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path: root/arch/x86/kernel/entry_64.S
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2009-03-12x86-64: move save_paranoid into .kprobes.textJan Beulich
Impact: mark save_paranoid as non-kprobe-able code This appears to be necessary as the function gets called from kprobes-unsafe exception handling stubs (i.e. which themselves live in .kprobes.text). Signed-off-by: Jan Beulich <jbeulich@novell.com> LKML-Reference: <49B8F44F.76E4.0078.0@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-12x86: remove leftover unwind annotationsJan Beulich
Impact: cleanup These got left in needlessly when ret_from_fork got simplified. Signed-off-by: Jan Beulich <jbeulich@novell.com> LKML-Reference: <49B8F355.76E4.0078.0@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-04x86: UV, SGI RTC: add generic system vectorDimitri Sivanich
This patch allocates a system interrupt vector for various platform specific uses. Signed-off-by: Dimitri Sivanich <sivanich@sgi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: john stultz <johnstul@us.ibm.com> LKML-Reference: <20090304185605.GA24419@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-26Merge branch 'x86/core' into perfcounters/coreIngo Molnar
Conflicts: arch/x86/kernel/apic/apic.c arch/x86/kernel/irqinit_32.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-24Merge branches 'x86/acpi', 'x86/apic', 'x86/asm', 'x86/cleanups', 'x86/mm', ↵Ingo Molnar
'x86/signal' and 'x86/urgent'; commit 'v2.6.29-rc6' into x86/core
2009-02-24x86: head_64.S - use GLOBAL macroCyrill Gorcunov
Impact: cleanup Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: heukelum@fastmail.fm Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-24x86: entry_64.S - add missing ENDPROCCyrill Gorcunov
native_usergs_sysret64 is described as extern void native_usergs_sysret64(void) so lets add ENDPROC here Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: heukelum@fastmail.fm Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-13x86: use _types.h headers in asm where availableJeremy Fitzhardinge
In general, the only definitions that assembly files can use are in _types.S headers (where available), so convert them. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
2009-02-13Merge branch 'x86/core' into perfcounters/coreIngo Molnar
Conflicts: arch/x86/Kconfig arch/x86/kernel/apic.c arch/x86/kernel/setup_percpu.c
2009-02-11Merge commit 'v2.6.29-rc4' into perfcounters/coreIngo Molnar
Conflicts: arch/x86/kernel/setup_percpu.c arch/x86/mm/fault.c drivers/acpi/processor_idle.c kernel/irq/handle.c
2009-02-09Merge branch 'x86/paravirt' into x86/apicIngo Molnar
Conflicts: arch/x86/mach-voyager/voyager_smp.c
2009-02-05Merge branch 'x86/urgent' into x86/apicIngo Molnar
Conflicts: arch/x86/mach-default/setup.c Semantic merge: arch/x86/kernel/irqinit_32.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-02x86: push old stack address on irqstack for unwinderMartin Hicks
Impact: Fixes dumpstack and KDB on 64 bits This re-adds the old stack pointer to the top of the irqstack to help with unwinding. It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49 as part of the save_args out-of-line work. Both dumpstack and KDB require this information. Signed-off-by: Martin Hicks <mort@sgi.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-01-30x86: fix paravirt clobber in entry_64.SJeremy Fitzhardinge
Impact: Fix latent bug The clobber is trying to say that anything except RDI is available for clobbering, but actually clobbers everything. This hasn't mattered because the clobbers were basically ignored, but subsequent patches will rely on them. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-01-28Merge branches 'x86/asm', 'x86/cleanups', 'x86/cpudetect', 'x86/debug', ↵Ingo Molnar
'x86/doc', 'x86/header-fixes', 'x86/mm', 'x86/paravirt', 'x86/pat', 'x86/setup-v2', 'x86/subarch', 'x86/uaccess' and 'x86/urgent' into x86/core
2009-01-23Merge branch 'core/percpu' into perfcounters/coreIngo Molnar
Conflicts: arch/x86/include/asm/hardirq_32.h arch/x86/include/asm/hardirq_64.h Semantic merge: arch/x86/include/asm/hardirq.h [ added apic_perf_irqs field. ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-21x86: make UV support configurableNick Piggin
