From efdcb4634a6bea7cf900511f9b962c41d4e04fb0 Mon Sep 17 00:00:00 2001 From: Arthur Heymans Date: Thu, 3 Mar 2022 22:31:56 +0100 Subject: [PATCH] cbfstool/linux_trampoline: Fill the ACPI RSDP entry With LinuxBoot Linux relied on the legacy method of fetching the RSDP pointer to get ACPI. This uses a more modern approach available since 2018 on the Linux kernel, which involves filling in the zero page. This method takes precedence over any other method of fetching the RSDP in Linux (UEFI, Kexec, Legacy/BIOS). Some UEFI zealots are threatening that legacy code will be removed from Linux so it's best to already adapt to that possibility. Tested on Qemu: - With qemu the RSDP is always in the EBDA, so checking if Linux uses the provided pointer is better done with a forced bad entry - With a fake bad pointer Linux correctly does not find RDSP Change-Id: I688b94608b03b0177c42d2834c7e3beb802ae686 Signed-off-by: Arthur Heymans Reviewed-on: https://review.coreboot.org/c/coreboot/+/62574 Tested-by: build bot (Jenkins) Reviewed-by: Tim Wawrzynczak Reviewed-by: Nico Huber Reviewed-by: Angel Pons --- util/cbfstool/linux_trampoline.S | 14 +++++++++++++- util/cbfstool/linux_trampoline.c | 17 +++++++++-------- 2 files changed, 22 insertions(+), 9 deletions(-) diff --git a/util/cbfstool/linux_trampoline.S b/util/cbfstool/linux_trampoline.S index 726852804f..767c8bebd3 100644 --- a/util/cbfstool/linux_trampoline.S +++ b/util/cbfstool/linux_trampoline.S @@ -13,7 +13,9 @@ #define CB_TAG_FORWARD 0x11 #define CB_TAG_MEMORY 0x1 #define CB_TAG_FRAMEBUFFER 0x12 +#define CB_TAG_ACPI_RSDP 0x43 +#define ACPI_RSDP_ADDR 0x70 #define E820_NR_OFFSET 0x1e8 #define LINUX_ENTRY_OFFSET 0x214 #define E820_OFFSET 0x2d0 @@ -52,7 +54,7 @@ jmp .headerSearch .testMemory: cmp $CB_TAG_MEMORY, (%ebx) -jne .testFramebuffer +jne .testAcpiRsdp /* memory tag: copy e820 map and entry count. also determine alt_mem_k */ mov 4(%ebx), %eax @@ -87,6 +89,16 @@ dec %eax add $20, %edi jmp .test_e820_entry +.testAcpiRsdp: +cmp $CB_TAG_ACPI_RSDP, (%ebx) +jne .testFramebuffer + +mov 8(%ebx), %eax +mov %eax, (LINUX_PARAM_LOC + ACPI_RSDP_ADDR) +mov 12(%ebx), %eax +mov %eax, (LINUX_PARAM_LOC + ACPI_RSDP_ADDR + 4) +jmp .endScan + .testFramebuffer: cmp $CB_TAG_FRAMEBUFFER, (%ebx) jne .endScan diff --git a/util/cbfstool/linux_trampoline.c