Re: [PATCH] x86/boot: Add an efi.h header for the decompressor

From: Ard Biesheuvel
Date: Wed Apr 13 2022 - 13:35:26 EST

On Fri, 8 Apr 2022 at 21:17, Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> Hi,
>
> this is something that has been bothering me for a while: kernel proper
> namespace leaking into the decompressor and causing all kinds of ugly
> conflicts between definitions and us having to do preprocessor hacks to
> fix the build.
>
> We recently started putting shared functionality into
>
> arch/x86/include/asm/shared/
>
> The other thing to do is to copy linux/ namespace symbols into a
> separate decompressor header and then block any further includes of
> headers from there. Future needs would simply copy the required bits
> like I did below.
>
> And this below is converting the efi side of things. It goes ontop of
> the x86/sev branch which adds two more linux/efi.h includes and which
> triggered me to finally productize this.
>
> I'll queue it soon if there are no objections.
>

No objection from me.



> ---
> From: Borislav Petkov <bp@xxxxxxx>
>
> Copy the needed symbols only and remove the kernel proper includes.
>
> No functional changes.
>
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> ---
> arch/x86/boot/compressed/acpi.c | 3 +-
> arch/x86/boot/compressed/efi.c | 2 -
> arch/x86/boot/compressed/efi.h | 126 ++++++++++++++++++++++++++
> arch/x86/boot/compressed/kaslr.c | 3 +-
> arch/x86/boot/compressed/misc.h | 3 +-
> arch/x86/boot/compressed/pgtable_64.c | 3 +-
> 6 files changed, 131 insertions(+), 9 deletions(-)
> create mode 100644 arch/x86/boot/compressed/efi.h
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index 64b172dabd5c..9caf89063e77 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -3,10 +3,9 @@
> #include "misc.h"
> #include "error.h"
> #include "../string.h"
> +#include "efi.h"
>
> #include <linux/numa.h>
> -#include <linux/efi.h>
> -#include <asm/efi.h>
>
> /*
> * Longest parameter of 'acpi=' is 'copy_dsdt', plus an extra '\0'
> diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
> index 09fa3b5d70b8..6edd034b0b30 100644
> --- a/arch/x86/boot/compressed/efi.c
> +++ b/arch/x86/boot/compressed/efi.c
> @@ -6,8 +6,6 @@
> */
>
> #include "misc.h"
> -#include <linux/efi.h>
> -#include <asm/efi.h>
>
> /**
> * efi_get_type - Given a pointer to boot_params, determine the type of EFI environment.
> diff --git a/arch/x86/boot/compressed/efi.h b/arch/x86/boot/compressed/efi.h
> new file mode 100644
> index 000000000000..7db2f41b54cd
> --- /dev/null
> +++ b/arch/x86/boot/compressed/efi.h
> @@ -0,0 +1,126 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef BOOT_COMPRESSED_EFI_H
> +#define BOOT_COMPRESSED_EFI_H
> +
> +#if defined(_LINUX_EFI_H) || defined(_ASM_X86_EFI_H)
> +#error Please do not include kernel proper namespace headers
> +#endif
> +
> +typedef guid_t efi_guid_t __aligned(__alignof__(u32));
> +
> +#define EFI_GUID(a, b, c, d...) (efi_guid_t){ { \
> + (a) & 0xff, ((a) >> 8) & 0xff, ((a) >> 16) & 0xff, ((a) >> 24) & 0xff, \
> + (b) & 0xff, ((b) >> 8) & 0xff, \
> + (c) & 0xff, ((c) >> 8) & 0xff, d } }
> +
> +#define ACPI_TABLE_GUID EFI_GUID(0xeb9d2d30, 0x2d88, 0x11d3, 0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
> +#define ACPI_20_TABLE_GUID EFI_GUID(0x8868e871, 0xe4f1, 0x11d3, 0xbc, 0x22, 0x00, 0x80, 0xc7, 0x3c, 0x88, 0x81)
> +#define EFI_CC_BLOB_GUID EFI_GUID(0x067b1f5f, 0xcf26, 0x44c5, 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42)
> +
> +#define EFI32_LOADER_SIGNATURE "EL32"
> +#define EFI64_LOADER_SIGNATURE "EL64"
> +
> +/*
> + * Generic EFI table header
> + */
> +typedef struct {
> + u64 signature;
> + u32 revision;
> + u32 headersize;
> + u32 crc32;
> + u32 reserved;
> +} efi_table_hdr_t;
> +
> +#define EFI_CONVENTIONAL_MEMORY 7
