Sysret_check system_call_after_swapgs
Websystem_call: syscall instruction from 64-bit code. entry_INT80_compat: int 0x80 from 32-bit or 64-bit code; compat syscall either way. ... , which might have triggered right after a normal entry wrote CS to the stack but before we executed SWAPGS, then the only safe way to check for GS is the slower method: the RDMSR. Therefore, super-atomic ... Websystem_call_after_swapgs is an utter slowpath in any case. The interim fix is below - although it needs more thinking and probably should be done via an ENTRY_UNALIGNED() method as well, for slowpath targets. With that we get this much nicer entry sequence: ffffffff8020be00: 544323 :
Sysret_check system_call_after_swapgs
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Web* after an interrupt and after each system call. * * Normal syscalls and interrupts don't save a full stack frame, this is ... * after the swapgs, so that it can do the swapgs * for the guest and jump here on syscall. */ ... sysret_check: LOCKDEP_SYS_EXIT: DISABLE_INTERRUPTS(CLBR_NONE) WebNMI watchdog: BUG: soft lockup - CPU#2 stuck for 40s! [kworker/2:2:66033] [] system_call_fastpath+0x25/0x2a [] ? …
Web0.71% perf [kernel.kallsyms] [k] system_call_after_swapgs 0.65% perf [kernel.kallsyms] [k] sysret_check 0.63% perf perf [.] dso__find_symbol 0.58% perf [kernel.kallsyms] [k] clear_page_c 0.58% perf [kernel.kallsyms] [k] handle_mm_fault 0.56% perf libc-2.17.so [.] __sigprocmask ... WebApr 19, 2012 · Well, we can take SYSCALL as an example. After the processor saves the RFLAGS and the next instruction after the call, it has to get the ring0 privileged code to be executed, ie the target instruction and stack ptr.
WebSYSRET is a companion instruction to the SYSCALL instruction. It returns from an OS system-call handler to user code at privilege level 3. It does so by loading RIP from RCX … WebSWAPGS exchanges the current GS base register value with the value contained in MSR address C0000102H (IA32_KERNEL_GS_BASE). The SWAPGS instruction is a privileged …
WebCore part is calling *sys_call_table(, %rax, 8). sys_call_table is an array of addresses of system calls, and rax has system call number and 8 is size of one entry of the table. The entry point of all system calls are the same but call *sys_call_table(, %rax, 8) instruction jumps to corresponding system call. Where is sys_call_table?
WebJun 24, 2024 · swapgs exists because syscall doesn't change RSP to point at the kernel stack (and doesn't save the user-space RSP anywhere). So you need some kind of thread … dj vitoto online downloadWebNov 7, 2024 · Linux kernel for Nexus 5 (hammerhead) Toggle navigation Toggle navigation pinning dj vitaoWebOct 9, 2024 · Как удалить папку $ SysReset в Windows 10. Удаление папки SysReset полностью безопасно, поскольку она содержит только файлы журнала неудачной … dj visualizer programsWebNov 19, 2024 · 0.78% presto-server [kernel.kallsyms] [k] system_call_after_swapgs 0.68% presto-server [kernel.kallsyms] [k] sysret_check 0.65% presto-server libzip.so [.] … dj vitoto omgWebLKML Archive on lore.kernel.org help / color / mirror / Atom feed From: Mike Galbraith To: Suresh Siddha Cc: Peter Zijlstra , linux-kernel , Ingo Molnar , Paul Turner Subject: [patch 1/6] sched: use … dj visualizationsWebApr 19, 2015 · You can patch every call and ret instructions in kernel with call my_tracing_routine and record instruction pointer there, than pass control to original callee/caller. There are tools for that: LTTng, SystemTap, and in-kernel interfaces like kprobes, ftrace... This approach called tracing. dj vitoto online mp3I also see that sysret_check is very high. I bet if you run general exploration, then extend frontend bound/frontend latency, you'll see high % of branch resteers. If so, this is likely a performance side effects of u-code patches against Spectre attacks, that clear BTB on system calls/returns to user mode. dj vitaliano