselves. Since we relocate ourselves if code32_start != pref_address, this isn't likely to lead to problems in practice, given how unlikely it is that the truncated effective address of startup_32 happens to equal pref_address. But it is better to defer the assignment of code32_start to after the relocation, when it is guaranteed to fit. While at it, move the call to efi_relocate_kernel() to an earlier stage so it is more likely that our preferred offset in memory has not been occupied by other memory allocations done in the mean time. Signed-off-by: Ard Biesheuvel

efi/libstub/x86: Remove pointless zeroing of apm_bios_info

2020-02-22T22:37:37+00:00

We have some code in the EFI stub entry point that takes the address of the apm_bios_info struct in the newly allocated and zeroed out boot_params structure, only to zero it out again. This is pointless so remove it. Signed-off-by: Ard Biesheuvel

efi/x86: Mark setup_graphics static

2020-02-22T22:37:37+00:00

This function is only called from efi_main in the same source file. Signed-off-by: Arvind Sankar Link: https://lore.kernel.org/r/20200130222004.1932152-1-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel

efi/x86: Remove GDT setup from efi_main

2020-02-22T22:37:37+00:00

The 64-bit kernel will already load a GDT in startup_64, which is the next function to execute after return from efi_main. Add GDT setup code to the 32-bit kernel's startup_32 as well. Doing it in the head code has the advantage that we can avoid potentially corrupting the GDT during copy/decompression. This also removes dependence on having a specific GDT layout setup by the bootloader. Both startup_32 and startup_64 now clear interrupts on entry, so we can remove that from efi_main as well. Signed-off-by: Arvind Sankar Link: https://lore.kernel.org/r/20200202171353.3736319-6-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel

efi/libstub/x86: Fix EFI server boot failure

2020-01-25T09:14:36+00:00

x86_64 EFI systems are unable to boot due to a typo in a recent commit: EFI config tables not found. -- System halted This was probably due to the absense of CONFIG_EFI_MIXED=y in testing. Fixes: 796eb8d26a57 ("efi/libstub/x86: Use const attribute for efi_is_64bit()") Signed-off-by: Qian Cai Acked-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: tglx@linutronix.de Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20200122191430.4888-1-cai@lca.pw

efi/libstub/x86: Fix unused-variable warning

2020-01-20T07:13:00+00:00

The only users of these got removed, so they also need to be removed to avoid warnings: arch/x86/boot/compressed/eboot.c: In function 'setup_efi_pci': arch/x86/boot/compressed/eboot.c:117:16: error: unused variable 'nr_pci' [-Werror=unused-variable] unsigned long nr_pci; ^~~~~~ arch/x86/boot/compressed/eboot.c: In function 'setup_uga': arch/x86/boot/compressed/eboot.c:244:16: error: unused variable 'nr_ugas' [-Werror=unused-variable] unsigned long nr_ugas; ^~~~~~~ Fixes: 2732ea0d5c0a ("efi/libstub: Use a helper to iterate over a EFI handle array") Signed-off-by: Arnd Bergmann Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200113172245.27925-4-ardb@kernel.org

efi/libstub/x86: Use const attribute for efi_is_64bit()

2020-01-20T07:13:00+00:00

Reshuffle the x86 stub code a bit so that we can tag the efi_is_64bit() function with the 'const' attribute, which permits the compiler to optimize away any redundant calls. Since we have two different entry points for 32 and 64 bit firmware in the startup code, this also simplifies the C code since we'll enter it with the efi_is64 variable already set. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200113172245.27925-2-ardb@kernel.org

efi/x86: Allow translating 64-bit arguments for mixed mode calls

2020-01-10T17:55:04+00:00

Introduce the ability to define macros to perform argument translation for the calls that need it, and define them for the boot services that we currently use. When calling 32-bit firmware methods in mixed mode, all output parameters that are 32-bit according to the firmware, but 64-bit in the kernel (ie OUT UINTN * or OUT VOID **) must be initialized in the kernel, or the upper 32 bits may contain garbage. Define macros that zero out the upper 32 bits of the output before invoking the firmware method. When a 32-bit EFI call takes 64-bit arguments, the mixed-mode call must push the two 32-bit halves as separate arguments onto the stack. This can be achieved by splitting the argument into its two halves when calling the assembler thunk. Define a macro to do this for the free_pages boot service. Signed-off-by: Arvind Sankar Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Matthew Garrett Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20200103113953.9571-17-ardb@kernel.org Signed-off-by: Ingo Molnar

efi/libstub/x86: Force 'hidden' visibility for extern declarations

2020-01-10T17:55:01+00:00

Commit c3710de5065d ("efi/libstub/x86: Drop __efi_early() export and efi_config struct") introduced a reference from C code in eboot.c to the startup_32 symbol defined in the .S startup code. This results in a GOT based reference to startup_32, and since GOT entries carry absolute addresses, they need to be fixed up before they can be used. On modern toolchains (binutils 2.26 or later), this reference is relaxed into a R_386_GOTOFF relocation (or the analogous X86_64 one) which never uses the absolute address in the entry, and so we get away with not fixing up the GOT table before calling the EFI entry point. However, GCC 4.6 combined with a binutils of the era (2.24) will produce a true GOT indirected reference, resulting in a wrong value to be returned for the address of startup_32() if the boot code is not running at the address it was linked at. Fortunately, we can easily override this behavior, and force GCC to emit the GOTOFF relocations explicitly, by setting the visibility pragma 'hidden'. Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arvind Sankar Cc: Matthew Garrett Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20200103113953.9571-3-ardb@kernel.org Signed-off-by: Ingo Molnar