Commit 44f155b4 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi/libstub: x86/mixed: increase supported argument count 



Increase the number of arguments supported by mixed mode calls, so that
we will be able to call into the TCG2 protocol to measure the initrd
and extend the associated PCR. This involves the TCG2 protocol's
hash_log_extend_event() method, which takes five arguments, three of
which are u64 and need to be split, producing a total of 8 outgoing

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarIlias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://lore.kernel.org/r/20211119114745.1560453-3-ilias.apalodimas@linaro.org


Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 4da87c51

arch/x86/boot/compressed/efi_thunk_64.S

+11 −3
Original line number Diff line number Diff line
@@ -26,8 +26,6 @@ SYM_FUNC_START(__efi64_thunk) 
	push	%rbp

	push	%rbx



	leaq	1f(%rip), %rbp



	movl	%ds, %eax

	push	%rax

	movl	%es, %eax
@@ -35,6 +33,11 @@ SYM_FUNC_START(__efi64_thunk) 
	movl	%ss, %eax

	push	%rax



	/* Copy args passed on stack */

	movq	0x30(%rsp), %rbp

	movq	0x38(%rsp), %rbx

	movq	0x40(%rsp), %rax



	/*

	 * Convert x86-64 ABI params to i386 ABI

	 */
@@ -44,13 +47,18 @@ SYM_FUNC_START(__efi64_thunk) 
	movl	%ecx, 0x8(%rsp)

	movl	%r8d, 0xc(%rsp)

	movl	%r9d, 0x10(%rsp)

	movl	%ebp, 0x14(%rsp)

	movl	%ebx, 0x18(%rsp)

	movl	%eax, 0x1c(%rsp)



	leaq	0x14(%rsp), %rbx

	leaq	0x20(%rsp), %rbx

	sgdt	(%rbx)



	addq	$16, %rbx

	sidt	(%rbx)



	leaq	1f(%rip), %rbp



	/*

	 * Switch to IDT and GDT with 32-bit segments. This is the firmware GDT

	 * and IDT that was installed when the kernel started executing. The

arch/x86/include/asm/efi.h

+6 −4
Original line number Diff line number Diff line
@@ -46,13 +46,14 @@ extern unsigned long efi_mixed_mode_stack_pa; 


#define __efi_nargs(...) __efi_nargs_(__VA_ARGS__)

#define __efi_nargs_(...) __efi_nargs__(0, ##__VA_ARGS__,	\

	__efi_arg_sentinel(9), __efi_arg_sentinel(8),		\

	__efi_arg_sentinel(7), __efi_arg_sentinel(6),		\

	__efi_arg_sentinel(5), __efi_arg_sentinel(4),		\

	__efi_arg_sentinel(3), __efi_arg_sentinel(2),		\

	__efi_arg_sentinel(1), __efi_arg_sentinel(0))

#define __efi_nargs__(_0, _1, _2, _3, _4, _5, _6, _7, n, ...)	\

#define __efi_nargs__(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, n, ...)	\

	__take_second_arg(n,					\

		({ BUILD_BUG_ON_MSG(1, "__efi_nargs limit exceeded"); 8; }))

		({ BUILD_BUG_ON_MSG(1, "__efi_nargs limit exceeded"); 10; }))

#define __efi_arg_sentinel(n) , n



/*
@@ -176,8 +177,9 @@ extern u64 efi_setup; 
extern efi_status_t __efi64_thunk(u32, ...);



#define efi64_thunk(...) ({						\

	__efi_nargs_check(efi64_thunk, 6, __VA_ARGS__);			\

	__efi64_thunk(__VA_ARGS__);					\

	u64 __pad[3]; /* must have space for 3 args on the stack */	\

	__efi_nargs_check(efi64_thunk, 9, __VA_ARGS__);			\

	__efi64_thunk(__VA_ARGS__, __pad);				\

})



static inline bool efi_is_mixed(void)

arch/x86/platform/efi/efi_thunk_64.S

+12 −2
Original line number Diff line number Diff line
@@ -36,6 +36,17 @@ SYM_CODE_START(__efi64_thunk) 
	movq	efi_mixed_mode_stack_pa(%rip), %rsp

	push	%rax



	/*

	 * Copy args passed via the stack

	 */

	subq	$0x24, %rsp

	movq	0x18(%rax), %rbp

	movq	0x20(%rax), %rbx

	movq	0x28(%rax), %rax

	movl	%ebp, 0x18(%rsp)

	movl	%ebx, 0x1c(%rsp)

	movl	%eax, 0x20(%rsp)



	/*

	 * Calculate the physical address of the kernel text.

	 */
@@ -47,7 +58,6 @@ SYM_CODE_START(__efi64_thunk) 
	subq	%rax, %rbp

	subq	%rax, %rbx



	subq	$28, %rsp

	movl	%ebx, 0x0(%rsp)		/* return address */

	movl	%esi, 0x4(%rsp)

	movl	%edx, 0x8(%rsp)
@@ -60,7 +70,7 @@ SYM_CODE_START(__efi64_thunk) 
	pushq	%rdi			/* EFI runtime service address */

	lretq



1:	movq	24(%rsp), %rsp

1:	movq	0x20(%rsp), %rsp

	pop	%rbx

	pop	%rbp

	retq