kernel.git/arch/x86/kernel/head_64.S, branch linux-3.17.y

x86: fix compile error due to X86_TRAP_NMI use in asm files

2014-03-08T02:58:40Z

It's an enum, not a #define, you can't use it in asm files. Introduced in commit 5fa10196bdb5 ("x86: Ignore NMIs that come in during early boot"), and sadly I didn't compile-test things like I should have before pushing out. My weak excuse is that the x86 tree generally doesn't introduce stupid things like this (and the ARM pull afterwards doesn't cause me to do a compile-test either, since I don't cross-compile). Cc: Don Zickus Cc: H. Peter Anvin Signed-off-by: Linus Torvalds

x86: Ignore NMIs that come in during early boot

2014-03-07T23:08:14Z

Don Zickus reports: A customer generated an external NMI using their iLO to test kdump worked. Unfortunately, the machine hung. Disabling the nmi_watchdog made things work. I speculated the external NMI fired, caused the machine to panic (as expected) and the perf NMI from the watchdog came in and was latched. My guess was this somehow caused the hang. ---- It appears that the latched NMI stays latched until the early page table generation on 64 bits, which causes exceptions to happen which end in IRET, which re-enable NMI. Therefore, ignore NMIs that come in during early execution, until we have proper exception handling. Reported-and-tested-by: Don Zickus Link: http://lkml.kernel.org/r/1394221143-29713-1-git-send-email-dzickus@redhat.com Signed-off-by: H. Peter Anvin Cc: # v3.5+, older with some backport effort

x86: Make sure IDT is page aligned

2013-07-16T22:14:48Z

Since the IDT is referenced from a fixmap, make sure it is page aligned. Merge with 32-bit one, since it was already aligned to deal with F00F bug. Since bss is cleared before IDT setup, it can live there. This also moves the other *_idt_table variables into common locations. This avoids the risk of the IDT ever being moved in the bss and having the mapping be offset, resulting in calling incorrect handlers. In the current upstream kernel this is not a manifested bug, but heavily patched kernels (such as those using the PaX patch series) did encounter this bug. The tables other than idt_table technically do not need to be page aligned, at least not at the current time, but using a common declaration avoids mistakes. On 64 bits the table is exactly one page long, anyway. Signed-off-by: Kees Cook Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net Reported-by: PaX Team Signed-off-by: H. Peter Anvin

x86, trace: Add irq vector tracepoints

2013-06-21T05:25:34Z

[Purpose of this patch] As Vaibhav explained in the thread below, tracepoints for irq vectors are useful. http://www.spinics.net/lists/mm-commits/msg85707.html The current interrupt traces from irq_handler_entry and irq_handler_exit provide when an interrupt is handled. They provide good data about when the system has switched to kernel space and how it affects the currently running processes. There are some IRQ vectors which trigger the system into kernel space, which are not handled in generic IRQ handlers. Tracing such events gives us the information about IRQ interaction with other system events. The trace also tells where the system is spending its time. We want to know which cores are handling interrupts and how they are affecting other processes in the system. Also, the trace provides information about when the cores are idle and which interrupts are changing that state. On the other hand, my usecase is tracing just local timer event and getting a value of instruction pointer. I suggested to add an argument local timer event to get instruction pointer before. But there is another way to get it with external module like systemtap. So, I don't need to add any argument to irq vector tracepoints now. [Patch Description] Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events. But there is an above use case to trace specific irq_vector rather than tracing all events. In this case, we are concerned about overhead due to unwanted events. So, add following tracepoints instead of introducing irq_vector_entry/exit. so that we can enable them independently. - local_timer_vector - reschedule_vector - call_function_vector - call_function_single_vector - irq_work_entry_vector - error_apic_vector - thermal_apic_vector - threshold_apic_vector - spurious_apic_vector - x86_platform_ipi_vector Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty makes a zero when tracepoints are disabled. Detailed explanations are as follows. - Create trace irq handlers with entering_irq()/exiting_irq(). - Create a new IDT, trace_idt_table, at boot time by adding a logic to _set_gate(). It is just a copy of original idt table. - Register the new handlers for tracpoints to the new IDT by introducing macros to alloc_intr_gate() called at registering time of irq_vector handlers. - Add checking, whether irq vector tracing is on/off, into load_current_idt(). This has to be done below debug checking for these reasons. - Switching to debug IDT may be kicked while tracing is enabled. - On the other hands, switching to trace IDT is kicked only when debugging is disabled. In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being used for other purposes. Signed-off-by: Seiji Aguchi Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com Signed-off-by: H. Peter Anvin Cc: Steven Rostedt

