Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1447413 > unrolled thread

[PATCH v4 00/12] allow BFLT executables on systems with a MMU

Back to article view | Back to linux.kernel

Contents

  [PATCH v4 00/12] allow BFLT executables on systems with a MMU Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 10/12] binfmt_flat: update libraries' data segment pointer with userspace accessors Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 06/12] binfmt_flat: clean up create_flat_tables() and stack accesses Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 02/12] binfmt_flat: convert printk invocations to their modern form Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 09/12] binfmt_flat: use clear_user() rather than memset() to clear .bss Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 07/12] binfmt_flat: use proper user space accessors with relocs processing code Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    [PATCH v4 05/12] binfmt_flat: use generic transfer_args_to_stack() Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-20 21:30 +0200
    Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU Greg Ungerer <gerg@linux-m68k.org> - 2016-07-21 09:00 +0200
      Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-21 16:50 +0200
        Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU Greg Ungerer <gerg@linux-m68k.org> - 2016-07-22 09:30 +0200
          Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-07-22 17:10 +0200
          Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU Russell King - ARM Linux <linux@armlinux.org.uk> - 2016-07-22 21:30 +0200
            Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-22 21:50 +0200

#1447413 — [PATCH v4 00/12] allow BFLT executables on systems with a MMU

This series provides the necessary changes to allow "flat" executable
binaries meant for no-MMU systems to actually run on systems with a MMU.
Also thrown in are various cleanups to binfmt_flat.c.

This can also be found in the following git repo:

	git://git.linaro.org/people/nicolas.pitre/linux binfmt_flat_with_mmu

*Why?*

Because developing and testing natively on a large system with lots of
RAM makes it so much more convenient to use all the existing profiling
tools and debugging facilities that a kernel with lots of RAM can give.
And incidentally, those systems with lots of RAM all have a MMU.

*Why not use elf_fdpic?*

The flat executable format is simple with very small footprint
overhead, either in the executables themselves or kernel support.
This makes the flat format more suitable than elf_fdpic for very small
single-user-app embedded systems.

And while elf_fdpic binaries can run on MMU systems, flat binaries still
couldn't, which just felt wrong.

So here it is. The no-MMU support should remain unaffected, confirmed by
Greg Ungerer. Tested on ARM with MMU only with a busybox build.

Please consider for merging.

Changes since v3:

- Small cosmetic changes to pr_*().

- Addressed most important checkpatch complaints on the whole source file
  and patches in this seris.

Changes since  v2:

- Added protection against a corrupted header that could have caused nasty
  overflows etc. Suggested by Alan Cox.

- printk() modernization. Suggested by Greg Ungerer / Geert Uytterhoeven.

- Added Greg Ungerer's reviewed-by tag.

Changes since v1:

- Removed SuperH and Xtensa from the Kconfig rule as they fail to build
  due to lack of get/put_unaligned_user().

- Clarified some commit logs a bit.

diffstat:
 arch/arm/include/asm/flat.h  |   5 +-
 arch/m68k/include/asm/flat.h |   5 +-
 fs/Kconfig.binfmt            |   3 +-
 fs/binfmt_elf_fdpic.c        |  38 +--
 fs/binfmt_flat.c             | 525 +++++++++++++++++++++----------------
 fs/exec.c                    |  33 +++
 include/linux/binfmts.h      |   2 +
 7 files changed, 339 insertions(+), 272 deletions(-)

[toc] | [next] | [standalone]

#1447414 — [PATCH v4 10/12] binfmt_flat: update libraries' data segment pointer with userspace accessors

This is needed on systems with a MMU.  This also gets rid of the
strangest C code I've seen lateli i.e. an integer indexed with a
pointer value within square brackets. That really looked backwards.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 92c1530a2c..aa7971ce6a 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -894,12 +894,19 @@ static int load_flat_binary(struct linux_binprm *bprm)
 		return res;
 
 	/* Update data segment pointers for all libraries */
-	for (i = 0; i < MAX_SHARED_LIBS; i++)
-		if (libinfo.lib_list[i].loaded)
-			for (j = 0; j < MAX_SHARED_LIBS; j++)
-				(-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
-					(libinfo.lib_list[j].loaded) ?
-						libinfo.lib_list[j].start_data : UNLOADED_LIB;
+	for (i = 0; i < MAX_SHARED_LIBS; i++) {
+		if (!libinfo.lib_list[i].loaded)
+			continue;
+		for (j = 0; j < MAX_SHARED_LIBS; j++) {
+			unsigned long val = libinfo.lib_list[j].loaded ?
+				libinfo.lib_list[j].start_data : UNLOADED_LIB;
+			unsigned long __user *p = (unsigned long __user *)
+				libinfo.lib_list[i].start_data;
+			p -= j + 1;
+			if (put_user(val, p))
+				return -EFAULT;
+		}
+	}
 
 	install_exec_creds(bprm);
 
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447415 — [PATCH v4 06/12] binfmt_flat: clean up create_flat_tables() and stack accesses

In addition to better code clarity, this brings proper usage of
user memory accessors everywhere the stack is touched. This is essential
for making this work on MMU systems.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 117 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 63 insertions(+), 54 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index a002e1a3b9..5dc7968a42 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -103,50 +103,58 @@ static int flat_core_dump(struct coredump_params *cprm)
 /*
  * create_flat_tables() parses the env- and arg-strings in new user
  * memory and creates the pointer tables from them, and puts their
- * addresses on the "stack", returning the new stack pointer value.
+ * addresses on the "stack", recording the new stack pointer value.
  */
 
