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Commit 5a3b4e80 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Chris Metcalf
Browse files

tile/elf: reorganize notify_exec() 



In the future mm->exe_file will be done without mmap_sem
serialization, thus isolate and reorganize the tile elf
code to make the transition easier. Good users will, make
use of the more standard get_mm_exe_file(), requiring only
holding the mmap_sem to read the value, and relying on reference
counting to make sure that the exe file won't dissappear
underneath us.

The visible effects of this patch are:

   o We now take and drop the mmap_sem more often. Instead of
     just in arch_setup_additional_pages(), we also do it in:

     1) get_mm_exe_file()
     2) to get the mm->vm_file and notify the simulator.

    [Note that 1) will disappear once we change the locking
     rules for exe_file.]

   o We avoid getting a free page and doing d_path() while
     holding the mmap_sem. This requires reordering the checks.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarChris Metcalf <cmetcalf@ezchip.com>
parent 89067c2d

arch/tile/mm/elf.c

+29 −18
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/binfmts.h>

#include <linux/compat.h>

#include <linux/mman.h>

#include <linux/file.h>

#include <linux/elf.h>

#include <asm/pgtable.h>

#include <asm/pgalloc.h>
@@ -39,30 +40,34 @@ static void sim_notify_exec(const char *binary_name) 


static int notify_exec(struct mm_struct *mm)

{

	int ret = 0;

	char *buf, *path;

	struct vm_area_struct *vma;

	struct file *exe_file;



	if (!sim_is_simulator())

		return 1;



	if (mm->exe_file == NULL)

		return 0;



	for (vma = current->mm->mmap; ; vma = vma->vm_next) {

		if (vma == NULL)

			return 0;

		if (vma->vm_file == mm->exe_file)

			break;

	}



	buf = (char *) __get_free_page(GFP_KERNEL);

	if (buf == NULL)

		return 0;



	path = d_path(&mm->exe_file->f_path, buf, PAGE_SIZE);

	if (IS_ERR(path)) {

		free_page((unsigned long)buf);

		return 0;

	exe_file = get_mm_exe_file(mm);

	if (exe_file == NULL)

		goto done_free;



	path = d_path(&exe_file->f_path, buf, PAGE_SIZE);

	if (IS_ERR(path))

		goto done_put;



	down_read(&mm->mmap_sem);

	for (vma = current->mm->mmap; ; vma = vma->vm_next) {

		if (vma == NULL) {

			up_read(&mm->mmap_sem);

			goto done_put;

		}

		if (vma->vm_file == exe_file)

			break;

	}



	/*
@@ -80,14 +85,20 @@ static int notify_exec(struct mm_struct *mm) 
			__insn_mtspr(SPR_SIM_CONTROL,

				     (SIM_CONTROL_DLOPEN

				      | (c << _SIM_CONTROL_OPERATOR_BITS)));

			if (c == '\0')

			if (c == '\0') {

				ret = 1; /* success */

				break;

			}

		}

	}

	up_read(&mm->mmap_sem);



	sim_notify_exec(path);

done_put:

	fput(exe_file);

done_free:

	free_page((unsigned long)buf);

	return 1;

	return ret;

}



/* Notify a running simulator, if any, that we loaded an interpreter. */
@@ -109,8 +120,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, 
	struct mm_struct *mm = current->mm;

	int retval = 0;



	down_write(&mm->mmap_sem);



	/*

	 * Notify the simulator that an exec just occurred.

	 * If we can't find the filename of the mapping, just use
@@ -119,6 +128,8 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, 
	if (!notify_exec(mm))

		sim_notify_exec(bprm->filename);



	down_write(&mm->mmap_sem);



	retval = setup_vdso_pages();



#ifndef __tilegx__