Syscall swapgs

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August undefined, 2024

Websyscall logic in software Handler must save general-purpose registers as required and switch to kernel code; Tricky since %rsp is user-controlled; See syscall_entry in k … Web*PATCH 0/7] x86/entry: Convert error_entry() to C code @ 2024-05-11 7:27 Lai Jiangshan 2024-05-11 7:27 ` [PATCH 1/7] x86/entry: Introduce __entry_text for entry code written in C Lai Jiangshan ` (6 more replies) 0 siblings, 7 replies; 15+ messages in thread From: Lai Jiangshan @ 2024-05-11 7:27 UTC (permalink / raw) To: linux-kernel Cc: Borislav Petkov, …

SYSRET Shellcode Kristal’s Notebook

To facilitate using GS to store kernel data (its 'original' intention was to be used in conjunction with SYSCALL/SYSRET), a 'SWAPGS' instruction is present in long mode, which swaps the values in the KernelGSBase and GSBase Model Specific Registers. Since the processor will use the value in the GSBase MSR as the … See more In x86-64 mode, only the FS and GS registers participate in a limited form of segmentation; only their base addresses are used to calculate … See more As detailed above, Intel and AMD processors differ in their behaviour when loading a null selector into FS and GS. On AMD chips, the … See more Instead of allowing FS and GS to select a 'long' descriptor in the GDT (similar to the TSS), AMD (thankfully) created 3 new Model Specific Registers to tell the CPU what the base address of FS and GS should be. … See more A problem should start to become apparent after studying how SWAPGS behaves -- it's not nestable! For instance, if the CPU is in Ring 0 when it is interrupted, then GSBase will already contain the correct pointer; calling … See more WebTo fully understand the syscall mechanism you will need quite a bit of assembly knowledge and the endurance to investigate assembly code. And while it may seem pretty academic this chapter has practical applications: hooking the syscall table is still a thing that rootkits and antivirus solutions do. ... fffff8026858ca80 0f01f8 swapgs ... currys tumble dryers vented hotpoint

Sudden increase in CPU use by Apache, without increase in requests …

WebDealing with the swapgs instruction is especially tricky. Swapgs toggles whether gs is the kernel gs or the user gs. The swapgs instruction is rather fragile: it must nest perfectly and only in single depth, it should only be used if entering from user mode to kernel mode and then when returning to user-space, and precisely so. WebOct 30, 2024 · System Calls are used to call a kernel service from user land. The goal is to be able to switch from user mode to kernel mode, with the associated privileges. Provided … WebStudio - 3 Beds. Dog & Cat Friendly Fitness Center Dishwasher Refrigerator In Unit Washer & Dryer Clubhouse Maintenance on site CableReady. (781) 808-2562. Parkway Apartments. … charting software for stocks and options

5. Kernel Entries — The Linux Kernel documentation

SWAPGS — Swap GS Base Register - felixcloutier.com

WebSYSRET — Return From Fast System Call Instruction Operand Encoding¶ Description¶ SYSRET is a companion instruction to the SYSCALL instruction. It returns from an OS system-call handler to user code at privilege level 3. WebApr 14, 2024 · Just looking at the info perf top is currently giving me, the top two are system_call_after_swapgs, and sysret_check. Doing a bit of googling, it sounds like an increase in these could be related to Spectre mitigation? Not sure why that would have suddenly changed though, without a kernel update. Probably need that httpd perf info. – currys tv 22 inch televisionsWebMar 26, 2024 · Well, sure, but the reason you use swapgs for syscall is because you normally can't easily access the per-CPU data without modifying registers, and you don't have a stack yet. In an IRQ or exception handler, you can push registers, access the per-CPU data, and then pop them back. charting software indian stock market

"WebJun 23, 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 … " - Syscall swapgs

Syscall swapgs

Bypassing KPTI Using the Speculative Behavior of the …

WebThe CPU can speculatively do the swapgs, causing the user GS to get used for the rest of the speculative window. Spectre variant 2 ¶ A spectre variant 2 attacker can poison the … WebIn this work, we comprehensively investigate syscall filtering for PKU-based memory isolation systems. First, we identify new syscall-based attacks that can break a PKU …