Make X86 SGI Ultraviolet support configurable. Saves about 13K of text size on my modest config. text data bss dec hex filename 6770537 1158680 694356 8623573 8395d5 vmlinux 6757492 1157664 694228 8609384 835e68 vmlinux.nouv Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-18Merge branch 'core/percpu' into perfcounters/coreIngo Molnar
Conflicts: arch/x86/include/asm/pda.h We merge tip/core/percpu into tip/perfcounters/core because of a semantic and contextual conflict: the former eliminates the PDA, while the latter extends it with apic_perf_irqs field. Resolve the conflict by moving the new field to the irq_cpustat structure on 64-bit too. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-19x86-64: Move irqcount from PDA to per-cpu.Brian Gerst
tj: s/irqcount/irq_count/ Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-19x86-64: Move oldrsp from PDA to per-cpu.Brian Gerst
tj: * in asm-offsets_64.c, pda.h inclusion shouldn't be removed as pda is still referenced in the file * s/oldrsp/old_rsp/ Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-19x86-64: Move kernelstack from PDA to per-cpu.Brian Gerst
Also clean up PER_CPU_VAR usage in xen-asm_64.S tj: * remove now unused stack_thread_info() * s/kernelstack/kernel_stack/ * added FIXME comment in xen-asm_64.S Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-19x86-64: Convert irqstacks to per-cpuBrian Gerst
Move the irqstackptr variable from the PDA to per-cpu. Make the stacks themselves per-cpu, removing some specific allocation code. Add a seperate flag (is_boot_cpu) to simplify the per-cpu boot adjustments. tj: * sprinkle some underbars around. * irq_stack_ptr is not used till traps_init(), no reason to initialize it early. On SMP, just leaving it NULL till proper initialization in setup_per_cpu_areas() works. Dropped is_boot_cpu and early irq_stack_ptr initialization. * do DECLARE/DEFINE_PER_CPU(char[IRQ_STACK_SIZE], irq_stack) instead of (char, irq_stack[IRQ_STACK_SIZE]). Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-16x86: merge 64 and 32 SMP percpu handlingTejun Heo
Now that pda is allocated as part of percpu, percpu doesn't need to be accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP one. Other than the segment register, operand size and the base of percpu symbols, they behave identical now. This patch replaces now unnecessary pda->data_offset with a dummy field which is necessary to keep stack_canary at its place. This patch also moves per_cpu_offset initialization out of init_gdt() into setup_per_cpu_areas(). Note that this change also necessitates explicit per_cpu_offset initializations in voyager_smp.c. With this change, x86_OP_percpu()'s are as efficient on x86_64 as on x86_32 and also x86_64 can use assembly PER_CPU macros. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-11x86-64: remove locked instruction from switch_to()Benjamin LaHaise
Impact: micro-optimization The patch below removes an unnecessary locked instruction from switch_to(). TIF_FORK is only ever set in copy_thread() on initial process creation, and gets cleared during the first scheduling of the process. As such, it is safe to use an unlocked test for the flag within switch_to(). Signed-off-by: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-29Merge branch 'linus' into perfcounters/coreIngo Molnar
Conflicts: fs/exec.c include/linux/init_task.h Simple context conflicts.
2008-12-28Merge branch 'tracing-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits) sched, trace: update trace_sched_wakeup() tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3 Revert "x86: disable X86_PTRACE_BTS" ring-buffer: prevent false positive warning ring-buffer: fix dangling commit race ftrace: enable format arguments checking x86, bts: memory accounting x86, bts: add fork and exit handling ftrace: introduce tracing_reset_online_cpus() helper tracing: fix warnings in kernel/trace/trace_sched_switch.c tracing: fix warning in kernel/trace/trace.c tracing/ring-buffer: remove unused ring_buffer size trace: fix task state printout ftrace: add not to regex on filtering functions trace: better use of stack_trace_enabled for boot up code trace: add a way to enable or disable the stack tracer x86: entry_64 - introduce FTRACE_ frame macro v2 tracing/ftrace: add the printk-msg-only option tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp() x86, bts: correctly report invalid bts records ... Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits being already partly merged by the SH merge.
