From 7734a0f31e99c433df3063bbb7e8ee5a16a2cb82 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Mon, 9 Jan 2023 18:04:02 +0100 Subject: x86/boot: Robustify calling startup_{32,64}() from the decompressor code After commit ce697ccee1a8 ("kbuild: remove head-y syntax"), I started digging whether x86 is ready for removing this old cruft. Removing its objects from the list makes the kernel unbootable. This applies only to bzImage, vmlinux still works correctly. The reason is that with no strict object order determined by the linker arguments, not the linker script, startup_64 can be placed not right at the beginning of the kernel. Here's vmlinux.map's beginning before removing: ffffffff81000000 vmlinux.o:(.head.text) ffffffff81000000 startup_64 ffffffff81000070 secondary_startup_64 ffffffff81000075 secondary_startup_64_no_verify ffffffff81000160 verify_cpu and after: ffffffff81000000 vmlinux.o:(.head.text) ffffffff81000000 pvh_start_xen ffffffff81000080 startup_64 ffffffff810000f0 secondary_startup_64 ffffffff810000f5 secondary_startup_64_no_verify Not a problem itself, but the self-extractor code has the address of that function hardcoded the beginning, not looking onto the ELF header, which always contains the address of startup_{32,64}(). So, instead of doing an "act of blind faith", just take the address from the ELF header and extract a relative offset to the entry point. The decompressor function already returns a pointer to the beginning of the kernel to the Asm code, which then jumps to it, so add that offset to the return value. This doesn't change anything for now, but allows to resign from the "head object list" for x86 and makes sure valid Kbuild or any other improvements won't break anything here in general. Signed-off-by: Alexander Lobakin Signed-off-by: Ingo Molnar Tested-by: Jiri Slaby Cc: "H. Peter Anvin" Cc: Linus Torvalds Link: https://lore.kernel.org/r/20230109170403.4117105-2-alexandr.lobakin@intel.com --- arch/x86/boot/compressed/head_32.S | 2 +- arch/x86/boot/compressed/head_64.S | 2 +- arch/x86/boot/compressed/misc.c | 18 +++++++++++------- 3 files changed, 13 insertions(+), 9 deletions(-) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 6589ddd4cfaf..987ae727cf9f 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -187,7 +187,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) leal boot_heap@GOTOFF(%ebx), %eax pushl %eax /* heap area */ pushl %esi /* real mode pointer */ - call extract_kernel /* returns kernel location in %eax */ + call extract_kernel /* returns kernel entry point in %eax */ addl $24, %esp /* diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index a75712991df3..03c4328a88cb 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -569,7 +569,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) movl input_len(%rip), %ecx /* input_len */ movq %rbp, %r8 /* output target address */ movl output_len(%rip), %r9d /* decompressed length, end of relocs */ - call extract_kernel /* returns kernel location in %rax */ + call extract_kernel /* returns kernel entry point in %rax */ popq %rsi /* diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index cf690d8712f4..014ff222bf4b 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -277,7 +277,7 @@ static inline void handle_relocations(void *output, unsigned long output_len, { } #endif -static void parse_elf(void *output) +static size_t parse_elf(void *output) { #ifdef CONFIG_X86_64 Elf64_Ehdr ehdr; @@ -293,10 +293,8 @@ static void parse_elf(void *output) if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || ehdr.e_ident[EI_MAG1] != ELFMAG1 || ehdr.e_ident[EI_MAG2] != ELFMAG2 || - ehdr.e_ident[EI_MAG3] != ELFMAG3) { + ehdr.e_ident[EI_MAG3] != ELFMAG3) error("Kernel is not a valid ELF file"); - return; - } debug_putstr("Parsing ELF... "); @@ -328,6 +326,8 @@ static void parse_elf(void *output) } free(phdrs); + + return ehdr.e_entry - LOAD_PHYSICAL_ADDR; } /* @@ -356,6 +356,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, const unsigned long kernel_total_size = VO__end - VO__text; unsigned long virt_addr = LOAD_PHYSICAL_ADDR; unsigned long needed_size; + size_t entry_offset; /* Retain x86 boot parameters pointer passed from startup_32/64. */ boot_params = rmode; @@ -456,14 +457,17 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, debug_putstr("\nDecompressing Linux... "); __decompress(input_data, input_len, NULL, NULL, output, output_len, NULL, error); - parse_elf(output); + entry_offset = parse_elf(output); handle_relocations(output, output_len, virt_addr); - debug_putstr("done.