Add support for executing the FreeBSD 1/i386 a.out binaries on amd64.

In particular:
- implement compat shims for old stat(2) variants and ogetdirentries(2);
- implement delivery of signals with ancient stack frame layout and
  corresponding sigreturn(2);
- implement old getpagesize(2);
- provide a user-mode trampoline and LDT call gate for lcall $7,$0;
- port a.out image activator and connect it to the build as a module
  on amd64.

The changes are hidden under COMPAT_43.

MFC after:   1 month

1 files changed, 69 insertions, 14 deletions

diff --git a/sys/kern/imgact_aout.c b/sys/kern/imgact_aout.c
index a783c41..2f168d8 100644
--- a/sys/kern/imgact_aout.c
+++ b/sys/kern/imgact_aout.c
@@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/imgact.h>
 #include <sys/imgact_aout.h>
 #include <sys/kernel.h>
+#include <sys/limits.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/mutex.h>
@@ -52,9 +53,18 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_object.h>
 #include <vm/vm_param.h>
 
+#ifdef __amd64__
+#include <compat/freebsd32/freebsd32_signal.h>
+#include <compat/freebsd32/freebsd32_util.h>
+#include <compat/freebsd32/freebsd32_proto.h>
+#include <compat/freebsd32/freebsd32_syscall.h>
+#include <compat/ia32/ia32_signal.h>
+#endif
+
 static int	exec_aout_imgact(struct image_params *imgp);
 static int	aout_fixup(register_t **stack_base, struct image_params *imgp);
 
+#if defined(__i386__)
 struct sysentvec aout_sysvec = {
 	.sv_size	= SYS_MAXSYSCALL,
 	.sv_table	= sysent,
@@ -83,31 +93,69 @@ struct sysentvec aout_sysvec = {
 	.sv_setregs	= exec_setregs,
 	.sv_fixlimit	= NULL,
 	.sv_maxssiz	= NULL,
-	.sv_flags	= SV_ABI_FREEBSD | SV_AOUT |
-#if defined(__i386__)
-	SV_IA32 | SV_ILP32
-#else
-#error Choose SV_XXX flags for the platform
-#endif
-	,
+	.sv_flags	= SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = cpu_fetch_syscall_args,
 	.sv_syscallnames = syscallnames,
 	.sv_schedtail	= NULL,
 };
 
+#elif defined(__amd64__)
+
+#define	AOUT32_USRSTACK	0xbfc0000
+#define	AOUT32_PS_STRINGS \
+    (AOUT32_USRSTACK - sizeof(struct freebsd32_ps_strings))
+
+extern const char *freebsd32_syscallnames[];
+extern u_long ia32_maxssiz;
+
+struct sysentvec aout_sysvec = {
+	.sv_size	= FREEBSD32_SYS_MAXSYSCALL,
+	.sv_table	= freebsd32_sysent,
+	.sv_mask	= 0,
+	.sv_sigsize	= 0,
+	.sv_sigtbl	= NULL,
+	.sv_errsize	= 0,
+	.sv_errtbl	= NULL,
+	.sv_transtrap	= NULL,
+	.sv_fixup	= aout_fixup,
+	.sv_sendsig	= ia32_sendsig,
+	.sv_sigcode	= ia32_sigcode,
+	.sv_szsigcode	= &sz_ia32_sigcode,
+	.sv_prepsyscall	= NULL,
+	.sv_name	= "FreeBSD a.out",
+	.sv_coredump	= NULL,
+	.sv_imgact_try	= NULL,
+	.sv_minsigstksz	= MINSIGSTKSZ,
+	.sv_pagesize	= IA32_PAGE_SIZE,
+	.sv_minuser	= 0,
+	.sv_maxuser	= AOUT32_USRSTACK,
+	.sv_usrstack	= AOUT32_USRSTACK,
+	.sv_psstrings	= AOUT32_PS_STRINGS,
+	.sv_stackprot	= VM_PROT_ALL,
+	.sv_copyout_strings	= freebsd32_copyout_strings,
+	.sv_setregs	= ia32_setregs,
+	.sv_fixlimit	= ia32_fixlimit,
+	.sv_maxssiz	= &ia32_maxssiz,
+	.sv_flags	= SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
+	.sv_set_syscall_retval = ia32_set_syscall_retval,
+	.sv_fetch_syscall_args = ia32_fetch_syscall_args,
+	.sv_syscallnames = freebsd32_syscallnames,
+};
+#else
+#error "Port me"
+#endif
+
 static int
-aout_fixup(stack_base, imgp)
-	register_t **stack_base;
-	struct image_params *imgp;
+aout_fixup(register_t **stack_base, struct image_params *imgp)
 {
 
-	return (suword(--(*stack_base), imgp->args->argc));
+	*(char **)stack_base -= sizeof(uint32_t);
+	return (suword(*stack_base, imgp->args->argc));
 }
 
 static int
-exec_aout_imgact(imgp)
-	struct image_params *imgp;
+exec_aout_imgact(struct image_params *imgp)
 {
 	const struct exec *a_out = (const struct exec *) imgp->image_header;
 	struct vmspace *vmspace;
@@ -175,7 +223,14 @@ exec_aout_imgact(imgp)
 	    a_out->a_entry >= virtual_offset + a_out->a_text ||
 
 	    /* text and data size must each be page rounded */
-	    a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK)
+	    a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK
+
+#ifdef __amd64__
+	    ||
+	    /* overflows */
+	    virtual_offset + a_out->a_text + a_out->a_data + bss_size > UINT_MAX
+#endif
+	    )
 		return (-1);
 
 	/* text + data can't exceed file size */