x86: Rename variables for debugging

2013-06-21T05:25:13Z

Rename variables for debugging to describe meaning of them precisely. Also, introduce a generic way to switch IDT by checking a current state, debug on/off. Signed-off-by: Seiji Aguchi Link: http://lkml.kernel.org/r/51C323A8.7050905@hds.com Signed-off-by: H. Peter Anvin Cc: Steven Rostedt

x86-64, init: Fix a possible wraparound bug in switchover in head_64.S

2013-05-28T22:41:59Z

In head_64.S, a switchover has been used to handle kernel crossing 1G, 512G boundaries. And commit 8170e6bed465b4b0c7687f93e9948aca4358a33b x86, 64bit: Use a #PF handler to materialize early mappings on demand said: During the switchover in head_64.S, before #PF handler is available, we use three pages to handle kernel crossing 1G, 512G boundaries with sharing page by playing games with page aliasing: the same page is mapped twice in the higher-level tables with appropriate wraparound. But from the switchover code, when we set up the PUD table: 114 addq $4096, %rdx 115 movq %rdi, %rax 116 shrq $PUD_SHIFT, %rax 117 andl $(PTRS_PER_PUD-1), %eax 118 movq %rdx, (4096+0)(%rbx,%rax,8) 119 movq %rdx, (4096+8)(%rbx,%rax,8) It seems line 119 has a potential bug there. For example, if the kernel is loaded at physical address 511G+1008M, that is 000000000 111111111 111111000 000000000000000000000 and the kernel _end is 512G+2M, that is 000000001 000000000 000000001 000000000000000000000 So in this example, when using the 2nd page to setup PUD (line 114~119), rax is 511. In line 118, we put rdx which is the address of the PMD page (the 3rd page) into entry 511 of the PUD table. But in line 119, the entry we calculate from (4096+8)(%rbx,%rax,8) has exceeded the PUD page. IMO, the entry in line 119 should be wraparound into entry 0 of the PUD table. The patch fixes the bug. Signed-off-by: Zhang Yanfei Link: http://lkml.kernel.org/r/5191DE5A.3020302@cn.fujitsu.com Signed-off-by: Yinghai Lu Cc: v3.9 Signed-off-by: H. Peter Anvin

x86-64, init: Do not set NX bits on non-NX capable hardware

2013-05-02T18:27:35Z

During early init, we would incorrectly set the NX bit even if the NX feature was not supported. Instead, only set this bit if NX is actually available and enabled. We already do very early detection of the NX bit to enable it in EFER, this simply extends this detection to the early page table mask. Reported-by: Fernando Luis Vázquez Cao Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/1367476850.5660.2.camel@nexus Cc: v3.9

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-02-28T00:16:39Z

Pull more x86 fixes from Peter Anvin: "Additional x86 fixes. Three of these patches are pure documentation, two are pretty trivial; the remaining one fixes boot problems on some non-BIOS machines." * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86: Make sure we can boot in the case the BDA contains pure garbage x86, efi: Mark disable_runtime as __initdata x86, doc: Fix incorrect comment about 64-bit code segment descriptors doc, kernel-parameters: Document 'console=hvc' doc, xen: Mention 'earlyprintk=xen' in the documentation. ACPI: Overriding ACPI tables via initrd only works with an initrd and on X86

x86, doc: Fix incorrect comment about 64-bit code segment descriptors

2013-02-25T21:42:37Z

The AMD64 Architecture Programmer's Manual Volume 2, on page 89 mentions: "If the processor is running in 64-bit mode (L=1), the only valid setting of the D bit is 0." This matches with what the code does. Signed-off-by: Konrad Rzeszutek Wilk Link: http://lkml.kernel.org/r/1361825650-14031-4-git-send-email-konrad.wilk@oracle.com Signed-off-by: H. Peter Anvin

x86-64: don't set the early IDT to point directly to 'early_idt_handler'

2013-02-22T21:09:51Z

The code requires the use of the proper per-exception-vector stub functions (set up as the early_idt_handlers[] array - note the 's') that make sure to set up the error vector number. This is true regardless of whether CONFIG_EARLY_PRINTK is set or not. Why? The stack offset for the comparison of __KERNEL_CS won't be right otherwise, nor will the new check (from commit 8170e6bed465: "x86, 64bit: Use a #PF handler to materialize early mappings on demand") for the page fault exception vector. Acked-by: H. Peter Anvin Signed-off-by: Linus Torvalds