Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Thomas Gleixner:
"A single fix, which addresses boot failures on machines which do not
report EBDA correctly, which can place the trampoline into reserved
memory regions. Validating against E820 prevents that"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot/compressed/64: Validate trampoline placement against E820
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-18
+55
-18
arch/x86/boot/compressed/pgtable_64.c
+55
-18
arch/x86/boot/compressed/pgtable_64.c
···
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#include <asm/e820/types.h>
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#include <asm/processor.h>
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#include "pgtable.h"
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#include "../string.h"
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extern struct boot_params *boot_params;
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int cmdline_find_option_bool(const char *option);
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static unsigned long find_trampoline_placement(void)
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{
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unsigned long bios_start, ebda_start;
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unsigned long trampoline_start;
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struct boot_e820_entry *entry;
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int i;
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/*
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* Find a suitable spot for the trampoline.
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* This code is based on reserve_bios_regions().
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*/
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ebda_start = *(unsigned short *)0x40e << 4;
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bios_start = *(unsigned short *)0x413 << 10;
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if (bios_start < BIOS_START_MIN || bios_start > BIOS_START_MAX)
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bios_start = BIOS_START_MAX;
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if (ebda_start > BIOS_START_MIN && ebda_start < bios_start)
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bios_start = ebda_start;
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bios_start = round_down(bios_start, PAGE_SIZE);
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/* Find the first usable memory region under bios_start. */
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for (i = boot_params->e820_entries - 1; i >= 0; i--) {
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entry = &boot_params->e820_table[i];
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/* Skip all entries above bios_start. */
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if (bios_start <= entry->addr)
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continue;
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/* Skip non-RAM entries. */
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if (entry->type != E820_TYPE_RAM)
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continue;
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/* Adjust bios_start to the end of the entry if needed. */
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if (bios_start > entry->addr + entry->size)
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bios_start = entry->addr + entry->size;
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/* Keep bios_start page-aligned. */
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bios_start = round_down(bios_start, PAGE_SIZE);
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/* Skip the entry if it's too small. */
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if (bios_start - TRAMPOLINE_32BIT_SIZE < entry->addr)
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continue;
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break;
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}
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/* Place the trampoline just below the end of low memory */
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return bios_start - TRAMPOLINE_32BIT_SIZE;
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}
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struct paging_config paging_prepare(void *rmode)
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{
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struct paging_config paging_config = {};
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unsigned long bios_start, ebda_start;
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/* Initialize boot_params. Required for cmdline_find_option_bool(). */
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boot_params = rmode;
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paging_config.l5_required = 1;
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}
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/*
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* Find a suitable spot for the trampoline.
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* This code is based on reserve_bios_regions().
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*/
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ebda_start = *(unsigned short *)0x40e << 4;
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bios_start = *(unsigned short *)0x413 << 10;
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if (bios_start < BIOS_START_MIN || bios_start > BIOS_START_MAX)
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bios_start = BIOS_START_MAX;
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if (ebda_start > BIOS_START_MIN && ebda_start < bios_start)
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bios_start = ebda_start;
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/* Place the trampoline just below the end of low memory, aligned to 4k */
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paging_config.trampoline_start = bios_start - TRAMPOLINE_32BIT_SIZE;
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paging_config.trampoline_start = round_down(paging_config.trampoline_start, PAGE_SIZE);
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paging_config.trampoline_start = find_trampoline_placement();
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trampoline_32bit = (unsigned long *)paging_config.trampoline_start;
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