Merge tag 'efi-next-for-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:
 "A bit more going on than usual in the EFI subsystem. The main driver
  for this has been the introduction of the LoonArch architecture last
  cycle, which inspired some cleanup and refactoring of the EFI code.
  Another driver for EFI changes this cycle and in the future is
  confidential compute.

  The LoongArch architecture does not use either struct bootparams or DT
  natively [yet], and so passing information between the EFI stub and
  the core kernel using either of those is undesirable. And in general,
  overloading DT has been a source of issues on arm64, so using DT for
  this on new architectures is a to avoid for the time being (even if we
  might converge on something DT based for non-x86 architectures in the
  future). For this reason, in addition to the patch that enables EFI
  boot for LoongArch, there are a number of refactoring patches applied
  on top of which separate the DT bits from the generic EFI stub bits.
  These changes are on a separate topich branch that has been shared
  with the LoongArch maintainers, who will include it in their pull
  request as well. This is not ideal, but the best way to manage the
  conflicts without stalling LoongArch for another cycle.

  Another development inspired by LoongArch is the newly added support
  for EFI based decompressors. Instead of adding yet another
  arch-specific incarnation of this pattern for LoongArch, we are
  introducing an EFI app based on the existing EFI libstub
  infrastructure that encapulates the decompression code we use on other
  architectures, but in a way that is fully generic. This has been
  developed and tested in collaboration with distro and systemd folks,
  who are eager to start using this for systemd-boot and also for arm64
  secure boot on Fedora. Note that the EFI zimage files this introduces
  can also be decompressed by non-EFI bootloaders if needed, as the
  image header describes the location of the payload inside the image,
  and the type of compression that was used. (Note that Fedora's arm64
  GRUB is buggy [0] so you'll need a recent version or switch to
  systemd-boot in order to use this.)

  Finally, we are adding TPM measurement of the kernel command line
  provided by EFI. There is an oversight in the TCG spec which results
  in a blind spot for command line arguments passed to loaded images,
  which means that either the loader or the stub needs to take the
  measurement. Given the combinatorial explosion I am anticipating when
  it comes to firmware/bootloader stacks and firmware based attestation
  protocols (SEV-SNP, TDX, DICE, DRTM), it is good to set a baseline now
  when it comes to EFI measured boot, which is that the kernel measures
  the initrd and command line. Intermediate loaders can measure
  additional assets if needed, but with the baseline in place, we can
  deploy measured boot in a meaningful way even if you boot into Linux
  straight from the EFI firmware.

  Summary:

   - implement EFI boot support for LoongArch

   - implement generic EFI compressed boot support for arm64, RISC-V and
     LoongArch, none of which implement a decompressor today

   - measure the kernel command line into the TPM if measured boot is in
     effect

   - refactor the EFI stub code in order to isolate DT dependencies for
     architectures other than x86

   - avoid calling SetVirtualAddressMap() on arm64 if the configured
     size of the VA space guarantees that doing so is unnecessary

   - move some ARM specific code out of the generic EFI source files

   - unmap kernel code from the x86 mixed mode 1:1 page tables"

* tag 'efi-next-for-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: (24 commits)
  efi/arm64: libstub: avoid SetVirtualAddressMap() when possible
  efi: zboot: create MemoryMapped() device path for the parent if needed
  efi: libstub: fix up the last remaining open coded boot service call
  efi/arm: libstub: move ARM specific code out of generic routines
  efi/libstub: measure EFI LoadOptions
  efi/libstub: refactor the initrd measuring functions
  efi/loongarch: libstub: remove dependency on flattened DT
  efi: libstub: install boot-time memory map as config table
  efi: libstub: remove DT dependency from generic stub
  efi: libstub: unify initrd loading between architectures
  efi: libstub: remove pointless goto kludge
  efi: libstub: simplify efi_get_memory_map() and struct efi_boot_memmap
  efi: libstub: avoid efi_get_memory_map() for allocating the virt map
  efi: libstub: drop pointless get_memory_map() call
  efi: libstub: fix type confusion for load_options_size
  arm64: efi: enable generic EFI compressed boot
  loongarch: efi: enable generic EFI compressed boot
  riscv: efi: enable generic EFI compressed boot
  efi/libstub: implement generic EFI zboot
  efi/libstub: move efi_system_table global var into separate object
  ...

2 files changed, 23 insertions, 8 deletions

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 1f3675453a57..b36596bf0fc3 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -176,7 +176,8 @@ virt_to_phys_or_null_size(void *va, unsigned long size)
 
 int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 {
-	unsigned long pfn, text, pf, rodata;
+	extern const u8 __efi64_thunk_ret_tramp[];
+	unsigned long pfn, text, pf, rodata, tramp;
 	struct page *page;
 	unsigned npages;
 	pgd_t *pgd = efi_mm.pgd;
@@ -238,11 +239,9 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 
 	npages = (_etext - _text) >> PAGE_SHIFT;
 	text = __pa(_text);
-	pfn = text >> PAGE_SHIFT;
 
-	pf = _PAGE_ENC;
-	if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, pf)) {
-		pr_err("Failed to map kernel text 1:1\n");
+	if (kernel_unmap_pages_in_pgd(pgd, text, npages)) {
+		pr_err("Failed to unmap kernel text 1:1 mapping\n");
 		return 1;
 	}
 
@@ -256,6 +255,15 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 		return 1;
 	}
 
+	tramp = __pa(__efi64_thunk_ret_tramp);
+	pfn = tramp >> PAGE_SHIFT;
+
+	pf = _PAGE_ENC;
+	if (kernel_map_pages_in_pgd(pgd, pfn, tramp, 1, pf)) {
+		pr_err("Failed to map mixed mode return trampoline\n");
+		return 1;
+	}
+
 	return 0;
 }
 
diff --git a/arch/x86/platform/efi/efi_thunk_64.S b/arch/x86/platform/efi/efi_thunk_64.S
index 4e5257a4811b..c4b1144f99f6 100644
--- a/arch/x86/platform/efi/efi_thunk_64.S
+++ b/arch/x86/platform/efi/efi_thunk_64.S
@@ -23,7 +23,6 @@
 #include <linux/objtool.h>
 #include <asm/page_types.h>
 #include <asm/segment.h>
-#include <asm/nospec-branch.h>
 
 	.text
 	.code64
@@ -73,10 +72,18 @@ STACK_FRAME_NON_STANDARD __efi64_thunk
 	pushq	%rdi			/* EFI runtime service address */
 	lretq
 
+	// This return instruction is not needed for correctness, as it will
+	// never be reached. It only exists to make objtool happy, which will
+	// otherwise complain about unreachable instructions in the callers.
+	RET
+SYM_FUNC_END(__efi64_thunk)
+
+	.section ".rodata", "a", @progbits
+	.balign	16
+SYM_DATA_START(__efi64_thunk_ret_tramp)
 1:	movq	0x20(%rsp), %rsp
 	pop	%rbx
 	pop	%rbp
-	ANNOTATE_UNRET_SAFE
 	ret
 	int3
 
@@ -84,7 +91,7 @@ STACK_FRAME_NON_STANDARD __efi64_thunk
 2:	pushl	$__KERNEL_CS
 	pushl	%ebp
 	lret
-SYM_FUNC_END(__efi64_thunk)
+SYM_DATA_END(__efi64_thunk_ret_tramp)
 
 	.bss
 	.balign 8