-static unsigned long create_flat_tables(
-	unsigned long pp,
-	struct linux_binprm *bprm)
+static int create_flat_tables(struct linux_binprm *bprm, unsigned long arg_start)
 {
-	unsigned long *argv, *envp;
-	unsigned long *sp;
-	char *p = (char *)pp;
-	int argc = bprm->argc;
-	int envc = bprm->envc;
-	char uninitialized_var(dummy);
-
-	sp = (unsigned long *)p;
-	sp -= (envc + argc + 2) + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
-	sp = (unsigned long *) ((unsigned long)sp & -FLAT_STACK_ALIGN);
-	argv = sp + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
-	envp = argv + (argc + 1);
+	char __user *p;
+	unsigned long __user *sp;
+	long i, len;
 
+	p = (char __user *)arg_start;
+	sp = (unsigned long __user *)current->mm->start_stack;
+
+	sp -= bprm->envc + 1;
+	sp -= bprm->argc + 1;
+	sp -= flat_argvp_envp_on_stack() ? 2 : 0;
+	sp -= 1;  /* &argc */
+
+	current->mm->start_stack = (unsigned long)sp & -FLAT_STACK_ALIGN;
+	sp = (unsigned long __user *)current->mm->start_stack;
+
+	__put_user(bprm->argc, sp++);
 	if (flat_argvp_envp_on_stack()) {
-		put_user((unsigned long) envp, sp + 2);
-		put_user((unsigned long) argv, sp + 1);
-	}
-
-	put_user(argc, sp);
-	current->mm->arg_start = (unsigned long) p;
-	while (argc-- > 0) {
-		put_user((unsigned long) p, argv++);
-		do {
-			get_user(dummy, p); p++;
-		} while (dummy);
-	}
-	put_user((unsigned long) NULL, argv);
-	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
-	while (envc-- > 0) {
-		put_user((unsigned long)p, envp); envp++;
-		do {
-			get_user(dummy, p); p++;
-		} while (dummy);
-	}
-	put_user((unsigned long) NULL, envp);
-	current->mm->env_end = (unsigned long) p;
-	return (unsigned long)sp;
+		unsigned long argv, envp;
+		argv = (unsigned long)(sp + 2);
+		envp = (unsigned long)(sp + 2 + bprm->argc + 1);
+		__put_user(argv, sp++);
+		__put_user(envp, sp++);
+	}
+
+	current->mm->arg_start = (unsigned long)p;
+	for (i = bprm->argc; i > 0; i--) {
+		__put_user((unsigned long)p, sp++);
+		len = strnlen_user(p, MAX_ARG_STRLEN);
+		if (!len || len > MAX_ARG_STRLEN)
+			return -EINVAL;
+		p += len;
+	}
+	__put_user(0, sp++);
+	current->mm->arg_end = (unsigned long)p;
+
+	current->mm->env_start = (unsigned long) p;
+	for (i = bprm->envc; i > 0; i--) {
+		__put_user((unsigned long)p, sp++);
+		len = strnlen_user(p, MAX_ARG_STRLEN);
+		if (!len || len > MAX_ARG_STRLEN)
+			return -EINVAL;
+		p += len;
+	}
+	__put_user(0, sp++);
+	current->mm->env_end = (unsigned long)p;
+
+	return 0;
 }
 
 /****************************************************************************/
@@ -846,7 +854,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
-	unsigned long sp, stack_len;
+	unsigned long stack_len;
 	unsigned long start_addr;
 	int res;
 	int i, j;
@@ -860,11 +868,10 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	 * pedantic and include space for the argv/envp array as it may have
 	 * a lot of entries.
 	 */
-#define TOP_OF_ARGS (PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *))
-	stack_len = TOP_OF_ARGS - bprm->p;             /* the strings */
-	stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
-	stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
-	stack_len += FLAT_STACK_ALIGN - 1;  /* reserve for upcoming alignment */
+	stack_len = PAGE_SIZE * MAX_ARG_PAGES - bprm->p;  /* the strings */
+	stack_len += (bprm->argc + 1) * sizeof(char *);   /* the argv array */
+	stack_len += (bprm->envc + 1) * sizeof(char *);   /* the envp array */
+	stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
 
 	res = load_flat_file(bprm, &libinfo, 0, &stack_len);
 	if (res < 0)
@@ -882,16 +889,18 @@ static int load_flat_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&flat_format);
 
-	sp = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	pr_debug("sp=%lx\n", sp);
+	/* Stash our initial stack pointer into the mm structure */
+	current->mm->start_stack =
+		((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
+	pr_debug("sp=%lx\n", current->mm->start_stack);
 
 	/* copy the arg pages onto the stack */
-	res = transfer_args_to_stack(bprm, &sp);
+	res = transfer_args_to_stack(bprm, &current->mm->start_stack);
+	if (!res)
+		res = create_flat_tables(bprm, current->mm->start_stack);
 	if (res)
 		return res;
 
-	sp = create_flat_tables(sp, bprm);
-
 	/* Fake some return addresses to ensure the call chain will
 	 * initialise library in order for us.  We are required to call
 	 * lib 1 first, then 2, ... and finally the main program (id 0).
@@ -902,15 +911,15 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
 		if (libinfo.lib_list[i].loaded) {
 			/* Push previos first to call address */
-			--sp;	put_user(start_addr, (unsigned long *)sp);
+			unsigned long __user *sp;
+			current->mm->start_stack -= sizeof(unsigned long);
+			sp = (unsigned long __user *)current->mm->start_stack;
+			__put_user(start_addr, sp);
 			start_addr = libinfo.lib_list[i].entry;
 		}
 	}
 #endif
 
