nemu_prepare_tls
Map the TPIDR_EL0 (thread-pointer) TLS block so its memory is accessible for pre-population via nemu_write_regions. Returns the TLS base address. Use this before writing data to TLS offsets (e.g. frame-table pointer at +0x1768) that native code reads via mrs xN, tpidr_el0; ldr xM, [xN, #large_off...
This record as markdown: /tools/io-github-vmoranv-jshookmcp/nemu-prepare-tls.md
What nemu_prepare_tls does on Jshookmcp
AI agents invoke nemu_prepare_tls to trigger actions in Jshookmcp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why nemu_prepare_tls is rated High
Maps thread-pointer memory regions enabling low-level native code memory manipulation.
From the tool's definition Map TPIDR_EL0 TLS block so its memory is accessible
Attacks that exploit this kind of access
The rule that runs nemu_prepare_tls safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For nemu_prepare_tls, this is the rule to start with:
nemu_prepare_tls stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every nemu_prepare_tls call is checked against it from then on.
Questions about nemu_prepare_tls
Map the TPIDR_EL0 (thread-pointer) TLS block so its memory is accessible for pre-population via nemu_write_regions. Returns the TLS base address. Use this before writing data to TLS offsets (e.g. frame-table pointer at +0x1768) that native code reads via mrs xN, tpidr_el0; ldr xM, [xN, #large_offset]. It is categorised as a Execute tool in the Jshookmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Jshook MCP server in PolicyLayer and add a rule for nemu_prepare_tls: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Jshookmcp. Nothing to install.
nemu_prepare_tls is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the nemu_prepare_tls rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for nemu_prepare_tls. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
nemu_prepare_tls is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Jshook, and thousands of servers like it.
Across the catalogue