2008-12-17x86: entry_64 - introduce FTRACE_ frame macro v2Cyrill Gorcunov
Impact: clean up Itroduce MCOUNT_SAVE/RESTORE_FRAME which allow us to save a number of lines on source level. Also fix a comment in ftrace.h. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-08performance counters: x86 supportIngo Molnar
Implement performance counters for x86 Intel CPUs. It's simplified right now: the PERFMON CPU feature is assumed, which is available in Core2 and later Intel CPUs. The design is flexible to be extended to more CPU types as well. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-03ftrace: function graph return for function entrySteven Rostedt
Impact: feature, let entry function decide to trace or not This patch lets the graph tracer entry function decide if the tracing should be done at the end as well. This requires all function graph entry functions return 1 if it should trace, or 0 if the return should not be traced. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-03ftrace: have function graph use mcount caller addressSteven Rostedt
Impact: consistency change for function graph This patch makes function graph record the mcount caller address the same way the function tracer does. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-02tracing/function-graph-tracer: support for x86-64Frederic Weisbecker
Impact: extend and enable the function graph tracer to 64-bit x86 This patch implements the support for function graph tracer under x86-64. Both static and dynamic tracing are supported. This causes some small CPP conditional asm on arch/x86/kernel/ftrace.c I wanted to use probe_kernel_read/write to make the return address saving/patching code more generic but it causes tracing recursion. That would be perhaps useful to implement a notrace version of these function for other archs ports. Note that arch/x86/process_64.c is not traced, as in X86-32. I first thought __switch_to() was responsible of crashes during tracing because I believed current task were changed inside but that's actually not the case (actually yes, but not the "current" pointer). So I will have to investigate to find the functions that harm here, to enable tracing of the other functions inside (but there is no issue at this time, while process_64.c stays out of -pg flags). A little possible race condition is fixed inside this patch too. When the tracer allocate a return stack dynamically, the current depth is not initialized before but after. An interrupt could occur at this time and, after seeing that the return stack is allocated, the tracer could try to trace it with a random uninitialized depth. It's a prevention, even if I hadn't problems with it. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tim Bird <tim.bird@am.sony.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-28x86: ret_from_fork - get rid of jump backIngo Molnar
Impact: remove dead code If we take a closer look at the rff_trace/rff_action ret_from_fork code, we have to realize that it does all the wrong things: for example it checks the TIF flag - while later on jumping back to the ret-from-syscall path - duplicating the check needlessly. But checking for _TIF_SYSCALL_TRACE is completely unnecessary here because we clear that flag for every freshly forked task. So the whole "tracing" code here, for which there is a out of line jump optimization that makes it even harder to read, is in reality completely dead code ... Reported-by: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Tested-by: Cyrill Gorcunov <gorcunov@gmail.com>
2008-11-28Merge branch 'x86/debug' into x86/irqIngo Molnar
We merge this branch because x86/debug touches code that we started cleaning up in x86/irq. The two branches started out independent, but as unexpected amount of activity went into x86/irq, they became dependent. Resolve that by this cross-merge.
