Differential D36189 Diff 111897 sys/dev/virtio/mmio/virtio_mmio_cmdline.c

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sys/dev/virtio/mmio/virtio_mmio_cmdline.c

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				/*-
				* Copyright (c) 2022 Colin Percival
				*
				* Redistribution and use in source and binary forms, with or without
				* modification, are permitted provided that the following conditions
				* are met:
				* 1. Redistributions of source code must retain the above copyright
				* notice, this list of conditions and the following disclaimer.
				* 2. Redistributions in binary form must reproduce the above copyright
				* notice, this list of conditions and the following disclaimer in the
				* documentation and/or other materials provided with the distribution.
				*
				* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
				* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
				* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
				* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
				* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
				* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
				* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
				* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
				* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
				* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
				* SUCH DAMAGE.
				*/

				#include <sys/param.h>
				#include <sys/systm.h>
				#include <sys/bus.h>
				#include <sys/kernel.h>
				#include <sys/limits.h>
				#include <sys/malloc.h>
				#include <sys/module.h>
				#include <sys/rman.h>

				#include <machine/bus.h>
				#include <machine/resource.h>

				#include <dev/virtio/mmio/virtio_mmio.h>

				/* Parse <size>@<baseaddr>:<irq>[:<id>] and add a child. */
				static void
				parsearg(driver_t driver, device_t parent, char arg)
				{
				jrtc27Unsubmitted Not Done Inline Actions No space (same for p below) jrtc27: No space (same for p below)
				device_t child;
				char * p;
				unsigned long sz;
				unsigned long baseaddr;
				jrtc27Unsubmitted Not Done Inline Actions Unsure if these should have better types rather than adopting the everything-is-a-long Linux-y approach (and please just call this one size) jrtc27: Unsure if these should have better types rather than adopting the everything-is-a-long Linux-y…
				cpercivaAuthorUnsubmitted Done Inline Actions I would have preferred to use `size_t` but we don't have any strtosize_t function available. Out the the types we could parse integers into, `unsigned long` seemed like the best option. cperciva: I would have preferred to use `size_t` but we don't have any strtosize_t function available.
				unsigned long irq;
				unsigned long id;

				/* <size> */
				sz = strtoul(arg, &p, 0);
				if ((sz == 0) \|\| (sz == ULONG_MAX))
				goto bad;
				switch (*p) {
				case 'E': case 'e':
				sz <<= 10;
				/* FALLTHROUGH */
				case 'P': case 'p':
				sz <<= 10;
				/* FALLTHROUGH */
				case 'T': case 't':
				sz <<= 10;
				/* FALLTHROUGH */
				case 'G': case 'g':
				sz <<= 10;
				/* FALLTHROUGH */
				case 'M': case 'm':
				sz <<= 10;
				/* FALLTHROUGH */
				case 'K': case 'k':
				sz <<= 10;
				p++;
				break;
				}

				impUnsubmitted Not Done Inline Actions Surely there's already a routine to do this stuff in the kernel.... imp: Surely there's already a routine to do this stuff in the kernel....
				cpercivaAuthorUnsubmitted Done Inline Actions I thought there would be, but I couldn't find one! I think parsing stuff like this in the kernel is far less common than printing it. cperciva: I thought there would be, but I couldn't find one! I think parsing stuff like this in the…
				/* @<baseaddr> */
				if (*p++ != '@')
				goto bad;
				baseaddr = strtoul(p, &p, 0);
				if ((baseaddr == 0) \|\| (baseaddr == ULONG_MAX))
				goto bad;
				jrtc27Unsubmitted Not Done Inline Actions ULONG_MAX is only an error if errno is ERANGE jrtc27: ULONG_MAX is only an error if errno is ERANGE
				cpercivaAuthorUnsubmitted Done Inline Actions We don't have errno in the kernel. There's no way to distinguish between an error and a "real" ULONG_MAX in libkern's strtoul... but it doesn't really matter here since a real ULONG_MAX means someone gave us nonsense anyway. cperciva: We don't have errno in the kernel. There's no way to distinguish between an error and a "real"…

				/* :<irq> */
				if (*p++ != ':')
				goto bad;
				irq = strtoul(p, &p, 0);
				if ((irq == 0) \|\| (irq == ULONG_MAX))
				goto bad;

