xref: /src/sys/dev/kloader.c

/*	$NetBSD: kloader.c,v 1.32 2021/10/11 14:25:05 rin Exp $	*/

/*-
 * Copyright (c) 2001, 2002, 2004 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kloader.c,v 1.32 2021/10/11 14:25:05 rin Exp $");

#include "debug_kloader.h"

#include <sys/param.h>
#include <sys/fcntl.h>
#include <sys/kmem.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/vnode.h>

#define	ELFSIZE	32
#include <sys/exec_elf.h>

#include <uvm/uvm_extern.h>

#include <machine/kloader.h>

#define	PRINTF(fmt, args...)	printf("kloader: " fmt, ##args)

#ifdef KLOADER_DEBUG
int	kloader_debug = 1;
#define	DPRINTF(fmt, args...)						\
	if (kloader_debug)						\
		printf("%s: " fmt, __func__ , ##args)
#define	_DPRINTF(fmt, args...)						\
	if (kloader_debug)						\
		printf(fmt, ##args)
#define	DPRINTFN(n, fmt, args...)					\
	if (kloader_debug > (n))					\
		printf("%s: " fmt, __func__ , ##args)
#define	_DPRINTFN(n, fmt, args...)					\
	if (kloader_debug > (n))					\
		printf(fmt, ##args)
#define	STATIC
#else
#define	DPRINTF(fmt, args...)		((void)0)
#define	_DPRINTF(fmt, args...)		((void)0)
#define	DPRINTFN(n, fmt, args...)	((void)0)
#define	_DPRINTFN(n, fmt, args...)	((void)0)
#define	STATIC	static
#endif

struct kloader {
	struct pglist pg_head;
	struct vm_page *cur_pg;		/* XXX use bus_dma(9) */
	struct kloader_page_tag *cur_tag;
	struct vnode *vp;
	struct kloader_page_tag *tagstart;
	struct kloader_bootinfo *bootinfo;
	struct kloader_bootinfo *rebootinfo;
	vaddr_t loader_sp;
	kloader_bootfunc_t *loader;
	int setuped;
	int called;
	struct kloader_ops *ops;
};

#define	BUCKET_SIZE	(PAGE_SIZE - sizeof(struct kloader_page_tag))
#define	KLOADER_LWP	(&lwp0)
STATIC struct kloader kloader;

#define	ROUND4(x)	(((x) + 3) & ~3)

STATIC int kloader_load(void);

STATIC int kloader_alloc_memory(size_t);
STATIC struct kloader_page_tag *kloader_get_tag(vaddr_t);
STATIC void kloader_from_file(vaddr_t, off_t, size_t);
STATIC void kloader_copy(vaddr_t, const void *, size_t);
STATIC void kloader_zero(vaddr_t, size_t);

STATIC void kloader_load_segment(Elf_Phdr *);

STATIC struct vnode *kloader_open(const char *);
STATIC void kloader_close(void);
STATIC int kloader_read(size_t, size_t, void *);

#ifdef KLOADER_DEBUG
STATIC void kloader_pagetag_dump(void);
#endif

void
__kloader_reboot_setup(struct kloader_ops *ops, const char *filename)
{

	if (kloader.bootinfo == NULL) {
		PRINTF("No bootinfo.\n");
		return;
	}

	if (ops == NULL || ops->jump == NULL || ops->boot == NULL) {
		PRINTF("No boot operations.\n");
		return;
	}
	kloader.ops = ops;

	if (kloader.called++ == 0) {
		PRINTF("kernel file name: %s\n", filename);
		kloader.vp = kloader_open(filename);
		if (kloader.vp == NULL)
			return;

		if (kloader_load() == 0) {
			kloader.setuped = TRUE;
#ifdef KLOADER_DEBUG
			kloader_pagetag_dump();
#endif
		}
		kloader_close();
	} else {
		/* Fatal case. reboot from DDB etc. */
		kloader_reboot();
	}
}


void
kloader_reboot(void)
{

	if (kloader.setuped) {
		PRINTF("Rebooting...\n");
		(*kloader.ops->jump)(kloader.loader, kloader.loader_sp,
		    kloader.rebootinfo, kloader.tagstart);
	}

	if (kloader.ops->reset != NULL) {
		PRINTF("Resetting...\n");
		(*kloader.ops->reset)();
	}
	while (/*CONSTCOND*/1)
		continue;
	/* NOTREACHED */
}


int
kloader_load(void)
{
	Elf_Ehdr eh;
	Elf_Phdr *ph, *p;
	Elf_Shdr *sh;
	Elf_Addr entry;
	vaddr_t kv;
	size_t sz;
	size_t phsz, shsz, shstrsz;
	char *shstrtab;
	int symndx, strndx;
	size_t ksymsz;
	struct kloader_bootinfo nbi; /* new boot info */
	char *oldbuf, *newbuf;
	char **ap;
	int i;

	ph = NULL;
	sh = NULL;
	shstrtab = NULL;

	/* read kernel's ELF header */
	kloader_read(0, sizeof(Elf_Ehdr), &eh);

	if (eh.e_ident[EI_MAG0] != ELFMAG0 ||
	    eh.e_ident[EI_MAG1] != ELFMAG1 ||
	    eh.e_ident[EI_MAG2] != ELFMAG2 ||
	    eh.e_ident[EI_MAG3] != ELFMAG3) {
		PRINTF("not an ELF file\n");
		goto err;
	}

	/* read program headers */
	phsz = eh.e_phentsize * eh.e_phnum;
	if ((ph = kmem_alloc(phsz, KM_NOSLEEP)) == NULL) {
		PRINTF("can't allocate program header table.\n");
		goto err;
	}
	if (kloader_read(eh.e_phoff, phsz, ph) != 0) {
		PRINTF("program header read error.\n");
		goto err;
	}

	/* read section headers */
	shsz = eh.e_shentsize * eh.e_shnum;
	if ((sh = kmem_alloc(shsz, KM_NOSLEEP)) == NULL) {
		PRINTF("can't allocate section header table.\n");
		goto err;
	}
	if (kloader_read(eh.e_shoff, shsz, sh) != 0) {
		PRINTF("section header read error.\n");
		goto err;
	}

	/* read section names */
	shstrsz = ROUND4(sh[eh.e_shstrndx].sh_size);
	shstrtab = kmem_alloc(shstrsz, KM_NOSLEEP);
	if (shstrtab == NULL) {
		PRINTF("unable to allocate memory for .shstrtab\n");
		goto err;
	}
	DPRINTF("reading 0x%x bytes of .shstrtab at 0x%x\n",
	    sh[eh.e_shstrndx].sh_size, sh[eh.e_shstrndx].sh_offset);
	kloader_read(sh[eh.e_shstrndx].sh_offset, sh[eh.e_shstrndx].sh_size,
	    shstrtab);

	/* save entry point, code to construct symbol table overwrites it */
	entry = eh.e_entry;

	/*
	 * Calculate memory size
	 */
	sz = 0;

	/* loadable segments */
	for (i = 0; i < eh.e_phnum; i++) {
		if (ph[i].p_type == PT_LOAD) {
			DPRINTF("segment %d size = file 0x%x memory 0x%x\n",
			    i, ph[i].p_filesz, ph[i].p_memsz);
#ifdef KLOADER_ZERO_BSS
			sz += round_page(ph[i].p_memsz);
#else
			sz += round_page(ph[i].p_filesz);
#endif
			sz += PAGE_SIZE; /* compensate for partial last tag */
		}
	}

	if (sz == 0)		/* nothing to load? */
		goto err;

	/* symbols/strings sections */
	symndx = strndx = -1;
	for (i = 0; i < eh.e_shnum; i++) {
		if (strcmp(shstrtab + sh[i].sh_name, ".symtab") == 0)
			symndx = i;
		else if (strcmp(shstrtab + sh[i].sh_name, ".strtab") == 0)
			strndx = i;
		else if (i != eh.e_shstrndx) {
			/* while here, mark all other sections as unused */
			sh[i].sh_type = SHT_NULL;
			sh[i].sh_offset = 0;
		}
	}

	if (symndx < 0 || strndx < 0) {
		if (symndx < 0)
			PRINTF("no .symtab section\n");
		if (strndx < 0)
			PRINTF("no .strtab section\n");
		ksymsz = SELFMAG; /* just a bad magic */
	} else {
		ksymsz = sizeof(Elf_Ehdr)
		    + eh.e_shentsize * eh.e_shnum
		    + shstrsz		/* rounded to 4 bytes */
		    + sh[symndx].sh_size
		    + sh[strndx].sh_size;
		DPRINTF("ksyms size = 0x%zx\n", ksymsz);
	}
	sz += ROUND4(ksymsz);

	/* boot info for the new kernel */
	sz += sizeof(struct kloader_bootinfo);

	/* get memory for new kernel */
	if (kloader_alloc_memory(sz) != 0)
		goto err;

	/*
	 * Copy new kernel in.
	 */
	kv = 0;			/* XXX: -Wuninitialized */
	for (i = 0, p = ph; i < eh.e_phnum; i++, p++) {
		if (p->p_type == PT_LOAD) {
			kloader_load_segment(p);
			kv = p->p_vaddr + ROUND4(p->p_memsz);
		}
	}

	/*
	 * Construct symbol table for ksyms.
	 */
	if (symndx < 0 || strndx < 0) {
		kloader_zero(kv, SELFMAG);
		kv += SELFMAG;
	} else {
		Elf_Off eoff;
		off_t symoff, stroff;

		/* save offsets of .symtab and .strtab before we change them */
		symoff = sh[symndx].sh_offset;
		stroff = sh[strndx].sh_offset;

		/* no loadable segments */
		eh.e_entry = 0;
		eh.e_phnum = 0;
		eh.e_phoff = 0;

		/* change offsets to reflect new layout */
		eoff = sizeof(Elf_Ehdr);
		eh.e_shoff = eoff;

		eoff += eh.e_shentsize * eh.e_shnum;
		sh[eh.e_shstrndx].sh_offset = eoff;

		eoff += shstrsz;
		sh[symndx].sh_offset = eoff;

		eoff += sh[symndx].sh_size;
		sh[strndx].sh_offset = eoff;

		/* local copies massaged, can serve them now */
		DPRINTF("ksyms ELF header\n");
		kloader_copy(kv, &eh, sizeof(Elf_Ehdr));
		kv += sizeof(Elf_Ehdr);

		DPRINTF("ksyms section headers\n");
		kloader_copy(kv, sh, eh.e_shentsize * eh.e_shnum);
		kv += eh.e_shentsize * eh.e_shnum;

		DPRINTF("ksyms .shstrtab\n");
		kloader_copy(kv, shstrtab, shstrsz);
		kv += shstrsz;

		DPRINTF("ksyms .symtab\n");
		kloader_from_file(kv, symoff, sh[symndx].sh_size);
		kv += sh[symndx].sh_size;

		DPRINTF("ksyms .strtab\n");
		kloader_from_file(kv, stroff, ROUND4(sh[strndx].sh_size));
		kv += ROUND4(sh[strndx].sh_size);
	}

	/*
	 * Create boot info to pass to the new kernel.
	 * All pointers in it are *not* valid until the new kernel runs!
	 */

	/* get a private copy of current bootinfo to vivisect */
	memcpy(&nbi, kloader.bootinfo, sizeof(struct kloader_bootinfo));

	/* new kernel entry point */
	nbi.entry = entry;

	/* where args currently are, see kloader_bootinfo_set() */
	oldbuf = &kloader.bootinfo->_argbuf[0];

	/* where args *will* be after boot code copied them */
	newbuf = (char *)(void *)kv
	    + offsetof(struct kloader_bootinfo, _argbuf);

	DPRINTF("argv: old %p -> new %p\n", oldbuf, newbuf);

	/* not a valid pointer in this kernel! */
	nbi.argv = (void *)newbuf;

	/* local copy that we populate with new (not yet valid) pointers */
	ap = (char **)(void *)nbi._argbuf;

	for (i = 0; i < kloader.bootinfo->argc; ++i) {
		DPRINTFN(1, " [%d]: %p -> ", i, kloader.bootinfo->argv[i]);
		ap[i] = newbuf +
		    (kloader.bootinfo->argv[i] - oldbuf);
		_DPRINTFN(1, "%p\n", ap[i]);
	}

	/* arrange for the new bootinfo to get copied */
	DPRINTF("bootinfo\n");
	kloader_copy(kv, &nbi, sizeof(struct kloader_bootinfo));

	/* will be valid by the time the new kernel starts */
	kloader.rebootinfo = (void *)kv;
	/* kv += sizeof(struct kloader_bootinfo); */

	/*
	 * Copy loader code
	 */
	KDASSERT(kloader.cur_pg);
	kloader.loader = (void *)PG_VADDR(kloader.cur_pg);
	memcpy(kloader.loader, kloader.ops->boot, PAGE_SIZE);

	/* loader stack starts at the bottom of that page */
	kloader.loader_sp = (vaddr_t)kloader.loader + PAGE_SIZE;