2008-11-28x86: entry_64.S - trivial: space, comments fixupCyrill Gorcunov
Impact: cleanup Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-28x86: uv bau interrupt -- use proper interrupt numberCyrill Gorcunov
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Acked-by: Cliff Wickman <cpw@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-27x86: entry_64.S - use ENTRY to define child_ripCyrill Gorcunov
child_rip is called not by its name but indirectly rather so make it global and aligned. Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Acked-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-27x86: entry_64.S - use X86_EFLAGS_IF instead of hardcoded numbergorcunov@gmail.com
Impact: cleanup Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Acked-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-27x86_64: get rid of the use of KPROBE_ENTRY / KPROBE_ENDAlexander van Heukelum
Impact: clean up assembly macros and annotations - with some object impact entry_64.S is the only user of KPROBE_ENTRY / KPROBE_END on x86_64. This patch reorders entry_64.S and explicitly generates a separate section for functions that need the protection. The generated code before and after the patch is equal. Implicitly changing sections in assembly files makes it more difficult to follow why the assembler is doing certain things. For example, .p2align 5 KPROBE_ENTRY(...) was not doing what you would expect. Other section changes (__ex_table, .fixup, .init.rodata) are done explicitly already. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Acked-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23x86, debug: remove the confusing entry in call tracejia zhang
Impact: improve backtrace quality avoid the confusion in call trace because of the lack of padding at the tail of function. When do_exit gets called, the return address behind call instruction is pushed into stack. If something get wrong in do_exit, for x86_64, the entry "kernel_execve +0x00/0xXX" rather than "child_rip +0xYY/0xZZ" is in the call trace. That looks confusing, so add a u2d to make the return address still part of the original call site. (This also catches any instances of us returning from that function somehow.) Signed-off-by: jia zhang <jia.zhang2008@gmail.com> Acked-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23x86: KPROBE_ENTRY should be paired wth KPROBE_ENDAlexander van Heukelum
Impact: move some code out of .kprobes.text KPROBE_ENTRY switches code generation to .kprobes.text, and KPROBE_END uses .popsection to get back to the previous section (.text, normally). Also replace ENDPROC by END, for consistency. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23x86: include ENTRY/END in entry handlers in entry_64.SAlexander van Heukelum
Impact: cleanup of entry_64.S Except for the order and the place of the functions, this patch should not change the generated code. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23x86: move dwarf2 related macro to dwarf2.hCyrill Gorcunov
Impact: cleanup Move recently introduced dwarf2 macros to dwarf2.h file. It allow us to not duplicate them in assembly files. Active usage of _cfi macros don't make assembly files more obvious to understand but we already have a lot of macros there which requires to search the definitions of them *anyway*. But at least it make every cfi usage one line shorter. Also some code alignment is done. Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-22x86: split out some macro's and move common code to paranoid_exit, fixAlexander van Heukelum
Impact: fix bootup crash Even though it tested fine for me, there was still a bug in the first patch: I have overlooked a call to ptregscall_common. This patch fixes that, I think, but the code is never executed for me while running a debian install... (I tested this by putting an "1:jmp 1b" in there.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-21x86: entry_64.S: split out some macro's and move common code to paranoid_exitAlexander van Heukelum
Impact: cleanup DISABLE_INTERRUPTS(CLBR_NONE)/TRACE_IRQS_OFF is now always executed just before paranoid_exit. Move it there. Split out paranoidzeroentry, paranoiderrorentry, and paranoidzeroentry_ist to get more readable macro's. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-21x86: entry_64.S: factor out save_paranoid and paranoid_exitAlexander van Heukelum
Impact: cleanup, shrink kernel image size Also expand the paranoid_exit0 macro into nmi_exit inside the nmi stub in the case of enabled irq-tracing. This gives a few hundred bytes code size reduction. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-21x86: introduce save_rest and restructure the PTREGSCALL macro in entry_64.SAlexander van Heukelum