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WebNov 25, 2024 · Как только этот бюджет превышен, пробуждается отдельный поток ksoftirqd (вы увидите один из них в ps для каждого ядра), который обрабатывает эти softirq за пределами обычного пути syscall/interrupt. Этот ... WebThe rest of the code is similar to the SYSCALL handler. Another interesting gadget is the following: f60596a1390001 test byte ptr [nt!KiKvaShadow],1 7503 jne skip_swapgs 0f01f8 swapgs 654c8b142588010000 mov r10,qword ptr gs:[188h] 65488b0c2588010000 mov rcx,qword ptr gs:[188h]

WebAug 7, 2024 · I am wondering, is there a syscall, or has this ever been discussed, to move memory pages from swap back to RAM, given there is enough free RAM? I am thinking of … Webswapgs iretq "), sp = const (offset_of! (gdt::ProcessorControlRegion, user_rsp_tmp)), ksp = const (offset_of! (gdt::ProcessorControlRegion, tss) + offset_of! (TaskStateSegment, rsp)), ss_sel = const (SegmentSelector::new (gdt::GDT_USER_DATA as u16, x86::Ring::Ring3).bits ()),

Web🐛 Describe the bug Not sure if this is intentional but a DataLoader does not accept a non-cpu device despite tensors living somewhere else. Example of a few months of a big issue that allows you to pass in cuda Generator to the dataloade... WebOct 30, 2024 · System Calls are used to call a kernel service from user land. The goal is to be able to switch from user mode to kernel mode, with the associated privileges. Provided system calls depend on the nature of your kernel . Contents [ hide ] 1 Possible methods to make a System Call 1.1 Interrupts 1.2 Sysenter/Sysexit (Intel) 1.3 Trap

WebAug 7, 2024 · To facilitate using GS to store kernel data (its 'original' intention was to be used in conjunction with SYSCALL/SYSRET), a 'SWAPGS' instruction is present in long mode, which swaps the values in the KernelGSBase and GSBase Model Specific Registers. Since the processor will use the value in the GSBase MSR as the base address of GS, …

WebRINO'S PLACE 258 Saratoga St. Boston, MA 02128 Phone: 617-567-7412: ITALIAN EXPRESS PIZZERIA 336 Sumner St. East Boston, MA 02128 Phone: 617-561-0038 charting spaceWebThe syscall and sysenter instructions have their own peculiar calling conventions. Some of the IDT entries push an error code onto the stack; others don’t. IDT entries using the IST … currys tumble dryers vented hooverWebاستخدم تعليمات syscall لتشغيل مكالمة النظام. يتم تبديل وحدة المعالجة المركزية من وضع المستخدم (RING3) إلى الامتياز (RING0) ، ويتم استخدام تعليمات SYSRET للتبديل من حالة kernel إلى حالة المستخدم. currys tumble dryer vented hotpointWebA spectre variant 2 attacker can poison the branch target buffer (BTB) before issuing syscall to launch an attack. After entering the kernel, the kernel could use the poisoned branch target buffer on indirect jump and jump to gadget code in speculative execution. ... The swapgs protections are disabled; otherwise it has protection in the kernel ... currys tv 24 inchWebAug 27, 2024 · Sys_exit_group+0x10/0x10 ..... ? do_syscall_64+0x8d/0x100 ..... ? entry_SYSCALL_64_after_swapgs+0x58/0xc6 .... Kernel Offset: 0x27800000 from … currys tv 28 inchWebSep 28, 2024 · The likely reason for encountering an ILL (illegal instruction) signal is that your CPU does not meet the x86_64 microarchitecture requirements for the version of MongoDB server you are trying to install. Regards, Stennie davip (Davip) September 15, … currys tv 39 inchWebJan 25, 2024 · Lower 32 bits = SYSCALL EIP, bits 32-47 are the kernel segment base, and bits 48-63 are the user segment base. IA32_CSTAR (0xC0000083) - The kernel's RIP for SYSCALL in compatibility mode. ... First, SWAPGS is used to exchange the current GS base register value with the value contained in MSR address C0000102H … chartingspace.com