diff options
Diffstat (limited to 'arch/x86/boot/compressed/pgtable_64.c')
| -rw-r--r-- | arch/x86/boot/compressed/pgtable_64.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index f8debf7aeb4c..c8862696a47b 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -40,7 +40,6 @@ int cmdline_find_option_bool(const char *option); static unsigned long find_trampoline_placement(void) { unsigned long bios_start = 0, ebda_start = 0; - unsigned long trampoline_start; struct boot_e820_entry *entry; char *signature; int i; @@ -73,6 +72,8 @@ static unsigned long find_trampoline_placement(void) /* Find the first usable memory region under bios_start. */ for (i = boot_params->e820_entries - 1; i >= 0; i--) { + unsigned long new = bios_start; + entry = &boot_params->e820_table[i]; /* Skip all entries above bios_start. */ @@ -85,15 +86,20 @@ static unsigned long find_trampoline_placement(void) /* Adjust bios_start to the end of the entry if needed. */ if (bios_start > entry->addr + entry->size) - bios_start = entry->addr + entry->size; + new = entry->addr + entry->size; /* Keep bios_start page-aligned. */ - bios_start = round_down(bios_start, PAGE_SIZE); + new = round_down(new, PAGE_SIZE); /* Skip the entry if it's too small. */ - if (bios_start - TRAMPOLINE_32BIT_SIZE < entry->addr) + if (new - TRAMPOLINE_32BIT_SIZE < entry->addr) continue; + /* Protect against underflow. */ + if (new - TRAMPOLINE_32BIT_SIZE > bios_start) + break; + + bios_start = new; break; } |