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b87cf63e2a
linux/arch/x86/kernel
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Denys Vlasenko b87cf63e2a x86/asm/entry: Add comments about various syscall instructions 
SYSCALL/SYSRET and SYSENTER/SYSEXIT have weird semantics.
Moreover, they differ in 32- and 64-bit mode.

What is saved? What is not? Is rsp set? Are interrupts disabled?
People tend to not remember these details well enough.

This patch adds comments which explain in detail
what registers are modified by each of these instructions.

The comments are placed immediately before corresponding
entry and exit points.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/a94b98b63527797c871a81402ff5060b18fa880a.1424989793.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-04 22:50:51 +01:00
..
acpi Merge branches 'core-urgent-for-linus' and 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-21 10:36:06 -08:00
apic Revert "x86/apic: Only disable CPU x2apic mode when necessary" 2015-02-13 10:26:18 -08:00
cpu A more involved rework of the alternatives framework to be able to 2015-03-04 06:36:15 +01:00
kprobes Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-03-01 11:56:13 -08:00
.gitignore
alternative.c x86/alternatives: Use optimized NOPs for padding 2015-02-23 13:44:12 +01:00
amd_gart_64.c x86: enable DMA CMA with swiotlb 2014-06-04 16:53:57 -07:00
amd_nb.c x86, amd_nb: Add device IDs to NB tables for F15h M60h 2014-10-20 14:18:45 +02:00
apb_timer.c x86/platform: Remove unused function from apb_timer.c 2014-12-23 10:43:35 +01:00
aperture_64.c x86/gart: Tidy messages and add bridge device info 2014-05-23 10:47:19 -06:00
apm_32.c cpuidle: Invert CPUIDLE_FLAG_TIME_VALID logic 2014-11-12 21:17:27 +01:00
asm-offsets_32.c x86/asm: Guard against building the 32/64-bit versions of the asm-offsets*.c file directly 2014-12-11 11:43:56 +01:00
asm-offsets_64.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-14 11:51:50 -08:00
asm-offsets.c sched, x86: Provide a per-cpu preempt_count implementation 2013-09-25 14:07:57 +02:00
audit_64.c x86: hook up execveat system call 2014-12-13 12:42:51 -08:00
bootflag.c
check.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
cpuid.c x86, cpuid: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:51 -07:00
crash_dump_32.c
crash_dump_64.c
crash.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
devicetree.c x86, irq, devicetree: Release IOAPIC pin when PCI device is disabled 2014-06-21 23:05:44 +02:00
doublefault.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
dumpstack_32.c Merge branch 'x86-threadinfo-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01 10:17:18 -07:00
dumpstack_64.c x86_64, traps: Stop using IST for #SS 2014-11-23 13:56:19 -08:00
dumpstack.c x86_64: add KASan support 2015-02-13 21:21:41 -08:00
e820.c x86, e820: Clean up sanitize_e820_map() users 2015-01-23 16:14:27 +01:00
early_printk.c Specify PCI based UART for earlyprintk 2015-02-02 10:11:27 -08:00
early-quirks.c drm/i915/skl: Add the additional graphics stolen sizes 2014-09-24 14:47:39 +02:00
entry_32.S x86/asm: Introduce push/pop macros which generate CFI_REL_OFFSET and CFI_RESTORE 2015-03-04 22:50:49 +01:00
entry_64.S x86/asm/entry: Add comments about various syscall instructions 2015-03-04 22:50:51 +01:00
espfix_64.c x86, espfix: Remove stale ptemask 2014-11-11 17:57:46 +01:00
ftrace.c module: remove mod arg from module_free, rename module_memfree(). 2015-01-20 11:38:33 +10:30
head32.c x86: Store a per-cpu shadow copy of CR4 2015-02-04 12:10:42 +01:00