b/util/cbfstool/linux_trampoline.c index b804c80542..46bb800ad6 100644 --- a/util/cbfstool/linux_trampoline.c +++ b/util/cbfstool/linux_trampoline.c @@ -3,17 +3,18 @@ unsigned char trampoline[] = { 0xfc, 0x31, 0xd2, 0xb9, 0x00, 0x00, 0x00, 0x00, 0xbb, 0x00, 0x00, 0x01, 0x00, 0x01, 0xcb, 0x8b, 0x01, 0x3d, 0x4c, 0x42, 0x49, 0x4f, 0x74, 0x07, 0x83, 0xc1, 0x10, 0x39, 0xcb, 0x75, 0xe9, 0x39, - 0xcb, 0x0f, 0x84, 0xaa, 0x00, 0x00, 0x00, 0x8b, 0x59, 0x04, 0x01, 0xcb, 0x8b, 0x49, 0x14, 0x83, + 0xcb, 0x0f, 0x84, 0xc5, 0x00, 0x00, 0x00, 0x8b, 0x59, 0x04, 0x01, 0xcb, 0x8b, 0x49, 0x14, 0x83, 0x3b, 0x11, 0x75, 0x05, 0x8b, 0x4b, 0x08, 0xeb, 0xcf, 0x83, 0x3b, 0x01, 0x75, 0x53, 0x8b, 0x43, 0x04, 0x83, 0xe8, 0x08, 0xc1, 0xe8, 0x02, 0x3d, 0xa0, 0x00, 0x00, 0x00, 0x7e, 0x05, 0xb8, 0xa0, 0x00, 0x00, 0x00, 0x89, 0xc6, 0xbf, 0x05, 0x00, 0x00, 0x00, 0xf7, 0xf7, 0xa3, 0xe8, 0x01, 0x09, 0x00, 0x89, 0xf0, 0x91, 0x8d, 0x73, 0x08, 0xbf, 0xd0, 0x02, 0x09, 0x00, 0xf3, 0xa5, 0x91, 0xa1, - 0xe8, 0x01, 0x09, 0x00, 0xbf, 0xd0, 0x02, 0x09, 0x00, 0x83, 0xf8, 0x00, 0x74, 0x18, 0x83, 0x7f, + 0xe8, 0x01, 0x09, 0x00, 0xbf, 0xd0, 0x02, 0x09, 0x00, 0x83, 0xf8, 0x00, 0x74, 0x2f, 0x83, 0x7f, 0x10, 0x0c, 0x7e, 0x07, 0xc7, 0x47, 0x10, 0x02, 0x00, 0x00, 0x00, 0x48, 0x83, 0xc7, 0x14, 0xeb, - 0xe8, 0x83, 0x3b, 0x12, 0x75, 0x00, 0x03, 0x5b, 0x04, 0x49, 0x75, 0x93, 0xb8, 0x00, 0x00, 0x04, - 0x00, 0xc7, 0x40, 0x10, 0xff, 0xff, 0x00, 0x00, 0xc7, 0x40, 0x14, 0x00, 0x9b, 0xcf, 0x00, 0xc7, - 0x40, 0x18, 0xff, 0xff, 0x00, 0x00, 0xc7, 0x40, 0x1c, 0x00, 0x93, 0xcf, 0x00, 0xc6, 0x00, 0x2b, - 0x89, 0x40, 0x02, 0x0f, 0x01, 0x10, 0xbe, 0x00, 0x00, 0x09, 0x00, 0xff, 0x25, 0x14, 0x02, 0x09, - 0x00, 0xf4, 0xeb, 0xfd + 0xe8, 0x83, 0x3b, 0x43, 0x75, 0x12, 0x8b, 0x43, 0x08, 0xa3, 0x70, 0x00, 0x09, 0x00, 0x8b, 0x43, + 0x0c, 0xa3, 0x74, 0x00, 0x09, 0x00, 0xeb, 0x05, 0x83, 0x3b, 0x12, 0x75, 0x00, 0x03, 0x5b, 0x04, + 0x49, 0x0f, 0x85, 0x78, 0xff, 0xff, 0xff, 0xb8, 0x00, 0x00, 0x04, 0x00, 0xc7, 0x40, 0x10, 0xff, + 0xff, 0x00, 0x00, 0xc7, 0x40, 0x14, 0x00, 0x9b, 0xcf, 0x00, 0xc7, 0x40, 0x18, 0xff, 0xff, 0x00, + 0x00, 0xc7, 0x40, 0x1c, 0x00, 0x93, 0xcf, 0x00, 0xc6, 0x00, 0x2b, 0x89, 0x40, 0x02, 0x0f, 0x01, + 0x10, 0xbe, 0x00, 0x00, 0x09, 0x00, 0xff, 0x25, 0x14, 0x02, 0x09, 0x00, 0xf4, 0xeb, 0xfd }; -unsigned int trampoline_len = 212; +unsigned int trampoline_len = 239;