Messages in this thread Patch in this message | | | Date | Tue, 15 Feb 2011 20:31:22 +0300 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 10/26] x86-64, NUMA: Move apicid to numa mapping initialization from amd_scan_nodes() to amd_numa_init() |
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On 02/15/2011 12:36 PM, Tejun Heo wrote: ... >> >> Hi Tejun, while you at it, it seems apicid_base conditional assignment is >> redundant here (boot_cpu_physical_apicid is unsigned int) so we might have >> something like >> >> apicid_start = boot_cpu_physical_apicid; >> apicid_end = apicid_start + cores; >> >> for_each_node_mask(i, cpu_nodes_parsed) { >> for (j = apicid_start; j< apicid_end; j++) >> set_apicid_to_node((i<< bits) + j, i); >> } > > Right, I think the intention there was > > if (boot_cpu_physical_apicid == -1U) > > because that's the initial value and we don't really want to index the > apicid nid table with -1U. Care to send a patch? I'm gonna have to > rebase anyway and can put the patch at the front. > > Thanks. >
Hi Tejun again :) I've looked some more and if I'm not missing something (Yinghai?) the code is broken in another way. We might have AMD system with corrupted MADT table so boot_cpu_physical_apicid remains =-1U and then we better BUG_ON instead of possible access of out-of-range __apicid_to_node array. If MADT is parsed successfully boot_cpu_physical_apicid will have correct value. So I think we rather should add something like the patch below. Again better Yinghai check it first so I would not _miss_ the point that such situation is impossible at all. (And if I'm right we need to check for set_apicid_to_node(apicid, ) never exceed MAX_LOCAL_APIC as well.
Yinghai am I missing something?
-- Cyrill
--- x86, numa: amd -- Check for screwed MADT table
In case if MADT table is corrupted we might end up with boot_cpu_physical_apicid = -1U, corebits > 0 and get out of __apicid_to_node array bound access. Check for boot_cpu_physical_apicid being not default value.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> --- arch/x86/mm/amdtopology_64.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
Index: linux-2.6.git/arch/x86/mm/amdtopology_64.c ===================================================================== --- linux-2.6.git.orig/arch/x86/mm/amdtopology_64.c +++ linux-2.6.git/arch/x86/mm/amdtopology_64.c @@ -271,9 +271,14 @@ int __init amd_scan_nodes(void) bits = boot_cpu_data.x86_coreid_bits; cores = (1<<bits); apicid_base = 0; + /* get the APIC ID of the BSP early for systems with apicid lifting */ early_get_boot_cpu_id(); - if (boot_cpu_physical_apicid > 0) { + if (boot_cpu_physical_apicid == -1U || ) { + pr_err("BAD APIC ID: %02x, NUMA node scaning canceled\n", + boot_cpu_physical_apicid); + return -1; + } else if (boot_cpu_physical_apicid > 0) { pr_info("BSP APIC ID: %02x\n", boot_cpu_physical_apicid); apicid_base = boot_cpu_physical_apicid; }
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