efi/libstub: Fix boot argument handling in mixed mode entry code (12dc9e15) · Commits · 戴 / test

The mixed mode refactor actually broke mixed mode by failing to pass the bootparam structure to startup_32(). This went unnoticed because it apparently has a high tolerance for being passed random junk, and still boots fine in some cases. So let's fix this by populating %esi as required when entering via efi32_stub_entry, and while at it, preserve the arguments themselves instead of their address in memory (via the stack pointer) since that memory could be clobbered before we get to it. Signed-off-by:

Ard Biesheuvel <ardb@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arvind Sankar <nivedita@alum.mit.edu> Cc: Matthew Garrett <mjg59@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20200103113953.9571-2-ardb@kernel.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/x86/boot/compressed/head_64.S

+10 −7

Original line number	Diff line number	Diff line
		@@ -208,13 +208,12 @@ SYM_FUNC_START(startup_32)
		pushl $__KERNEL_CS
		leal startup_64(%ebp), %eax
		#ifdef CONFIG_EFI_MIXED
		movl efi32_boot_args(%ebp), %ebx
		cmp $0, %ebx
		movl efi32_boot_args(%ebp), %edi
		cmp $0, %edi
		jz 1f
		leal handover_entry(%ebp), %eax
		movl 0(%ebx), %edi
		movl 4(%ebx), %esi
		movl 8(%ebx), %edx
		movl %esi, %edx
		movl efi32_boot_args+4(%ebp), %esi
		movl $0x0, %ecx
		1:
		#endif
		@@ -232,12 +231,16 @@ SYM_FUNC_END(startup_32)
		.org 0x190
		SYM_FUNC_START(efi32_stub_entry)
		add $0x4, %esp /* Discard return address */
		popl %ecx
		popl %edx
		popl %esi

		call 1f
		1: pop %ebp
		subl $1b, %ebp

		movl %esp, efi32_boot_args(%ebp)
		movl %ecx, efi32_boot_args(%ebp)
		movl %edx, efi32_boot_args+4(%ebp)
		sgdtl efi32_boot_gdt(%ebp)

		/* Disable paging */
		@@ -628,7 +631,7 @@ SYM_DATA_START_LOCAL(gdt)
		SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)

		#ifdef CONFIG_EFI_MIXED
		SYM_DATA_LOCAL(efi32_boot_args, .long 0)
		SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0)
		#endif

		/*

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