> +
> +#define EFI_MEMORY_MORE_RELIABLE \
> + ((u64)0x0000000000010000ULL) /* higher reliability */
> +#define EFI_MEMORY_SP ((u64)0x0000000000040000ULL) /* soft reserved */
> +
> +#define EFI_PAGE_SHIFT 12
> +
> +typedef struct {
> + u32 type;
> + u32 pad;
> + u64 phys_addr;
> + u64 virt_addr;
> + u64 num_pages;
> + u64 attribute;
> +} efi_memory_desc_t;
> +
> +#define efi_early_memdesc_ptr(map, desc_size, n) \
> + (efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size)))
> +
> +typedef struct {
> + efi_guid_t guid;
> + u64 table;
> +} efi_config_table_64_t;
> +
> +typedef struct {
> + efi_guid_t guid;
> + u32 table;
> +} efi_config_table_32_t;
> +
> +typedef struct {
> + efi_table_hdr_t hdr;
> + u64 fw_vendor; /* physical addr of CHAR16 vendor string */
> + u32 fw_revision;
> + u32 __pad1;
> + u64 con_in_handle;
> + u64 con_in;
> + u64 con_out_handle;
> + u64 con_out;
> + u64 stderr_handle;
> + u64 stderr;
> + u64 runtime;
> + u64 boottime;
> + u32 nr_tables;
> + u32 __pad2;
> + u64 tables;
> +} efi_system_table_64_t;
> +
> +typedef struct {
> + efi_table_hdr_t hdr;
> + u32 fw_vendor; /* physical addr of CHAR16 vendor string */
> + u32 fw_revision;
> + u32 con_in_handle;
> + u32 con_in;
> + u32 con_out_handle;
> + u32 con_out;
> + u32 stderr_handle;
> + u32 stderr;
> + u32 runtime;
> + u32 boottime;
> + u32 nr_tables;
> + u32 tables;
> +} efi_system_table_32_t;
> +
> +/* kexec external ABI */
> +struct efi_setup_data {
> + u64 fw_vendor;
> + u64 __unused;
> + u64 tables;
> + u64 smbios;
> + u64 reserved[8];
> +};
> +
> +static inline int efi_guidcmp (efi_guid_t left, efi_guid_t right)
> +{
> + return memcmp(&left, &right, sizeof (efi_guid_t));
> +}
> +
> +#ifdef CONFIG_EFI
> +bool __pure __efi_soft_reserve_enabled(void);
> +
> +static inline bool __pure efi_soft_reserve_enabled(void)
> +{
> + return IS_ENABLED(CONFIG_EFI_SOFT_RESERVE)
> + && __efi_soft_reserve_enabled();
> +}
> +#else
> +static inline bool efi_soft_reserve_enabled(void)
> +{
> + return false;
> +}
> +#endif /* CONFIG_EFI */
> +#endif /* BOOT_COMPRESSED_EFI_H */
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 411b268bc0a2..4a3f223973f4 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -22,15 +22,14 @@
> #include "misc.h"
> #include "error.h"
> #include "../string.h"
> +#include "efi.h"
>
> #include <generated/compile.h>
> #include <linux/module.h>
> #include <linux/uts.h>
> #include <linux/utsname.h>
> #include <linux/ctype.h>
> -#include <linux/efi.h>
> #include <generated/utsrelease.h>
> -#include <asm/efi.h>
>
> #define _SETUP
> #include <asm/setup.h> /* For COMMAND_LINE_SIZE */
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index 75d284ec763f..4ca2857ea041 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -23,7 +23,6 @@
> #include <linux/screen_info.h>
> #include <linux/elf.h>
> #include <linux/io.h>
> -#include <linux/efi.h>
> #include <asm/page.h>
> #include <asm/boot.h>
> #include <asm/bootparam.h>
> @@ -35,6 +34,8 @@
> #define BOOT_BOOT_H
> #include "../ctype.h"
>
> +#include "efi.h"
> +
> #ifdef CONFIG_X86_64
> #define memptr long
> #else
> diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
> index a1733319a22a..2ac12ff4111b 100644
> --- a/arch/x86/boot/compressed/pgtable_64.c
> +++ b/arch/x86/boot/compressed/pgtable_64.c
> @@ -1,11 +1,10 @@
> // SPDX-License-Identifier: GPL-2.0
> #include "misc.h"
> -#include <linux/efi.h>
> #include <asm/e820/types.h>
> #include <asm/processor.h>
> -#include <asm/efi.h>
> #include "pgtable.h"
> #include "../string.h"
> +#include "efi.h"
>
> #define BIOS_START_MIN 0x20000U /* 128K, less than this is insane */
> #define BIOS_START_MAX 0x9f000U /* 640K, absolute maximum */
> --
> 2.35.1
>
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette