MFC r283407:

Implement vdso - virtual dynamic shared object. Through vdso Linux
exposes functions from kernel with proper DWARF CFI information so that
it becomes easier to unwind through them.
Using vdso is a mandatory for a thread cancelation && cleanup
on a modern glibc.

3 files changed, 307 insertions, 0 deletions

diff --git a/sys/compat/linux/linux_misc.h b/sys/compat/linux/linux_misc.h
index 454e92d..1623422 100644
--- a/sys/compat/linux/linux_misc.h
+++ b/sys/compat/linux/linux_misc.h
@@ -69,6 +69,8 @@ extern const char *linux_platform;
 					 * differ from AT_PLATFORM.
 					 */
 #define	LINUX_AT_EXECFN		31	/* filename of program */
+#define	LINUX_AT_SYSINFO	32	/* vsyscall */
+#define	LINUX_AT_SYSINFO_EHDR	33	/* vdso header */
 
 /* Linux sets the i387 to extended precision. */
 #if defined(__i386__) || defined(__amd64__)
diff --git a/sys/compat/linux/linux_vdso.c b/sys/compat/linux/linux_vdso.c
new file mode 100644
index 0000000..871a5da
--- /dev/null
+++ b/sys/compat/linux/linux_vdso.c
@@ -0,0 +1,240 @@
+/*-
+ * Copyright (c) 2013 Dmitry Chagin
+ * 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
+ *    in this position and unchanged.
+ * 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 ``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 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>
+__FBSDID("$FreeBSD$");
+
+#include "opt_compat.h"
+
+#define	__ELF_WORD_SIZE	32
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/elf.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/rwlock.h>
+#include <sys/queue.h>
+#include <sys/sysent.h>
+
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/pmap.h>
+#include <vm/vm_extern.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_map.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_pager.h>
+
+#include <compat/linux/linux_vdso.h>
+
+SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
+    SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
+
+static int __elfN(symtabindex);
+static int __elfN(symstrindex);
+
+static void
+__elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *);
+
+
+void
+__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
+{
+
+	SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
+}
+
+vm_object_t
+__elfN(linux_shared_page_init)(char **mapping)
+{
+	vm_page_t m;
+	vm_object_t obj;
+	vm_offset_t addr;
+
+	obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
+	    VM_PROT_DEFAULT, 0, NULL);
+	VM_OBJECT_WLOCK(obj);
+	m = vm_page_grab(obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
+	m->valid = VM_PAGE_BITS_ALL;
+	VM_OBJECT_WUNLOCK(obj);
+	addr = kva_alloc(PAGE_SIZE);
+	pmap_qenter(addr, &m, 1);
+	*mapping = (char *)addr;
+	return (obj);
+}
+
+void
+__elfN(linux_shared_page_fini)(vm_object_t obj)
+{
+
+	vm_object_deallocate(obj);
+}
+
+void
+__elfN(linux_vdso_fixup)(struct sysentvec *sv)
+{
+	Elf_Ehdr *ehdr;
+	Elf_Shdr *shdr;
+	int i;
+
+	ehdr = (Elf_Ehdr *) sv->sv_sigcode;
+
+	if (!IS_ELF(*ehdr) ||
+	    ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
+	    ehdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
+	    ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
+	    ehdr->e_shoff == 0 ||
+	    ehdr->e_shentsize != sizeof(Elf_Shdr))
+		panic("Linux invalid vdso header.\n");
+
+	if (ehdr->e_type != ET_DYN)
+		panic("Linux invalid vdso header.\n");
+
+	shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
+
+	__elfN(symtabindex) = -1;
+	__elfN(symstrindex) = -1;
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		if (shdr[i].sh_size == 0)
+			continue;
+		if (shdr[i].sh_type == SHT_DYNSYM) {
+			__elfN(symtabindex) = i;
+			__elfN(symstrindex) = shdr[i].sh_link;
+		}
+	}
+
+	if (__elfN(symtabindex) == -1 || __elfN(symstrindex) == -1)
+		panic("Linux invalid vdso header.\n");
+
+	ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;
+}
+
+void
+__elfN(linux_vdso_reloc)(struct sysentvec *sv, int vdso_adjust)
+{
+	struct linux_vdso_sym *lsym;
+	Elf_Ehdr *ehdr;
+	Elf_Phdr *phdr;
+	Elf_Shdr *shdr;
