Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH 2/3] x86/apic: Make apic_version[] smaller | Date | Fri, 2 Oct 2015 21:12:24 +0200 |
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apic_version[] array is changed from int to u8 - APIC version values as of year 2015 are no larger than 0x1f on all known CPUs.
A bit of code added to ensure that the statement apic_version[apicid] = version; in generic_processor_info() is safe wrt bad values in both 'apicid' and 'version' variables.
This reduces apic_version[] from 128 kbytes to 32.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: Ingo Molnar <mingo@kernel.org> CC: Daniel J Blueman <daniel@numascale.com> CC: Jiang Liu <jiang.liu@linux.intel.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Len Brown <len.brown@intel.com> CC: x86@kernel.org CC: linux-kernel@vger.kernel.org --- arch/x86/include/asm/mpspec.h | 2 +- arch/x86/kernel/apic/apic.c | 19 ++++++++++++++++++- 2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h index e84e542..83140ab 100644 --- a/arch/x86/include/asm/mpspec.h +++ b/arch/x86/include/asm/mpspec.h @@ -6,7 +6,7 @@ #include <asm/x86_init.h> #include <asm/apicdef.h> -extern int apic_version[]; +extern u8 apic_version[]; extern int pic_mode; #ifdef CONFIG_X86_32 diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index b08b447..d0f135c 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1798,7 +1798,7 @@ void __init register_lapic_address(unsigned long address) } } -int apic_version[MAX_LOCAL_APICID]; +u8 apic_version[MAX_LOCAL_APICID]; /* * Local APIC interrupts @@ -2054,6 +2054,23 @@ int generic_processor_info(int apicid, int version) return -EINVAL; } + if ((unsigned)apicid >= ARRAY_SIZE(apic_version)) { + int thiscpu = max + disabled_cpus; + pr_warning("APIC: APIC id 0x%x is too large." + " Processor %d ignored.\n", + apicid, thiscpu); + disabled_cpus++; + return -EINVAL; + } + if ((unsigned)version > 255) { + int thiscpu = max + disabled_cpus; + pr_warning("APIC: APIC version 0x%x is too large." + " Processor %d ignored.\n", + version, thiscpu); + disabled_cpus++; + return -EINVAL; + } + num_processors++; if (apicid == boot_cpu_physical_apicid) { /* -- 1.8.1.4
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