Commit ecda0628 authored Feb 22, 2009 by Yinghai Lu Committed by Ingo Molnar Feb 23, 2009

x86: check mptable physptr with max_low_pfn on 32bit



Impact: fix early crash on LinuxBIOS systems

Kevin O'Connor reported that Coreboot aka LinuxBIOS tries to put
mptable somewhere very high, well above max_low_pfn (below which
BIOSes generally put the mptable), causing a panic.

The BIOS will probably be changed to be compatible with older
Linus versions, but nevertheless the MP-spec does not forbid
an MP-table in arbitrary system RAM, so make sure it all
works even if the table is in an unexpected place.

Check physptr with max_low_pfn * PAGE_SIZE.

Reported-by: Kevin O'Connor <kevin@koconnor.net>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Stefan Reinauer <stepan@coresystems.de>
Cc: coreboot@coreboot.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 8e6dafd6

arch/x86/kernel/mpparse.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -710,14 +710,23 @@ static int __init smp_scan_config(unsigned long base, unsigned long length,
		* of physical memory; so that simply reserving
		* PAGE_SIZE from mpf->physptr yields BUG()
		* in reserve_bootmem.
		* also need to make sure physptr is below than
		* max_low_pfn
		* we don't need reserve the area above max_low_pfn
		*/
		unsigned long end = max_low_pfn * PAGE_SIZE;

		if (mpf->physptr < end) {
		if (mpf->physptr + size > end)
		size = end - mpf->physptr;
		#endif
		reserve_bootmem_generic(mpf->physptr, size,
		BOOTMEM_DEFAULT);
		}
		#else
		reserve_bootmem_generic(mpf->physptr, size,
		BOOTMEM_DEFAULT);
		#endif
		}

		return 1;
		}