+	Elf_Dyn *dyn;
+	Elf_Sym *sym;
+	int i, symcnt;
+
+	ehdr = (Elf_Ehdr *) sv->sv_sigcode;
+
+	/* Adjust our so relative to the sigcode_base */
+	if (vdso_adjust != 0) {
+		ehdr->e_entry += vdso_adjust;
+		phdr = (Elf_Phdr *)((caddr_t)ehdr + ehdr->e_phoff);
+
+		/* phdrs */
+		for (i = 0; i < ehdr->e_phnum; i++) {
+			phdr[i].p_vaddr += vdso_adjust;
+			if (phdr[i].p_type != PT_DYNAMIC)
+				continue;
+			dyn = (Elf_Dyn *)((caddr_t)ehdr + phdr[i].p_offset);
+			for(; dyn->d_tag != DT_NULL; dyn++) {
+				switch (dyn->d_tag) {
+				case DT_PLTGOT:
+				case DT_HASH:
+				case DT_STRTAB:
+				case DT_SYMTAB:
+				case DT_RELA:
+				case DT_INIT:
+				case DT_FINI:
+				case DT_REL:
+				case DT_DEBUG:
+				case DT_JMPREL:
+				case DT_VERSYM:
+				case DT_VERDEF:
+				case DT_VERNEED:
+				case DT_ADDRRNGLO ... DT_ADDRRNGHI:
+					dyn->d_un.d_ptr += vdso_adjust;
+					break;
+				case DT_ENCODING ... DT_LOOS-1:
+				case DT_LOOS ... DT_HIOS:
+					if (dyn->d_tag >= DT_ENCODING &&
+					    (dyn->d_tag & 1) == 0)
+						dyn->d_un.d_ptr += vdso_adjust;
+					break;
+				default:
+					break;
+				}
+			}
+		}
+
+		/* sections */
+		shdr = (Elf_Shdr *)((caddr_t)ehdr + ehdr->e_shoff);
+		for(i = 0; i < ehdr->e_shnum; i++) {
+			if (!(shdr[i].sh_flags & SHF_ALLOC))
+				continue;
+			shdr[i].sh_addr += vdso_adjust;
+			if (shdr[i].sh_type != SHT_SYMTAB &&
+			    shdr[i].sh_type != SHT_DYNSYM)
+				continue;
+
+			sym = (Elf_Sym *)((caddr_t)ehdr + shdr[i].sh_offset);
+			symcnt = shdr[i].sh_size / sizeof(*sym);
+
+			for(i = 0; i < symcnt; i++, sym++) {
+				if (sym->st_shndx == SHN_UNDEF ||
+				    sym->st_shndx == SHN_ABS)
+					continue;
+				sym->st_value += vdso_adjust;
+			}
+		}
+	}
+
+	SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym)
+		__elfN(linux_vdso_lookup)(ehdr, lsym);
+}
+
+static void
+__elfN(linux_vdso_lookup)(Elf_Ehdr *ehdr, struct linux_vdso_sym *vsym)
+{
+	vm_offset_t strtab, symname;
+	uint32_t symcnt;
+	Elf_Shdr *shdr;
+	int i;
+
+	shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
+
+	strtab = (vm_offset_t)((caddr_t)ehdr +
+	    shdr[__elfN(symstrindex)].sh_offset);
+	Elf_Sym *sym = (Elf_Sym *)((caddr_t)ehdr +
+	    shdr[__elfN(symtabindex)].sh_offset);
+	symcnt = shdr[__elfN(symtabindex)].sh_size / sizeof(*sym);
+
+	for (i = 0; i < symcnt; ++i, ++sym) {
+		symname = strtab + sym->st_name;
+		if (strncmp(vsym->symname, (char *)symname, vsym->size) == 0) {
+			*vsym->ptr = (uintptr_t)sym->st_value;
+			break;
+		}
+	}
+}
diff --git a/sys/compat/linux/linux_vdso.h b/sys/compat/linux/linux_vdso.h
new file mode 100644
index 0000000..a3ee63d
--- /dev/null
+++ b/sys/compat/linux/linux_vdso.h
@@ -0,0 +1,65 @@
+/*-
+ * Copyright (c) 2013 Dmitry Chagin
+ * 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
+ *    in this position and unchanged.
+ * 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 ``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 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _LINUX_VDSO_H_
+#define	_LINUX_VDSO_H_
+
+#include <sys/types.h>
+
+struct linux_vdso_sym {
+	SLIST_ENTRY(linux_vdso_sym) sym;
+	uint32_t	size;
+	uintptr_t *	ptr;
+	char		symname[];
+};
+
+vm_object_t __elfN(linux_shared_page_init)(char **);
+void	__elfN(linux_shared_page_fini)(vm_object_t);
+void	__elfN(linux_vdso_fixup)(struct sysentvec *);
+void	__elfN(linux_vdso_reloc)(struct sysentvec *, int);
+void	__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *);
+
+#define	LINUX_VDSO_SYM_INTPTR(name)				\
+uintptr_t name;							\
+LINUX_VDSO_SYM_DEFINE(name)
+
+#define	LINUX_VDSO_SYM_CHAR(name)				\
+const char * name;						\
+LINUX_VDSO_SYM_DEFINE(name)
+
+#define	LINUX_VDSO_SYM_DEFINE(name)				\
+static struct linux_vdso_sym name ## sym = {			\
+	.symname	= #name,				\
+	.size		= sizeof(#name),			\
+	.ptr		= (uintptr_t *)&name			\
+};								\
+SYSINIT(__elfN(name ## _sym_init), SI_SUB_EXEC,			\
+    SI_ORDER_FIRST, __elfN(linux_vdso_sym_init), &name ## sym);	\
+struct __hack
+
+#endif	/* _LINUX_VDSO_H_ */