				/* Optionally, :<id> */
				if (*p) {
				if (*p++ != ':')
				goto bad;
				id = strtoul(p, &p, 0);
				if ((id == 0) \|\| (id == ULONG_MAX))
				goto bad;
				} else {
				id = 0;
				}

				/* Should have reached the end of the string. */
				if (*p)
				goto bad;

				/* Create the child and assign its resources. */
				child = BUS_ADD_CHILD(parent, 0, driver->name, id ? id : -1);
				bus_set_resource(child, SYS_RES_MEMORY, 0, baseaddr, sz);
				jrtc27Unsubmitted Not Done Inline Actions child can be NULL. Also what happens if the same id is given twice? jrtc27: child can be NULL. Also what happens if the same id is given twice?
				impUnsubmitted Not Done Inline Actions No. child can't really be NULL. We're early enough in boot it will always succeed. imp: No. child can't really be NULL. We're early enough in boot it will always succeed.
				bus_set_resource(child, SYS_RES_IRQ, 0, irq, 1);
				device_set_driver(child, driver);
				jrtc27Unsubmitted Not Done Inline Actions This will work on x86 I believe but not on INTRNG architectures, where the IRQ IDs are virtualised and come from intr_map_irq (normally indirected via acpi/ofw_bus_map_intr). On those architectures you'd have to synthesise something and call the appropriate one for how the platform was booted. This interface is just kind of crap, there's no way to specify which interrupt controller the IRQ is for, what it's polarity is or whether it's level or edge-triggered, all things ACPI and FDT can do. I don't know what Linux does in that case, but as it stands this is horribly broken for most architectures, you'll pick up some random meaningless IRQ, if one even exists with that internal ID. jrtc27: This will work on x86 I believe but not on INTRNG architectures, where the IRQ IDs are…
				jrtc27Unsubmitted Not Done Inline Actions This still stands... ideally this would be marked broken for !INTRNG/!x86 as appropriate, otherwise you're building something that's known-broken jrtc27: This still stands... ideally this would be marked broken for !INTRNG/!x86 as appropriate…
				cpercivaAuthorUnsubmitted Done Inline Actions This still stands... ideally this would be marked broken for !INTRNG/!x86 as appropriate, otherwise you're building something that's known-broken cperciva: > This still stands... ideally this would be marked broken for !INTRNG/!x86 as appropriate…

				return;

				bad:
				printf("Error parsing virtio_mmio parameter: %s\n", arg);
				}

				static void
				vtmmio_cmdline_identify(driver_t *driver, device_t parent)
				{
				size_t n;
				char name[] = "virtio_mmio.device_XXXX";
				char * val;

				/* First variable just has its own name. */
				if ((val = kern_getenv("virtio_mmio.device")) == NULL)
				return;
				parsearg(driver, parent, val);
				freeenv(val);

				/* The rest have _%zu suffixes. */
				for (n = 1; n <= 9999; n++) {
				sprintf(name, "virtio_mmio.device_%zu", n);
				jrtc27Unsubmitted Not Done Inline Actions This is pretty sad. If they're guaranteed sequential you can avoid the upper limit. If not can you iterate over the environment instead? jrtc27: This is pretty sad. If they're guaranteed sequential you can avoid the upper limit. If not can…
				cpercivaAuthorUnsubmitted Done Inline Actions The upper limit is there to guard against buffer overflow in case someone gives us an insane kernel environment. Note that we stop scanning as soon as we find a name which isn't in the kernel environment; we (normally!) won't scan all the way up to 9999. cperciva: The upper limit is there to guard against buffer overflow in case someone gives us an insane…
				if ((val = kern_getenv(name)) == NULL)
				return;
				parsearg(driver, parent, val);
				freeenv(val);
				}
				}

				static device_method_t vtmmio_cmdline_methods[] = {
				/* Device interface. */
				DEVMETHOD(device_identify, vtmmio_cmdline_identify),
				DEVMETHOD(device_probe, vtmmio_probe),

				DEVMETHOD_END
				};
				DEFINE_CLASS_1(virtio_mmio, vtmmio_cmdline_driver, vtmmio_cmdline_methods,
				sizeof(struct vtmmio_softc), vtmmio_driver);
				DRIVER_MODULE(vtmmio_cmdline, nexus, vtmmio_cmdline_driver, 0, 0);