From 084ee1c641a068bfd1194d545f7dc9ab2043eb35 Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Tue, 8 May 2012 21:22:26 +0300 Subject: [PATCH] x86, realmode: Relocator for realmode code Implements relocator for real mode code that is called as part of setup_arch(). Processes segment relocations and linear relocations. Real-mode code is relocated to a free hole below 1 MB. Signed-off-by: Jarkko Sakkinen Link: http://lkml.kernel.org/r/1336501366-28617-4-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/realmode.h | 26 +++++++++++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/realmode.c | 79 +++++++++++++++++++++++++++++++++ arch/x86/kernel/setup.c | 2 + 4 files changed, 108 insertions(+) create mode 100644 arch/x86/include/asm/realmode.h create mode 100644 arch/x86/kernel/realmode.c diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h new file mode 100644 index 000000000000..dc1bba534c14 --- /dev/null +++ b/arch/x86/include/asm/realmode.h @@ -0,0 +1,26 @@ +#ifndef _ARCH_X86_REALMODE_H +#define _ARCH_X86_REALMODE_H + +#include +#include + +/* This must match data at realmode.S */ +struct real_mode_header { + u32 text_start; + u32 ro_end; + u32 end; +} __attribute__((__packed__)); + +extern struct real_mode_header real_mode_header; +extern unsigned char *real_mode_base; + +extern unsigned long init_rsp; +extern unsigned long initial_code; +extern unsigned long initial_gs; + +extern unsigned char real_mode_blob[]; +extern unsigned char real_mode_relocs[]; + +extern void __init setup_real_mode(void); + +#endif /* _ARCH_X86_REALMODE_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 532d2e090e6f..f9e19d4eb984 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -36,6 +36,7 @@ obj-y += pci-iommu_table.o obj-y += resource.o obj-y += trampoline.o trampoline_$(BITS).o +obj-y += realmode.o obj-y += process.o obj-y += i387.o xsave.o obj-y += ptrace.o diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c new file mode 100644 index 000000000000..7415c42547ac --- /dev/null +++ b/arch/x86/kernel/realmode.c @@ -0,0 +1,79 @@ +#include +#include + +#include +#include +#include + +unsigned char *real_mode_base; +struct real_mode_header real_mode_header; + +void __init setup_real_mode(void) +{ + phys_addr_t mem; + u16 real_mode_seg; + u32 *rel; + u32 count; + u32 *ptr; + u16 *seg; + int i; + + struct real_mode_header *header = + (struct real_mode_header *) real_mode_blob; + + size_t size = PAGE_ALIGN(header->end); + + /* Has to be in very low memory so we can execute real-mode AP code. */ + mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE); + if (!mem) + panic("Cannot allocate trampoline\n"); + + real_mode_base = __va(mem); + memblock_reserve(mem, size); + + printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n", + real_mode_base, (unsigned long long)mem, size); + + memcpy(real_mode_base, real_mode_blob, size); + + real_mode_seg = __pa(real_mode_base) >> 4; + rel = (u32 *) real_mode_relocs; + + /* 16-bit segment relocations. */ + count = rel[0]; + rel = &rel[1]; + for (i = 0; i < count; i++) { + seg = (u16 *) (real_mode_base + rel[i]); + *seg = real_mode_seg; + } + + /* 32-bit linear relocations. */ + count = rel[i]; + rel = &rel[i + 1]; + for (i = 0; i < count; i++) { + ptr = (u32 *) (real_mode_base + rel[i]); + *ptr += __pa(real_mode_base); + } + + /* Copied header will contain relocated physical addresses. */ + memcpy(&real_mode_header, real_mode_base, + sizeof(struct real_mode_header)); +} + +/* + * set_real_mode_permissions() gets called very early, to guarantee the + * availability of low memory. This is before the proper kernel page + * tables are set up, so we cannot set page permissions in that + * function. Thus, we use an arch_initcall instead. + */ +static int __init set_real_mode_permissions(void) +{ + size_t all_size = + PAGE_ALIGN(real_mode_header.end) - + __pa(real_mode_base); + + set_memory_x((unsigned long) real_mode_base, all_size >> PAGE_SHIFT); + return 0; +} + +arch_initcall(set_real_mode_permissions); diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 1a2901562059..56e41242a6b8 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -74,6 +74,7 @@ #include #include #include +#include #include #include #include @@ -918,6 +919,7 @@ void __init setup_arch(char **cmdline_p) max_pfn_mapped<