aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT

Suppress A.OUT library support if CONFIG_ARCH_SUPPORTS_AOUT is not set.

Not all architectures support the A.OUT binfmt, so the ELF binfmt should not
be permitted to go looking for A.OUT libraries to load in such a case.  Not
only that, but under such conditions A.OUT core dumps are not produced either.

To make this work, this patch also does the following:

 (1) Makes the existence of the contents of linux/a.out.h contingent on
     CONFIG_ARCH_SUPPORTS_AOUT.

 (2) Renames dump_thread() to aout_dump_thread() as it's only called by A.OUT
     core dumping code.

 (3) Moves aout_dump_thread() into asm/a.out-core.h and makes it inline.  This
     is then included only where needed.  This means that this bit of arch
     code will be stored in the appropriate A.OUT binfmt module rather than
     the core kernel.

 (4) Drops A.OUT support for Blackfin (according to Mike Frysinger it's not
     needed) and FRV.

This patch depends on the previous patch to move STACK_TOP[_MAX] out of
asm/a.out.h and into asm/processor.h as they're required whether or not A.OUT
format is available.

[jdike@addtoit.com: uml: re-remove accidentally restored code]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 8 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 111771d..a93b117 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -513,6 +513,7 @@ out:
 	return error;
 }
 
+#ifdef CONFIG_ARCH_SUPPORTS_AOUT
 static unsigned long load_aout_interp(struct exec *interp_ex,
 		struct file *interpreter)
 {
@@ -558,6 +559,14 @@ static unsigned long load_aout_interp(struct exec *interp_ex,
 out:
 	return elf_entry;
 }
+#else
+/* dummy extern - the function should never be called if !CONFIG_AOUT_BINFMT */
+static inline unsigned long load_aout_interp(struct exec *interp_ex,
+					     struct file *interpreter)
+{
+	return -ELIBACC;
+}
+#endif
 
 /*
  * These are the functions used to load ELF style executables and shared
@@ -565,9 +574,15 @@ out:
  */
 
 #define INTERPRETER_NONE 0
-#define INTERPRETER_AOUT 1
 #define INTERPRETER_ELF 2
 
+#ifdef CONFIG_ARCH_SUPPORTS_AOUT
+#define INTERPRETER_AOUT 1
+#define IS_AOUT_INTERP(x) ((x) == INTERPRETER_AOUT)
+#else
+#define IS_AOUT_INTERP(x) (0)
+#endif
+
 #ifndef STACK_RND_MASK
 #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))	/* 8MB of VA */
 #endif
@@ -775,6 +790,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 	/* Some simple consistency checks for the interpreter */
 	if (elf_interpreter) {
 		static int warn;
+#ifdef CONFIG_ARCH_SUPPORTS_AOUT
 		interpreter_type = INTERPRETER_ELF | INTERPRETER_AOUT;
 
 		/* Now figure out which format our binary is */
@@ -782,11 +798,13 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 		    (N_MAGIC(loc->interp_ex) != ZMAGIC) &&
 		    (N_MAGIC(loc->interp_ex) != QMAGIC))
 			interpreter_type = INTERPRETER_ELF;
-
+#else
+		interpreter_type = INTERPRETER_ELF;
+#endif
 		if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
 			interpreter_type &= ~INTERPRETER_ELF;
 
-		if (interpreter_type == INTERPRETER_AOUT && warn < 10) {
+		if (IS_AOUT_INTERP(interpreter_type) && warn < 10) {
 			printk(KERN_WARNING "a.out ELF interpreter %s is "
 				"deprecated and will not be supported "
 				"after Linux 2.6.25\n", elf_interpreter);
@@ -815,7 +833,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 
 	/* OK, we are done with that, now set up the arg stuff,
 	   and then start this sucker up */
-	if ((!bprm->sh_bang) && (interpreter_type == INTERPRETER_AOUT)) {
+	if (IS_AOUT_INTERP(interpreter_type) && !bprm->sh_bang) {
 		char *passed_p = passed_fileno;
 		sprintf(passed_fileno, "%d", elf_exec_fileno);
 
@@ -1004,7 +1022,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 	}
 
 	if (elf_interpreter) {
-		if (interpreter_type == INTERPRETER_AOUT) {
+		if (IS_AOUT_INTERP(interpreter_type)) {
 			elf_entry = load_aout_interp(&loc->interp_ex,
 						     interpreter);
 		} else {
@@ -1045,7 +1063,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 
 	kfree(elf_phdata);
 
-	if (interpreter_type != INTERPRETER_AOUT)
+	if (!IS_AOUT_INTERP(interpreter_type))
 		sys_close(elf_exec_fileno);
 
 	set_binfmt(&elf_format);
@@ -1061,14 +1079,14 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 	compute_creds(bprm);
 	current->flags &= ~PF_FORKNOEXEC;
 	retval = create_elf_tables(bprm, &loc->elf_ex,
-			  (interpreter_type == INTERPRETER_AOUT),
+			  IS_AOUT_INTERP(interpreter_type),
 			  load_addr, interp_load_addr);
 	if (retval < 0) {
 		send_sig(SIGKILL, current, 0);
 		goto out;
 	}
 	/* N.B. passed_fileno might not be initialized? */
-	if (interpreter_type == INTERPRETER_AOUT)
+	if (IS_AOUT_INTERP(interpreter_type))
 		current->mm->arg_start += strlen(passed_fileno) + 1;
 	current->mm->end_code = end_code;
 	current->mm->start_code = start_code;