-	/* Stash our initial stack pointer into the mm structure */
-	current->mm->start_stack = sp;
-
 #ifdef FLAT_PLAT_INIT
 	FLAT_PLAT_INIT(regs);
 #endif
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447416 — [PATCH v4 02/12] binfmt_flat: convert printk invocations to their modern form

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 fs/binfmt_flat.c | 118 ++++++++++++++++++++++++-------------------------------
 1 file changed, 51 insertions(+), 67 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 892dba62bf..c3ccdefdea 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -15,6 +15,8 @@
  *	JAN/99 -- coded full program relocation (gerg@snapgear.com)
  */
 
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -40,16 +42,6 @@
 
 /****************************************************************************/
 
-#if 0
-#define DEBUG 1
-#endif
-
-#ifdef DEBUG
-#define	DBG_FLT(a...)	printk(a)
-#else
-#define	DBG_FLT(a...)
-#endif
-
 /*
  * User data (data section and bss) needs to be aligned.
  * We pick 0x20 here because it is the max value elf2flt has always
@@ -102,8 +94,8 @@ static struct linux_binfmt flat_format = {
 
 static int flat_core_dump(struct coredump_params *cprm)
 {
-	printk("Process %s:%d received signr %d and should have core dumped\n",
-			current->comm, current->pid, cprm->siginfo->si_signo);
+	pr_warn("Process %s:%d received signr %d and should have core dumped\n",
+		current->comm, current->pid, cprm->siginfo->si_signo);
 	return 1;
 }
 
@@ -186,17 +178,17 @@ static int decompress_exec(
 	loff_t fpos;
 	int ret, retval;
 
-	DBG_FLT("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);
+	pr_debug("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);
 
 	memset(&strm, 0, sizeof(strm));
 	strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
 	if (strm.workspace == NULL) {
-		DBG_FLT("binfmt_flat: no memory for decompress workspace\n");
+		pr_debug("no memory for decompress workspace\n");
 		return -ENOMEM;
 	}
 	buf = kmalloc(LBUFSIZE, GFP_KERNEL);
 	if (buf == NULL) {
-		DBG_FLT("binfmt_flat: no memory for read buffer\n");
+		pr_debug("no memory for read buffer\n");
 		retval = -ENOMEM;
 		goto out_free;
 	}
@@ -214,25 +206,25 @@ static int decompress_exec(
 
 	/* Check minimum size -- gzip header */
 	if (ret < 10) {
-		DBG_FLT("binfmt_flat: file too small?\n");
+		pr_debug("file too small?\n");
 		goto out_free_buf;
 	}
 
 	/* Check gzip magic number */
 	if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
-		DBG_FLT("binfmt_flat: unknown compression magic?\n");
+		pr_debug("unknown compression magic?\n");
 		goto out_free_buf;
 	}
 
 	/* Check gzip method */
 	if (buf[2] != 8) {
-		DBG_FLT("binfmt_flat: unknown compression method?\n");
+		pr_debug("unknown compression method?\n");
 		goto out_free_buf;
 	}
 	/* Check gzip flags */
 	if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
 	    (buf[3] & RESERVED)) {
-		DBG_FLT("binfmt_flat: unknown flags?\n");
+		pr_debug("unknown flags?\n");
 		goto out_free_buf;
 	}
 
@@ -240,7 +232,7 @@ static int decompress_exec(
 	if (buf[3] & EXTRA_FIELD) {
 		ret += 2 + buf[10] + (buf[11] << 8);
 		if (unlikely(ret >= LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
+			pr_debug("buffer overflow (EXTRA)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -248,7 +240,7 @@ static int decompress_exec(
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
 		if (unlikely(ret == LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
+			pr_debug("buffer overflow (ORIG_NAME)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -256,7 +248,7 @@ static int decompress_exec(
 		while (ret < LBUFSIZE && buf[ret++] != 0)
 			;
 		if (unlikely(ret == LBUFSIZE)) {
-			DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
+			pr_debug("buffer overflow (COMMENT)?\n");
 			goto out_free_buf;
 		}
 	}
@@ -269,7 +261,7 @@ static int decompress_exec(
 	strm.total_out = 0;
 
 	if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
-		DBG_FLT("binfmt_flat: zlib init failed?\n");
+		pr_debug("zlib init failed?\n");
 		goto out_free_buf;
 	}
 
@@ -286,7 +278,7 @@ static int decompress_exec(
 	}
 
 	if (ret < 0) {
-		DBG_FLT("binfmt_flat: decompression failed (%d), %s\n",
+		pr_debug("decompression failed (%d), %s\n",
 			ret, strm.msg);
 		goto out_zlib;
 	}
@@ -323,24 +315,23 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 		r &= 0x00ffffff;	/* Trim ID off here */
 	}
 	if (id >= MAX_SHARED_LIBS) {
-		printk("BINFMT_FLAT: reference 0x%lx to shared library %d",
-				r, id);
+		pr_err("reference 0x%lx to shared library %d", r, id);
 		goto failed;
 	}
 	if (curid != id) {
 		if (internalp) {
-			printk("BINFMT_FLAT: reloc address 0x%lx not in same module "
-					"(%d != %d)", r, curid, id);
+			pr_err("reloc address 0x%lx not in same module "
+			       "(%d != %d)", r, curid, id);
 			goto failed;
 		} else if (!p->lib_list[id].loaded &&
 			   load_flat_shared_library(id, p) < 0) {
-			printk("BINFMT_FLAT: failed to load library %d", id);
+			pr_err("failed to load library %d", id);
 			goto failed;
 		}
 		/* Check versioning information (i.e. time stamps) */
 		if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
 				p->lib_list[curid].build_date < p->lib_list[id].build_date) {
-			printk("BINFMT_FLAT: library %d is younger than %d", id, curid);
+			pr_err("library %d is younger than %d", id, curid);
 			goto failed;
 		}
 	}
@@ -354,7 +345,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 	text_len = p->lib_list[id].text_len;
 