Impact: cleanup The save_rest function completes a partial stack frame for use by the PTREGSCALL macro. This also avoids the indirect call in PTREGSCALLs. This adds the macro movq_cfi_restore to hide the CFI_RESTORE annotation when restoring a register from the stack frame. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-21x86: entry_64.S: renameIngo Molnar
Impact: cleanup Rename: CFI_PUSHQ => pushq_cfi CFI_POPQ => popq_cfi CFI_MOVQ => movq_cfi To make it blend better into regular assembly code. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-21x86: clean up after: move entry_64.S register saving out of the macros, fixIngo Molnar
Impact: build fix The break builds with older binutils (2.16.1): arch/x86/kernel/entry_64.S: Assembler messages: arch/x86/kernel/entry_64.S:282: Error: too many positional arguments arch/x86/kernel/entry_64.S:283: Error: too many positional arguments arch/x86/kernel/entry_64.S:284: Error: too many positional arguments arch/x86/kernel/entry_64.S:285: Error: too many positional arguments arch/x86/kernel/entry_64.S:286: Error: too many positional arguments arch/x86/kernel/entry_64.S:287: Error: too many positional arguments arch/x86/kernel/entry_64.S:288: Error: too many positional arguments arch/x86/kernel/entry_64.S:289: Error: too many positional arguments arch/x86/kernel/entry_64.S:290: Error: too many positional arguments Took some time to figure out the detail that GAS chokes on: it's negative offsets. Rearrange the calculations to make sure we never go negative. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-20x86: clean up after: move entry_64.S register saving out of the macrosAlexander van Heukelum
This add-on patch to x86: move entry_64.S register saving out of the macros visually cleans up the appearance of the code by introducing some basic helper macro's. It also adds some cfi annotations which were missing. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-20x86: move entry_64.S register saving out of the macrosAlexander van Heukelum
Here is a combined patch that moves "save_args" out-of-line for the interrupt macro and moves "error_entry" mostly out-of-line for the zeroentry and errorentry macros. The save_args function becomes really straightforward and easy to understand, with the possible exception of the stack switch code, which now needs to copy the return address of to the calling function. Normal interrupts arrive with ((~vector)-0x80) on the stack, which gets adjusted in common_interrupt: <common_interrupt>: (5) addq $0xffffffffffffff80,(%rsp) /* -> ~(vector) */ (4) sub $0x50,%rsp /* space for registers */ (5) callq ffffffff80211290 <save_args> (5) callq ffffffff80214290 <do_IRQ> <ret_from_intr>: ... An apic interrupt stub now look like this: <thermal_interrupt>: (5) pushq $0xffffffffffffff05 /* ~(vector) */ (4) sub $0x50,%rsp /* space for registers */ (5) callq ffffffff80211290 <save_args> (5) callq ffffffff80212b8f <smp_thermal_interrupt> (5) jmpq ffffffff80211f93 <ret_from_intr> Similarly the exception handler register saving function becomes simpler, without the need of any parameter shuffling. The stub for an exception without errorcode looks like this: <overflow>: (6) callq *0x1cad12(%rip) # ffffffff803dd448 <pv_irq_ops+0x38> (2) pushq $0xffffffffffffffff /* no syscall */ (4) sub $0x78,%rsp /* space for registers */ (5) callq ffffffff8030e3b0 <error_entry> (3) mov %rsp,%rdi /* pt_regs pointer */ (2) xor %esi,%esi /* no error code */ (5) callq ffffffff80213446 <do_overflow> (5) jmpq ffffffff8030e460 <error_exit> And one for an exception with errorcode like this: <segment_not_present>: (6) callq *0x1cab92(%rip) # ffffffff803dd448 <pv_irq_ops+0x38> (4) sub $0x78,%rsp /* space for registers */ (5) callq ffffffff8030e3b0 <error_entry> (3) mov %rsp,%rdi /* pt_regs pointer */ (5) mov 0x78(%rsp),%rsi /* load error code */ (9) movq $0xffffffffffffffff,0x78(%rsp) /* no syscall */ (5) callq ffffffff80213209 <do_segment_not_present> (5) jmpq ffffffff8030e460 <error_exit> Unfortunately, this last type is more than 32 bytes. But the total space savings due to this patch is about 2500 bytes on an smp-configuration, and I think the code is clearer than it was before. The tested kernels were non-paravirt ones (i.e., without the indirect call at the top of the exception handlers). Anyhow, I tested this patch on top of a recent -tip. The machine was an 2x4-core Xeon at 2333MHz. Measured where the delays between (almost-)adjacent rdtsc instructions. The graphs show how much time is spent outside of the program as a function of the measured delay. The area under the graph represents the total time spent outside the program. Eight instances of the rdtsctest were started, each pinned to a single cpu. The histogams are added. For each kernel two measurements were done: one in mostly idle condition, the other while running "bonnie++ -f", bound to cpu 0. Each measurement took 40 minutes runtime. See the attached graphs for the results. The graphs overlap almost everywhere, but there are small differences. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>