65617710fa
A Linux module is built with -mcmodel=kernel and can only reach addresses in the top 2 GB, where this kernel is not linked. So the kernel image is mapped a second time at LDLS_KALIAS, with a vmemmap area and a module area beside it, in one PDPT shared by every address space. Nothing loads a module yet; this is the address-space groundwork, set up at every boot, and include/ldls/ is the interface the loader will use. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
53 lines
2.1 KiB
C
53 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#pragma once
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// /dev/ldls -- Linux drivers, in the kernel. docs/architecture/ldls.md.
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//
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// The device is a control channel and nothing else: a module is handed over
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// whole, as bytes, together with the BTF of the kernel it was built for, and
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// the kernel does the rest -- loading, linking, init_module, probe, and
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// bringing the interface up -- on a thread of its own. What happened comes
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// back as text, because the useful answer to "did it work" is the driver's
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// own account of what it found.
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//
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// ldls load /lib/modules/e1000.ko
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// ldls list
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// ldls unload e1000
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//
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// Shared with userland (cmd/ldls), so it is spelled in plain C types.
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#define LDLS_MAJOR 13
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// Take the device even if a kernel driver holds it, provided that driver can
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// be asked to let go. Without this LDLS only takes devices nothing else
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// drives, which is the right default at boot: the kernel's own driver is on
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// the path to a shell, and the hosted one is the better one only when someone
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// says so.
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#define LDLS_TAKE 0x1
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// Load and link, run init_module, and stop: no device is probed. For a
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// library module (mii, libphy) whose job is to export symbols to the next.
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#define LDLS_NOPROBE 0x2
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struct ldls_load {
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unsigned long long ko; // in: the module image
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unsigned long long kolen;
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unsigned long long btf; // in: the kernel's BTF, /sys/kernel/btf/vmlinux
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unsigned long long btflen;
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unsigned long long msg; // out: what happened, NUL-terminated
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unsigned int msgcap;
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unsigned int flags; // LDLS_*
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int bus, slot, func; // -1 for "whichever matches"
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unsigned int hz; // CONFIG_HZ of that kernel; 0 means 1000
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int id; // out: the module's id, for unload
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};
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struct ldls_text {
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unsigned long long buf; // out
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unsigned int cap;
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unsigned int pad;
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};
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#define LDLSIOC_LOAD 0xD000 // struct ldls_load
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#define LDLSIOC_UNLOAD 0xD001 // in: int id
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#define LDLSIOC_LIST 0xD002 // struct ldls_text
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#define LDLSIOC_LOG 0xD003 // struct ldls_text, in: pad = id
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