	DPRINTF("[loader] addr=%p sp=%p [kernel] entry=%p\n",
	    kloader.loader, (void *)kloader.loader_sp, (void *)nbi.entry);

	return (0);
 err:
	if (ph != NULL)
		kmem_free(ph, phsz);
	if (sh != NULL)
		kmem_free(sh, shsz);
	if (shstrtab != NULL)
		kmem_free(shstrtab, shstrsz);

	return 1;
}


int
kloader_alloc_memory(size_t sz)
{
	int n, error;

	n = (sz + BUCKET_SIZE - 1) / BUCKET_SIZE	/* kernel &co */
	    + 1;					/* 2nd loader */

	error = uvm_pglistalloc(n * PAGE_SIZE, avail_start, avail_end,
	    PAGE_SIZE, 0, &kloader.pg_head, n, 0);
	if (error) {
		PRINTF("can't allocate memory.\n");
		return (1);
	}
	DPRINTF("allocated %d pages.\n", n);

	kloader.cur_pg = TAILQ_FIRST(&kloader.pg_head);
	kloader.tagstart = (void *)PG_VADDR(kloader.cur_pg);
	kloader.cur_tag = NULL;

	return (0);
}


struct kloader_page_tag *
kloader_get_tag(vaddr_t dst)
{
	struct vm_page *pg;
	vaddr_t addr;
	struct kloader_page_tag *tag;

	tag = kloader.cur_tag;
	if (tag != NULL		/* has tag */
	    && tag->sz < BUCKET_SIZE /* that has free space */
	    && tag->dst + tag->sz == dst) /* and new data are contiguous */
	{
		DPRINTFN(1, "current tag %x/%x ok\n", tag->dst, tag->sz);
		return (tag);
	}

	pg = kloader.cur_pg;
	KDASSERT(pg != NULL);
	kloader.cur_pg = TAILQ_NEXT(pg, pageq.queue);

	addr = PG_VADDR(pg);
	tag = (void *)addr;

	/*
	 * 2nd loader uses simple word-by-word copy, so destination
	 * address of a tag must be properly aligned.
	 */
	KASSERT(ALIGNED_POINTER(dst, register_t));

	tag->src = addr + sizeof(struct kloader_page_tag);
	tag->dst = dst;
	tag->sz = 0;
	tag->next = 0;	/* Terminate. this member may overwrite after. */
	if (kloader.cur_tag)
		kloader.cur_tag->next = addr;
	kloader.cur_tag = tag;

	return (tag);
}


/*
 * Operations to populate kloader_page_tag's with data.
 */

void
kloader_from_file(vaddr_t dst, off_t ofs, size_t sz)
{
	struct kloader_page_tag *tag;
	size_t freesz;

	while (sz > 0) {
		tag = kloader_get_tag(dst);
		KDASSERT(tag != NULL);
		freesz = BUCKET_SIZE - tag->sz;
		if (freesz > sz)
			freesz = sz;

		DPRINTFN(1, "0x%08"PRIxVADDR" + 0x%zx <- 0x%lx\n", dst, freesz,
		    (unsigned long)ofs);
		kloader_read(ofs, freesz, (void *)(tag->src + tag->sz));

		tag->sz += freesz;
		sz -= freesz;
		ofs += freesz;
		dst += freesz;
	}
}


void
kloader_copy(vaddr_t dst, const void *src, size_t sz)
{
	struct kloader_page_tag *tag;
	size_t freesz;

	while (sz > 0) {
		tag = kloader_get_tag(dst);
		KDASSERT(tag != NULL);
		freesz = BUCKET_SIZE - tag->sz;
		if (freesz > sz)
			freesz = sz;

		DPRINTFN(1, "0x%08"PRIxVADDR" + 0x%zx <- %p\n", dst, freesz, src);
		memcpy((void *)(tag->src + tag->sz), src, freesz);

		tag->sz += freesz;
		sz -= freesz;
		src = (const char *)src + freesz;
		dst += freesz;
	}
}


void
kloader_zero(vaddr_t dst, size_t sz)
{
	struct kloader_page_tag *tag;
	size_t freesz;

	while (sz > 0) {
		tag = kloader_get_tag(dst);
		KDASSERT(tag != NULL);
		freesz = BUCKET_SIZE - tag->sz;
		if (freesz > sz)
			freesz = sz;