 	if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
-		printk("BINFMT_FLAT: reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
+		pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
 		       r, start_brk-start_data+text_len, text_len);
 		goto failed;
 	}
@@ -368,7 +359,7 @@ calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
 	return addr;
 
 failed:
-	printk(", killing %s!\n", current->comm);
+	pr_cont(", killing %s!\n", current->comm);
 	send_sig(SIGSEGV, current, 0);
 
 	return RELOC_FAILED;
@@ -378,9 +369,7 @@ failed:
 
 static void old_reloc(unsigned long rl)
 {
-#ifdef DEBUG
 	static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
-#endif
 	flat_v2_reloc_t	r;
 	unsigned long *ptr;
 
@@ -391,11 +380,9 @@ static void old_reloc(unsigned long rl)
 	ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
 #endif
 
-#ifdef DEBUG
-	printk("Relocation of variable at DATASEG+%x "
-		"(address %p, currently %lx) into segment %s\n",
-		r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
-#endif
+	pr_debug("Relocation of variable at DATASEG+%x "
+		 "(address %p, currently %lx) into segment %s\n",
+		 r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
 
 	switch (r.reloc.type) {
 	case OLD_FLAT_RELOC_TYPE_TEXT:
@@ -408,13 +395,11 @@ static void old_reloc(unsigned long rl)
 		*ptr += current->mm->end_data;
 		break;
 	default:
-		printk("BINFMT_FLAT: Unknown relocation type=%x\n", r.reloc.type);
+		pr_err("Unknown relocation type=%x\n", r.reloc.type);
 		break;
 	}
 
-#ifdef DEBUG
-	printk("Relocation became %lx\n", *ptr);
-#endif
+	pr_debug("Relocation became %lx\n", *ptr);
 }
 
 /****************************************************************************/
@@ -463,20 +448,19 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	if (flags & FLAT_FLAG_KTRACE)
-		printk("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
+		pr_info("Loading file: %s\n", bprm->filename);
 
 	if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
-		printk("BINFMT_FLAT: bad flat file version 0x%x (supported "
-			"0x%lx and 0x%lx)\n",
-			rev, FLAT_VERSION, OLD_FLAT_VERSION);
+		pr_err("bad flat file version 0x%x (supported 0x%lx and 0x%lx)\n",
+		       rev, FLAT_VERSION, OLD_FLAT_VERSION);
 		ret = -ENOEXEC;
 		goto err;
 	}
 
 	/* Don't allow old format executables to use shared libraries */
 	if (rev == OLD_FLAT_VERSION && id != 0) {
-		printk("BINFMT_FLAT: shared libraries are not available before rev 0x%lx\n",
-				FLAT_VERSION);
+		pr_err("shared libraries are not available before rev 0x%lx\n",
+		       FLAT_VERSION);
 		ret = -ENOEXEC;
 		goto err;
 	}
@@ -490,7 +474,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 
 #ifndef CONFIG_BINFMT_ZFLAT
 	if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
-		printk("Support for ZFLAT executables is not enabled.\n");
+		pr_err("Support for ZFLAT executables is not enabled.\n");
 		ret = -ENOEXEC;
 		goto err;
 	}
@@ -536,7 +520,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		 * this should give us a ROM ptr,  but if it doesn't we don't
 		 * really care
 		 */
-		DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
+		pr_debug("ROM mapping of file (we hope)\n");
 
 		textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
 				  MAP_PRIVATE|MAP_EXECUTABLE, 0);
@@ -544,7 +528,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = textpos;
 			if (!textpos)
 				ret = -ENOMEM;
-			printk("Unable to mmap process text, errno %d\n", ret);
+			pr_err("Unable to mmap process text, errno %d\n", ret);
 			goto err;
 		}
 
@@ -557,7 +541,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = realdatastart;
 			if (!realdatastart)
 				ret = -ENOMEM;
-			printk("Unable to allocate RAM for process data, "
+			pr_err("Unable to allocate RAM for process data, "
 			       "errno %d\n", ret);
 			vm_munmap(textpos, text_len);
 			goto err;
@@ -566,8 +550,8 @@ static int load_flat_file(struct linux_binprm *bprm,
 				MAX_SHARED_LIBS * sizeof(unsigned long),
 				FLAT_DATA_ALIGN);
 
