[Patch 4/21] Make fill_psinfo generic

[Suzuki K. Poulose]

fill_psinfo() fills the NT_PRPSINFO note for the core. NT_PRPSINFO stores the 
command line of the process, which is stored at from mm->arg_start. Make 
fill_psinfo reusable by supporting other tasks. Use access_process_vm() to read 
the command line args for non-current task. 

Signed-off-by: Suzuki K. Poulose <suzuki@xxxxxxxxxx>
---
 fs/binfmt_elf.c |   17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

Index: linux-2.6.36-rc7/fs/binfmt_elf.c
===================================================================
--- linux-2.6.36-rc7.orig/fs/binfmt_elf.c
+++ linux-2.6.36-rc7/fs/binfmt_elf.c
@@ -1211,9 +1211,20 @@ static int fill_psinfo(struct elf_prpsin
 	len = mm->arg_end - mm->arg_start;
 	if (len >= ELF_PRARGSZ)
 		len = ELF_PRARGSZ-1;
-	if (copy_from_user(&psinfo->pr_psargs,
-		           (const char __user *)mm->arg_start, len))
-		return -EFAULT;
+	/*
+	 * If we are dumping core for "another task"
+	 * we can't use copy_from_user().
+	 */
+	if (p->group_leader == current->group_leader) {
+		if (copy_from_user(&psinfo->pr_psargs,
+			           (const char __user *)mm->arg_start, len))
+			return -EFAULT;
+	} else {
+		int bytes = access_process_vm(p, mm->arg_start,
+						&psinfo->pr_psargs, len, 0);
+		if (bytes != len)
+			return -EFAULT;
+	}
 	for(i = 0; i < len; i++)
 		if (psinfo->pr_psargs[i] == 0)
 			psinfo->pr_psargs[i] = ' ';
--
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