		DPRINTFN(1, "0x%08"PRIxVADDR" + 0x%zx\n", dst, freesz);
		memset((void *)(tag->src + tag->sz), 0, freesz);

		tag->sz += freesz;
		sz -= freesz;
		dst += freesz;
	}
}


void
kloader_load_segment(Elf_Phdr *p)
{

	DPRINTF("memory 0x%08x 0x%x <- file 0x%x 0x%x\n",
	    p->p_vaddr, p->p_memsz, p->p_offset, p->p_filesz);

	kloader_from_file(p->p_vaddr, p->p_offset, p->p_filesz);
#ifdef KLOADER_ZERO_BSS
	kloader_zero(p->p_vaddr + p->p_filesz, p->p_memsz - p->p_filesz);
#endif
}


/*
 * file access
 */
struct vnode *
kloader_open(const char *filename)
{
	struct pathbuf *pb;
	struct nameidata nid;
	struct vnode *vp;
	int error;

	pb = pathbuf_create(filename);
	if (pb == NULL) {
		PRINTF("%s: pathbuf_create failed\n", filename);
		return (NULL);
	}

	/*
	 * XXX why does this call both namei and vn_open?
	 */

	NDINIT(&nid, LOOKUP, FOLLOW, pb);
	error = namei(&nid);
	if (error != 0) {
		PRINTF("%s: namei failed, errno=%d\n", filename, error);
		pathbuf_destroy(pb);
		return (NULL);
	}

	error = vn_open(NULL, pb, 0, FREAD, 0, &vp, NULL, NULL);
	if (error != 0) {
		PRINTF("%s: open failed, errno=%d\n", filename, error);
		pathbuf_destroy(pb);
		return (NULL);
	}

	pathbuf_destroy(pb);
	return vp;
}

void
kloader_close(void)
{
	struct lwp *l = KLOADER_LWP;
	struct vnode *vp = kloader.vp;

	VOP_UNLOCK(vp);
	vn_close(vp, FREAD, l->l_cred);
}

int
kloader_read(size_t ofs, size_t size, void *buf)
{
	struct lwp *l = KLOADER_LWP;
	struct vnode *vp = kloader.vp;
	size_t resid;
	int error;

	error = vn_rdwr(UIO_READ, vp, buf, size, ofs, UIO_SYSSPACE,
	    IO_NODELOCKED | IO_SYNC, l->l_cred, &resid, NULL);

	if (error)
		PRINTF("read error.\n");

	return (error);
}


/*
 * bootinfo
 */
void
kloader_bootinfo_set(struct kloader_bootinfo *kbi, int argc, char *argv[],
    struct bootinfo *bi, int printok)
{
	char *p, *pend, *buf;
	int i;

	kloader.bootinfo = kbi;
	buf = kbi->_argbuf;
	if (bi != NULL)
		memcpy(&kbi->bootinfo, bi, sizeof(struct bootinfo));
	kbi->argc = argc;
	kbi->argv = (char **)buf;

	p = &buf[argc * sizeof(char **)];
	pend = &buf[KLOADER_KERNELARGS_MAX - 1];

	for (i = 0; i < argc; i++) {
		char *q = argv[i];
		int len = strlen(q) + 1;
		if ((p + len) > pend) {
			kloader.bootinfo = NULL;
			if (printok)
				PRINTF("buffer insufficient.\n");
			return;
		}
		kbi->argv[i] = p;
		memcpy(p, q, len);
		p += len;
	}
}


#ifdef KLOADER_DEBUG
void
kloader_pagetag_dump(void)
{
	struct kloader_page_tag *tag = kloader.tagstart;
	struct kloader_page_tag *p, *op;
	bool print;
	int i, n;

	p = tag;
	op = NULL;
	i = 0, n = 15;

	PRINTF("[page tag chain]\n");
	do  {
		print = FALSE;
		if (i < n)
			print = TRUE;
		if ((uint32_t)p & 3) {
			printf("tag alignment error\n");
			break;
		}
		if ((p->src & 3) || (p->dst & 3)) {
			printf("data alignment error.\n");
			print = TRUE;
		}

		if (print) {
			printf("[%2d] next 0x%08x src 0x%08x dst 0x%08x"
			    " sz 0x%x\n", i, p->next, p->src, p->dst, p->sz);
		} else if (i == n) {
			printf("[...]\n");
		}
		op = p;
		i++;
	} while ((p = (struct kloader_page_tag *)(p->next)) != 0);

	if (op != NULL)
		printf("[%d(last)] next 0x%08x src 0x%08x dst 0x%08x sz 0x%x\n",
		    i - 1, op->next, op->src, op->dst, op->sz);
}

#endif /* KLOADER_DEBUG */