-		DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%ld bytes): %lx\n",
-			data_len + bss_len + stack_len, datapos);
+		pr_debug("Allocated data+bss+stack (%ld bytes): %lx\n",
+			 data_len + bss_len + stack_len, datapos);
 
 		fpos = ntohl(hdr->data_start);
 #ifdef CONFIG_BINFMT_ZFLAT
@@ -582,7 +566,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		}
 		if (IS_ERR_VALUE(result)) {
 			ret = result;
-			printk("Unable to read data+bss, errno %d\n", ret);
+			pr_err("Unable to read data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len);
 			vm_munmap(realdatastart, len);
 			goto err;
@@ -603,7 +587,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			ret = textpos;
 			if (!textpos)
 				ret = -ENOMEM;
-			printk("Unable to allocate RAM for process text/data, "
+			pr_err("Unable to allocate RAM for process text/data, "
 			       "errno %d\n", ret);
 			goto err;
 		}
@@ -645,7 +629,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 		}
 		if (IS_ERR_VALUE(result)) {
 			ret = result;
-			printk("Unable to read code+data+bss, errno %d\n", ret);
+			pr_err("Unable to read code+data+bss, errno %d\n", ret);
 			vm_munmap(textpos, text_len + data_len + extra +
 				MAX_SHARED_LIBS * sizeof(unsigned long));
 			goto err;
@@ -675,12 +659,12 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	if (flags & FLAT_FLAG_KTRACE) {
-		printk("Mapping is %lx, Entry point is %x, data_start is %x\n",
-		       textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
-		printk("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
-		       id ? "Lib" : "Load", bprm->filename,
-		       start_code, end_code, datapos, datapos + data_len,
-		       datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
+		pr_info("Mapping is %lx, Entry point is %x, data_start is %x\n",
+			textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
+		pr_info("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
+			id ? "Lib" : "Load", bprm->filename,
+			start_code, end_code, datapos, datapos + data_len,
+			datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
 	}
 
 	/* Store the current module values into the global library structure */
@@ -890,7 +874,7 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	set_binfmt(&flat_format);
 
 	p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	DBG_FLT("p=%lx\n", p);
+	pr_debug("p=%lx\n", p);
 
 	/* copy the arg pages onto the stack, this could be more efficient :-) */
 	for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
@@ -922,8 +906,8 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	FLAT_PLAT_INIT(regs);
 #endif
 
-	DBG_FLT("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
-		regs, start_addr, current->mm->start_stack);
+	pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
+		 regs, start_addr, current->mm->start_stack);
 	start_thread(regs, start_addr, current->mm->start_stack);
 
 	return 0;
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447417 — [PATCH v4 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 fs/binfmt_flat.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index c3ccdefdea..03301bad1f 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -466,6 +466,17 @@ static int load_flat_file(struct linux_binprm *bprm,
 	}
 
 	/*
+	 * Make sure the header params are sane.
+	 * 28 bits (256 MB) is way more than reasonable in this case.
+	 * If some top bits are set we have probable binary corruption.
+	*/
+	if ((text_len | data_len | bss_len | stack_len | full_data) >> 28) {
+		pr_err("bad header\n");
+		ret = -ENOEXEC;
+		goto err;
+	}
+
+	/*
 	 * fix up the flags for the older format,  there were all kinds
 	 * of endian hacks,  this only works for the simple cases
 	 */
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447418 — [PATCH v4 09/12] binfmt_flat: use clear_user() rather than memset() to clear .bss

This is needed on systems with a MMU.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 63756ca6a7..92c1530a2c 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -795,10 +795,11 @@ static int load_flat_file(struct linux_binprm *bprm,
 	flush_icache_range(start_code, end_code);
 
 	/* zero the BSS,  BRK and stack areas */
-	memset((void *)(datapos + data_len), 0, bss_len +
-			(memp + memp_size - stack_len -		/* end brk */
-			libinfo->lib_list[id].start_brk) +	/* start brk */
-			stack_len);
+	if (clear_user((void __user *)(datapos + data_len), bss_len +
+		       (memp + memp_size - stack_len -		/* end brk */
+		       libinfo->lib_list[id].start_brk) +	/* start brk */
+		       stack_len))
+		return -EFAULT;
 
 	return 0;
 err:
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447419 — [PATCH v4 07/12] binfmt_flat: use proper user space accessors with relocs processing code

Relocs are fixed up in place in user space memory.  The appropriate
accessors are required for this code to work with an active MMU.

The architecture specific handlers for ARM and M68K are also
covered. SuperH and Xtensa are left out as they doesn't implement
__get_user_unaligned() and __put_user_unaligned() yet. The other
architectures that use BFLT don't have any MMU.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 arch/arm/include/asm/flat.h  |  5 +++--
 arch/m68k/include/asm/flat.h |  5 +++--
 fs/binfmt_flat.c             | 31 +++++++++++++++++++------------
 3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/arch/arm/include/asm/flat.h b/arch/arm/include/asm/flat.h
index e847d23351..acf1d14b89 100644
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -8,8 +8,9 @@
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
-#define	flat_get_addr_from_rp(rp, relval, flags, persistent) ((void)persistent,get_unaligned(rp))
-#define	flat_put_addr_at_rp(rp, val, relval)	put_unaligned(val,rp)
+#define	flat_get_addr_from_rp(rp, relval, flags, persistent) \
+	({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define	flat_put_addr_at_rp(rp, val, relval)	__put_user_unaligned(val, rp)
 #define	flat_get_relocate_addr(rel)		(rel)
 #define	flat_set_persistent(relval, p)		0
 
diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f9454b89a5..f3f592d03e 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -8,8 +8,9 @@
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
-#define	flat_get_addr_from_rp(rp, relval, flags, p)	get_unaligned(rp)
-#define	flat_put_addr_at_rp(rp, val, relval)	put_unaligned(val,rp)
+#define	flat_get_addr_from_rp(rp, relval, flags, p) \
+	({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define	flat_put_addr_at_rp(rp, val, relval)	__put_user_unaligned(val, rp)
 #define	flat_get_relocate_addr(rel)		(rel)
 
 static inline int flat_set_persistent(unsigned long relval,
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 5dc7968a42..9deafb282d 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -419,7 +419,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 	unsigned long textpos, datapos, realdatastart;
 	unsigned long text_len, data_len, bss_len, stack_len, full_data, flags;
 	unsigned long len, memp, memp_size, extra, rlim;
-	unsigned long *reloc, *rp;
+	unsigned long __user *reloc, *rp;
 	struct inode *inode;
 	int i, rev, relocs;
 	loff_t fpos;
@@ -591,7 +591,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 			goto err;
 		}
 