head64.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-16 14:58:12 -08:00
head_32.S x86/asm/boot: Use already defined KEEP_SEGMENTS macro in head_{32,64}.S 2015-02-19 10:05:04 +01:00
head_64.S Linux 4.0-rc2 2015-03-04 06:35:43 +01:00
head.c
hpet.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
hw_breakpoint.c perf/x86: Remove get_hbp_len and replace with bp_len 2014-12-03 15:14:30 +01:00
i386_ksyms_32.c sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
i387.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-16 14:58:12 -08:00
i8237.c
i8253.c
i8259.c x86/irq: Fix XT-PIC-XT-PIC in /proc/interrupts 2014-10-28 12:01:08 +01:00
io_delay.c
ioport.c
iosf_mbi.c x86/platform/intel/iosf: Add debugfs config option for IOSF 2014-09-19 13:08:43 +02:00
irq_32.c x86: Clean up current_stack_pointer 2015-01-02 10:22:46 -08:00
irq_64.c x86: Replace __get_cpu_var uses 2014-08-26 13:45:49 -04:00
irq_work.c x86: Tell irq work about self IPI support 2014-09-13 18:38:29 +02:00
irq.c x86/irq: Check for valid irq descriptor in check_irq_vectors_for_cpu_disable() 2015-02-18 15:01:42 +01:00
irqinit.c x86, irq: Move local APIC related code from io_apic.c into vector.c 2014-12-16 14:08:16 +01:00
jump_label.c x86/jump_label: expect default_nop if static_key gets enabled on boot-up 2013-10-19 19:45:35 -04:00
kdebugfs.c
kexec-bzimage64.c kexec-bzimage64: fix sparse warnings 2014-10-14 02:18:21 +02:00
kgdb.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
ksysfs.c x86: ksysfs.c build fix 2014-01-03 14:37:13 +00:00
kvm.c x86/spinlocks/paravirt: Fix memory corruption on unlock 2015-02-18 14:53:49 +01:00
kvmclock.c x86, kvm: Clear paravirt_enabled on KVM guests for espfix32's benefit 2014-12-10 12:49:39 +01:00
ldt.c Revert "x86-64, modify_ldt: Make support for 16-bit segments a runtime option" 2014-05-21 10:22:59 -07:00
livepatch.c livepatch: kernel: add support for live patching 2014-12-22 15:40:49 +01:00
machine_kexec_32.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
machine_kexec_64.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
Makefile Linux 4.0-rc2 2015-03-04 06:35:43 +01:00
mcount_64.S ftrace/fgraph/x86: Have prepare_ftrace_return() take ip as first parameter 2014-12-01 14:08:58 -05:00
mmconf-fam10h_64.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
module.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-21 10:41:29 -08:00
mpparse.c x86, apic: Remove mps_oem_check callback 2014-07-31 08:05:42 -07:00
msr.c x86, msr: Use seek definitions instead of hard-coded values 2014-10-17 13:40:55 -07:00
nmi_selftest.c
nmi.c kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation 2014-04-24 10:26:38 +02:00
paravirt_patch_32.c
paravirt_patch_64.c x86_64/entry/xen: Do not invoke espfix64 on Xen 2014-07-28 15:25:40 -07:00
paravirt-spinlocks.c x86, ticketlock: Add slowpath logic 2013-08-09 07:54:00 -07:00
paravirt.c kprobes, x86: Prohibit probing on native_set_debugreg()/load_idt() 2014-04-24 10:02:58 +02:00
pci-calgary_64.c x86, calgary: Use 8M TCE table size by default 2014-04-10 19:51:32 -07:00
pci-dma.c arch/x86/kernel/pci-dma.c: fix dma_generic_alloc_coherent() when CONFIG_DMA_CMA is enabled 2014-06-04 16:53:57 -07:00
pci-iommu_table.c
pci-nommu.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
pci-swiotlb.c x86: enable DMA CMA with swiotlb 2014-06-04 16:53:57 -07:00
pcspeaker.c
perf_regs.c perf/x86_64: Improve user regs sampling 2015-01-09 11:12:29 +01:00
pmc_atom.c x86: pmc_atom: Expose contents of PSS 2015-01-20 12:50:14 +01:00
probe_roms.c