\nBooting the kernel.\n"); + + debug_putstr("done.\nBooting the kernel (entry_offset: 0x"); + debug_puthex(entry_offset); + debug_putstr(").\n"); /* Disable exception handling before booting the kernel */ cleanup_exception_handling(); - return output; + return output + entry_offset; } void fortify_panic(const char *name) -- cgit v1.2.3 From 5353fff29e42d0efc844dcaf764336d20a7f6b44 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Mon, 9 Jan 2023 18:04:03 +0100 Subject: scripts/head-object-list: Remove x86 from the list Now that x86 boot code is not hardcoded to the particular linking order, remove x86 files from the list and let them be placed inside the vmlinux according only to the linker script and linker preferences. Signed-off-by: Alexander Lobakin Signed-off-by: Ingo Molnar Tested-by: Jiri Slaby Link: https://lore.kernel.org/r/20230109170403.4117105-3-alexandr.lobakin@intel.com --- scripts/head-object-list.txt | 6 ------ 1 file changed, 6 deletions(-) diff --git a/scripts/head-object-list.txt b/scripts/head-object-list.txt index b074134cfac2..b2a0e21ea8d7 100644 --- a/scripts/head-object-list.txt +++ b/scripts/head-object-list.txt @@ -42,10 +42,4 @@ arch/s390/kernel/head64.o arch/sh/kernel/head_32.o arch/sparc/kernel/head_32.o arch/sparc/kernel/head_64.o -arch/x86/kernel/head_32.o -arch/x86/kernel/head_64.o -arch/x86/kernel/head32.o -arch/x86/kernel/head64.o -arch/x86/kernel/ebda.o -arch/x86/kernel/platform-quirks.o arch/xtensa/kernel/head.o -- cgit v1.2.3 From e2869bd7af608c343988429ceb1c2fe99644a01f Mon Sep 17 00:00:00 2001 From: Kishon Vijay Abraham I Date: Thu, 5 Jan 2023 04:10:59 +0000 Subject: x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC Section 5.2.12.12 Processor Local x2APIC Structure in the ACPI v6.5 spec mandates that both "enabled" and "online capable" Local APIC Flags should be used to determine if the processor is usable or not. However, Linux doesn't use the "online capable" flag for x2APIC to determine if the processor is usable. As a result, cpu_possible_mask has incorrect value and results in more memory getting allocated for per_cpu variables than it is going to be used. Make sure Linux parses both "enabled" and "online capable" flags for x2APIC to correctly determine if the processor is usable. Fixes: aa06e20f1be6 ("x86/ACPI: Don't add CPUs that are not online capable") Reported-by: Leo Duran Signed-off-by: Kishon Vijay Abraham I Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Borislav Petkov (AMD) Reviewed-by: Zhang Rui Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20230105041059.39366-1-kvijayab@amd.com --- arch/x86/kernel/acpi/boot.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 907cc98b1938..518bda50068c 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -188,6 +188,17 @@ static int acpi_register_lapic(int id, u32 acpiid, u8 enabled) return cpu; } +static bool __init acpi_is_processor_usable(u32 lapic_flags) +{ + if (lapic_flags & ACPI_MADT_ENABLED) + return true; + + if (acpi_support_online_capable && (lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) + return true; + + return false; +} + static int __init acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end) { @@ -212,6 +223,10 @@ acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end) if (apic_id == 0xffffffff) return 0; + /* don't register processors that cannot be onlined */ + if (!acpi_is_processor_usable(processor->lapic_flags)) + return 0; + /* * We need to register disabled CPU as well to permit * counting disabled CPUs. This allows us to size @@ -250,9 +265,7 @@ acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end) return 0; /* don't register processors that can not be onlined */ - if (acpi_support_online_capable && - !(processor->lapic_flags & ACPI_MADT_ENABLED) && - !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) + if (!acpi_is_processor_usable(processor->lapic_flags)) return 0; /* -- cgit v1.2.3