-		reloc = (unsigned long *)
+		reloc = (unsigned long __user *)
 			(datapos + (ntohl(hdr->reloc_start) - text_len));
 		memp = realdatastart;
 		memp_size = len;
@@ -616,7 +616,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 				MAX_SHARED_LIBS * sizeof(unsigned long),
 				FLAT_DATA_ALIGN);
 
-		reloc = (unsigned long *)
+		reloc = (unsigned long __user *)
 			(datapos + (ntohl(hdr->reloc_start) - text_len));
 		memp = textpos;
 		memp_size = len;
@@ -708,15 +708,20 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * image.
 	 */
 	if (flags & FLAT_FLAG_GOTPIC) {
-		for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) {
-			unsigned long addr;
-			if (*rp) {
-				addr = calc_reloc(*rp, libinfo, id, 0);
+		for (rp = (unsigned long __user *)datapos; ; rp++) {
+			unsigned long addr, rp_val;
+			if (get_user(rp_val, rp))
+				return -EFAULT;
+			if (rp_val == 0xffffffff)
+				break;
+			if (rp_val) {
+				addr = calc_reloc(rp_val, libinfo, id, 0);
 				if (addr == RELOC_FAILED) {
 					ret = -ENOEXEC;
 					goto err;
 				}
-				*rp = addr;
+				if (put_user(addr, rp))
+					return -EFAULT;
 			}
 		}
 	}
@@ -733,7 +738,7 @@ static int load_flat_file(struct linux_binprm *bprm,
 	 * __start to address 4 so that is okay).
 	 */
 	if (rev > OLD_FLAT_VERSION) {
-		unsigned long persistent = 0;
+		unsigned long __maybe_unused persistent = 0;
 		for (i = 0; i < relocs; i++) {
 			unsigned long addr, relval;
 
@@ -742,12 +747,14 @@ static int load_flat_file(struct linux_binprm *bprm,
 			 * relocated (of course, the address has to be
 			 * relocated first).
 			 */
-			relval = ntohl(reloc[i]);
+			if (get_user(relval, reloc + i))
+				return -EFAULT;
+			relval = ntohl(relval);
 			if (flat_set_persistent(relval, &persistent))
 				continue;
 			addr = flat_get_relocate_addr(relval);
-			rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
-			if (rp == (unsigned long *)RELOC_FAILED) {
+			rp = (unsigned long __user *)calc_reloc(addr, libinfo, id, 1);
+			if (rp == (unsigned long __user *)RELOC_FAILED) {
 				ret = -ENOEXEC;
 				goto err;
 			}
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447420 — [PATCH v4 05/12] binfmt_flat: use generic transfer_args_to_stack()

This gets rid of the rather ugly, open coded and suboptimal copy code.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
---
 fs/binfmt_flat.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 03301bad1f..a002e1a3b9 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -846,10 +846,8 @@ static int load_flat_binary(struct linux_binprm *bprm)
 {
 	struct lib_info libinfo;
 	struct pt_regs *regs = current_pt_regs();
-	unsigned long p = bprm->p;
-	unsigned long stack_len;
+	unsigned long sp, stack_len;
 	unsigned long start_addr;
-	unsigned long *sp;
 	int res;
 	int i, j;
 
@@ -884,15 +882,15 @@ static int load_flat_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&flat_format);
 
-	p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
-	pr_debug("p=%lx\n", p);
+	sp = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
+	pr_debug("sp=%lx\n", sp);
 
-	/* copy the arg pages onto the stack, this could be more efficient :-) */
-	for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
-		*(char *) --p =
-			((char *) page_address(bprm->page[i/PAGE_SIZE]))[i % PAGE_SIZE];
+	/* copy the arg pages onto the stack */
+	res = transfer_args_to_stack(bprm, &sp);
+	if (res)
+		return res;
 
-	sp = (unsigned long *) create_flat_tables(p, bprm);
+	sp = create_flat_tables(sp, bprm);
 
 	/* Fake some return addresses to ensure the call chain will
 	 * initialise library in order for us.  We are required to call
@@ -904,14 +902,14 @@ static int load_flat_binary(struct linux_binprm *bprm)
 	for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
 		if (libinfo.lib_list[i].loaded) {
 			/* Push previos first to call address */
-			--sp;	put_user(start_addr, sp);
+			--sp;	put_user(start_addr, (unsigned long *)sp);
 			start_addr = libinfo.lib_list[i].entry;
 		}
 	}
 #endif
 
 	/* Stash our initial stack pointer into the mm structure */
-	current->mm->start_stack = (unsigned long)sp;
+	current->mm->start_stack = sp;
 
 #ifdef FLAT_PLAT_INIT
 	FLAT_PLAT_INIT(regs);
-- 
2.7.4

[toc] | [prev] | [next] | [standalone]

#1447649

Hi Nicolas,

On 21/07/16 05:22, Nicolas Pitre wrote:
> This series provides the necessary changes to allow "flat" executable
> binaries meant for no-MMU systems to actually run on systems with a MMU.
> Also thrown in are various cleanups to binfmt_flat.c.