process_32.c x86: Store a per-cpu shadow copy of CR4 2015-02-04 12:10:42 +01:00
process_64.c Linux 4.0-rc2 2015-03-04 06:35:43 +01:00
process.c x86: Clean up cr4 manipulation 2015-02-04 12:10:41 +01:00
ptrace.c x86/ptrace: Remove checks for TIF_IA32 when changing CS and SS 2015-02-25 08:27:49 +01:00
pvclock.c hung_task: add method to reset detector 2013-11-06 09:49:02 +02:00
quirks.c x86: HPET force enable for e6xx based systems 2014-09-15 17:53:35 -07:00
reboot_fixups_32.c
reboot.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
relocate_kernel_32.S x86, asm, cleanup: Replace open-coded control register values with symbolic 2013-06-25 16:26:06 -07:00
relocate_kernel_64.S x86, reloc: Use xorl instead of xorq in relocate_kernel_64.S 2013-06-20 21:30:04 -07:00
resource.c x86: don't exclude low BIOS area when allocating address space for non-PCI cards 2014-07-16 12:29:36 -06:00
rtc.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
setup_percpu.c x86: Convert a few more per-CPU items to read-mostly ones 2014-11-04 20:13:28 +01:00
setup.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-02-21 10:41:29 -08:00
signal.c all arches, signal: move restart_block to struct task_struct 2015-02-12 18:54:12 -08:00
smp.c asmlinkage, x86: Add explicit __visible to arch/x86/* 2014-05-05 16:07:44 -07:00
smpboot.c x86: Consolidate boot cpu timer setup 2015-01-22 15:10:56 +01:00
stacktrace.c
step.c
sys_x86_64.c x86 get_unmapped_area: Access mmap_legacy_base through mm_struct member 2013-08-22 10:19:35 -07:00
syscall_32.c x86/compat: Merge native and compat 32-bit syscall tables 2015-03-04 06:16:21 +01:00
syscall_64.c x86, asmlinkage: Make syscall tables visible 2013-08-06 14:20:18 -07:00
sysfb_efi.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
sysfb_simplefb.c x86/simplefb: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:52 -07:00
sysfb.c x86/sysfb: Use PTR_ERR_OR_ZERO 2014-10-17 13:40:52 -07:00
tboot.c x86 / tboot / ACPI: Fail extended mode reduced hardware sleep 2013-07-31 14:25:51 +02:00
tce_64.c
test_nx.c
test_rodata.c
time.c x86_64/vdso: Remove jiffies from the vvar page 2014-10-28 11:22:13 +01:00
tls.c x86, tls: Interpret an all-zero struct user_desc as "no segment" 2015-01-22 21:45:07 +01:00
tls.h
topology.c hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock() 2013-09-30 19:55:51 +02:00
trace_clock.c
tracepoint.c x86: Make sure IDT is page aligned 2013-07-16 15:14:48 -07:00
traps.c x86/traps: Enable DEBUG_STACK after cpu_init() for TRAP_DB/BP 2015-02-26 12:29:20 +01:00
tsc_msr.c x86: tsc: Add missing Baytrail frequency to the table 2014-02-19 17:12:24 +01:00
tsc_sync.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
tsc.c x86/tsc: Change Fast TSC calibration failed from error to info 2015-01-23 10:53:52 +01:00
uprobes.c uprobes/x86: Fix 2-byte opcode table 2015-02-18 20:55:53 +01:00
verify_cpu.S
vm86_32.c
vmlinux.lds.S x86-64: Use RIP-relative addressing for most per-CPU accesses 2014-11-04 20:43:14 +01:00
vsmp_64.c x86/apic/vsmp: Make is_vsmp_box() static 2014-08-01 15:09:45 -07:00
vsyscall_64.c x86_64/vsyscall: Restore orig_ax after vsyscall seccomp 2014-11-10 10:46:35 +01:00
vsyscall_emu_64.S
vsyscall_gtod.c timekeeping: Create struct tk_read_base and use it in struct timekeeper 2014-07-23 15:01:53 -07:00
vsyscall_trace.h
x86_init.c Revert "PCI: Add x86_msi.msi_mask_irq() and msix_mask_irq()" 2014-11-11 15:14:30 -07:00
x8664_ksyms_64.c x86_64: kasan: add interceptors for memset/memmove/memcpy functions 2015-02-13 21:21:41 -08:00
xsave.c x86: Clean up cr4 manipulation 2015-02-04 12:10:41 +01:00