I got to the bottom of why I couldn't run m68k flat binaries on
an MMU enabled m68k system. I had to fix the regs setup, with the
patch below. With this I can now run flat binaries on my ColdFire
MMU enabled system.

This change is completely independent of your patch series so I'll
push this separately via the linux-m68k list and my m68knommu git
tree.

Regards
Greg



Subject: [PATCH] m68k: fix bFLT executable running on MMU enabled systems

Even after recent changes to support running flat format executables on
MMU enabled systems (by nicolas.pitre@linaro.org) they still failed to
run on m68k/ColdFire MMU enabled systems. On trying to run a flat format
binary the application would immediately crash with a SIGSEGV.

Code to setup the D5 register with the base of the application data
region was only in the non-MMU code path, so it was not being set for
the MMU enabled case. Flat binaries on m68k/ColdFire use this to support
GOT/PIC flat built application code.

Fix this so that D5 is always setup when loading/running a bFLT executable
on m68k systems.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
---
 arch/m68k/include/asm/flat.h      | 6 ++++++
 arch/m68k/include/asm/processor.h | 2 --
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f3f592d..a97c479 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -19,4 +19,10 @@ static inline int flat_set_persistent(unsigned long relval,
 	return 0;
 }
 
+#define FLAT_PLAT_INIT(regs) \
+	do { \
+		if (current->mm) \
+			(regs)->d5 = current->mm->start_data; \
+	} while (0)
+
 #endif /* __M68KNOMMU_FLAT_H__ */
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index a6ce2ec..46672d1 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -131,8 +131,6 @@ extern int handle_kernel_fault(struct pt_regs *regs);
 do {                                                    \
 	(_regs)->pc = (_pc);                            \
 	setframeformat(_regs);                          \
-	if (current->mm)                                \
-		(_regs)->d5 = current->mm->start_data;  \
 	(_regs)->sr &= ~0x2000;                         \
 	wrusp(_usp);                                    \
 } while(0)
-- 
1.9.1

[toc] | [prev] | [next] | [standalone]

#1447935

On Thu, 21 Jul 2016, Greg Ungerer wrote:

> Hi Nicolas,
> 
> On 21/07/16 05:22, Nicolas Pitre wrote:
> > This series provides the necessary changes to allow "flat" executable
> > binaries meant for no-MMU systems to actually run on systems with a MMU.
> > Also thrown in are various cleanups to binfmt_flat.c.
> 
> I got to the bottom of why I couldn't run m68k flat binaries on
> an MMU enabled m68k system. I had to fix the regs setup, with the
> patch below. With this I can now run flat binaries on my ColdFire
> MMU enabled system.

Excellent!

> This change is completely independent of your patch series so I'll
> push this separately via the linux-m68k list and my m68knommu git
> tree.

OK.

Who should merge my patch series at this point?


Nicolas

[toc] | [prev] | [next] | [standalone]

#1448443

On 22/07/16 00:48, Nicolas Pitre wrote:
> On Thu, 21 Jul 2016, Greg Ungerer wrote:
>> Hi Nicolas,
>>
>> On 21/07/16 05:22, Nicolas Pitre wrote:
>>> This series provides the necessary changes to allow "flat" executable
>>> binaries meant for no-MMU systems to actually run on systems with a MMU.
>>> Also thrown in are various cleanups to binfmt_flat.c.
>>
>> I got to the bottom of why I couldn't run m68k flat binaries on
>> an MMU enabled m68k system. I had to fix the regs setup, with the
>> patch below. With this I can now run flat binaries on my ColdFire
>> MMU enabled system.
> 
> Excellent!
> 
>> This change is completely independent of your patch series so I'll
>> push this separately via the linux-m68k list and my m68knommu git
>> tree.
> 
> OK.
> 
> Who should merge my patch series at this point?

If no-one else wants to carry it I can take it in the m68knommu
git tree. But I would want to be sure everyone is good with it
first.

Alan: are you happy with where this is at?
rmk: ok with the arm flat.h change going via another tree?
Al/David: any comments on this?

(Link to v4 patches here https://lkml.org/lkml/2016/7/20/508 )

Regards
Greg

[toc] | [prev] | [next] | [standalone]

#1448623

On Fri, 22 Jul 2016 17:28:13 +1000
Greg Ungerer <gerg@linux-m68k.org> wrote:

> On 22/07/16 00:48, Nicolas Pitre wrote:
> > On Thu, 21 Jul 2016, Greg Ungerer wrote:  
> >> Hi Nicolas,
> >>
> >> On 21/07/16 05:22, Nicolas Pitre wrote:  
> >>> This series provides the necessary changes to allow "flat" executable
> >>> binaries meant for no-MMU systems to actually run on systems with a MMU.
> >>> Also thrown in are various cleanups to binfmt_flat.c.  
> >>
> >> I got to the bottom of why I couldn't run m68k flat binaries on
> >> an MMU enabled m68k system. I had to fix the regs setup, with the
> >> patch below. With this I can now run flat binaries on my ColdFire
> >> MMU enabled system.  
> > 
> > Excellent!
> >   
> >> This change is completely independent of your patch series so I'll
> >> push this separately via the linux-m68k list and my m68knommu git
> >> tree.  
> > 
> > OK.
> > 
> > Who should merge my patch series at this point?  
> 
> If no-one else wants to carry it I can take it in the m68knommu
> git tree. But I would want to be sure everyone is good with it
> first.
> 
> Alan: are you happy with where this is at?

From a first glance yes. I don't have time right now to give it a more
detailed audit, but with the correct user accessors it looks as if all
the ways you can mess up relocations simply result in faults or running a
nonsense binary and the userspace failing.

Alan

[toc] | [prev] | [next] | [standalone]

#1448733

On Fri, Jul 22, 2016 at 05:28:13PM +1000, Greg Ungerer wrote:
> On 22/07/16 00:48, Nicolas Pitre wrote:
> > On Thu, 21 Jul 2016, Greg Ungerer wrote:
> >> Hi Nicolas,
> >>
> >> On 21/07/16 05:22, Nicolas Pitre wrote:
> >>> This series provides the necessary changes to allow "flat" executable
> >>> binaries meant for no-MMU systems to actually run on systems with a MMU.
> >>> Also thrown in are various cleanups to binfmt_flat.c.
> >>
> >> I got to the bottom of why I couldn't run m68k flat binaries on
> >> an MMU enabled m68k system. I had to fix the regs setup, with the
> >> patch below. With this I can now run flat binaries on my ColdFire
> >> MMU enabled system.
> > 
> > Excellent!
> > 
> >> This change is completely independent of your patch series so I'll
> >> push this separately via the linux-m68k list and my m68knommu git
> >> tree.
> > 
> > OK.
> > 
> > Who should merge my patch series at this point?
> 
> If no-one else wants to carry it I can take it in the m68knommu
> git tree. But I would want to be sure everyone is good with it
> first.
> 
> Alan: are you happy with where this is at?
> rmk: ok with the arm flat.h change going via another tree?

I've no idea, sorry.  This is the first I've heard about this as I
haven't been copied with any of the patches, neither has the
linux-arm-kernel mailing list.

> (Link to v4 patches here https://lkml.org/lkml/2016/7/20/508 )

elinks tells me "Unable to retrieve https://lkml.org/lkml/2016/7/20/508:
SSL error" which is a common lkml.org error with elinks.  Also lkml.org
doesn't always work with firefox, especially if you try to follow threads
- I often end up with messages that are missing all content.  Even
openssl s_client gets refused by lkml.org:443 with a fatal SSL error.
(elinks gets "Handshake Failure", openssl gets "Internal Error".)

So, given that no one has seen this on the ARM side, I think there's
a need to post the patches so that it can be reviewed there, especially
so that the wider ARM audience can see what's going on, and ARM64 folk
can see as well.

In any case, I certainly won't be able to review it over this weekend.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

[toc] | [prev] | [next] | [standalone]

#1448738

On Fri, 22 Jul 2016, Russell King - ARM Linux wrote:

> On Fri, Jul 22, 2016 at 05:28:13PM +1000, Greg Ungerer wrote:
> > On 22/07/16 00:48, Nicolas Pitre wrote:
> > > On Thu, 21 Jul 2016, Greg Ungerer wrote:
> > >> Hi Nicolas,
> > >>
> > >> On 21/07/16 05:22, Nicolas Pitre wrote:
> > >>> This series provides the necessary changes to allow "flat" executable
> > >>> binaries meant for no-MMU systems to actually run on systems with a MMU.
> > >>> Also thrown in are various cleanups to binfmt_flat.c.
> > >>
> > >> I got to the bottom of why I couldn't run m68k flat binaries on
> > >> an MMU enabled m68k system. I had to fix the regs setup, with the
> > >> patch below. With this I can now run flat binaries on my ColdFire
> > >> MMU enabled system.
> > > 
> > > Excellent!
> > > 
> > >> This change is completely independent of your patch series so I'll
> > >> push this separately via the linux-m68k list and my m68knommu git
> > >> tree.
> > > 
> > > OK.
> > > 
> > > Who should merge my patch series at this point?
> > 
> > If no-one else wants to carry it I can take it in the m68knommu
> > git tree. But I would want to be sure everyone is good with it
> > first.
> > 
> > Alan: are you happy with where this is at?
> > rmk: ok with the arm flat.h change going via another tree?
> 
> I've no idea, sorry.  This is the first I've heard about this as I
> haven't been copied with any of the patches, neither has the
> linux-arm-kernel mailing list.

This is almost all generic code changes, hence I didn't want to spam too 
many lists with those patches.

> So, given that no one has seen this on the ARM side, I think there's
> a need to post the patches so that it can be reviewed there, especially
> so that the wider ARM audience can see what's going on, and ARM64 folk
> can see as well.

Here's the ARM specific part:

diff --git a/arch/arm/include/asm/flat.h b/arch/arm/include/asm/flat.h
index e847d23351..acf1d14b89 100644
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -8,8 +8,9 @@
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
-#define	flat_get_addr_from_rp(rp, relval, flags, persistent) ((void)persistent,get_unaligned(rp))
-#define	flat_put_addr_at_rp(rp, val, relval)	put_unaligned(val,rp)
+#define	flat_get_addr_from_rp(rp, relval, flags, persistent) \
+	({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define	flat_put_addr_at_rp(rp, val, relval)	__put_user_unaligned(val, rp)
 #define	flat_get_relocate_addr(rel)		(rel)
 #define	flat_set_persistent(relval, p)		0
 

rp is a user space reloc pointer therefore it should use user space 
accessors.  That's all there is to the arch specific part.  Pending your 
agreement with the above, everyone is fine with the series.


Nicolas

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web