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New function to check if the page is readable before reading. Noop on

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Sat Apr 23 17:49:33 2005  Søren Sandmann  <sandmann@redhat.com>

	* sysprof-module.c (page_readable): New function to check if the
	page is readable before reading. Noop on kernel <= 2.6.11

	* sysprof-module.c (get_mm, put_mm): New functions to confine
	#ifdefs.
This commit is contained in:
Søren Sandmann
2005-04-23 21:53:16 +00:00
committed by Søren Sandmann Pedersen
parent 7b67e2c6b9
commit 753eb9378b
3 changed files with 71 additions and 19 deletions
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13
ChangeLog
View File

@ -1,3 +1,16 @@
Sat Apr 23 17:49:33 2005 Søren Sandmann <sandmann@redhat.com>
* sysprof-module.c (page_readable): New function to check if the
page is readable before reading. Noop on kernel <= 2.6.11
* sysprof-module.c (get_mm, put_mm): New functions to confine
#ifdefs.
Sat Apr 23 17:48:22 2005 Søren Sandmann <sandmann@redhat.com>
* Makefile (MODCFLAGS): Disable optimization as I suspect
the oops is related to miscompilation.
Fri Apr 22 00:09:16 2005 Soeren Sandmann <sandmann@redhat.com>
* sysprof-module.c (read_user_space): On >= 2.6.11 check that the

2
Makefile
View File

@ -14,7 +14,7 @@ BINARY := sysprof
MODULE := sysprof-module
KDIR := /lib/modules/$(shell uname -r)/build
INCLUDE := -isystem $(KDIR)/include
MODCFLAGS := -O2 -DMODULE -D__KERNEL__ -Wall ${INCLUDE}
MODCFLAGS := -DMODULE -D__KERNEL__ -Wall ${INCLUDE}
MODULE := sysprof-module
all: check $(BINARY) $(MODULE).o

75
sysprof-module.c
View File

@ -72,29 +72,50 @@ struct userspace_reader
* Source/target buffer must be kernel space,
* Do not walk the page table directly, use get_user_pages
*/
static struct mm_struct *
get_mm (struct task_struct *tsk)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,9)
struct mm_struct *mm;
task_lock (tsk);
mm = tsk->mm;
task_unlock (tsk);
return mm;
#else
return get_task_mm (tsk);
#endif
}
static void
put_mm (struct mm_struct *mm)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,9)
mmput(mm);
#endif
}
static int
x_access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
x_access_process_vm (struct task_struct *tsk,
unsigned long addr,
void *buf, int len, int write)
{
struct mm_struct *mm;
struct vm_area_struct *vma;
struct page *page;
void *old_buf = buf;
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,9)
task_lock (tsk);
mm = tsk->mm;
task_unlock (tsk);
#else
mm = get_task_mm (tsk);
#endif
mm = get_mm (tsk);
if (!mm)
return 0;
down_read(&mm->mmap_sem);
/* ignore errors, just check how much was sucessfully transfered */
while (len) {
while (len)
{
int bytes, ret, offset;
void *maddr;
@ -131,9 +152,7 @@ x_access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int
}
up_read(&mm->mmap_sem);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,9)
mmput(mm);
#endif
put_mm (mm);
return buf - old_buf;
}
@ -150,6 +169,27 @@ init_userspace_reader (userspace_reader *reader,
return 1;
}
static int
page_readable (userspace_reader *reader, unsigned long address)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION (2,6,11)
struct mm_struct *mm;
int result = 1;
mm = get_mm (reader->task);
if (!mm)
return 0;
if (!check_user_page_readable (reader->task->mm, address))
result = 0;
put_mm (mm);
return result;
#endif
}
static int
read_user_space (userspace_reader *reader,
unsigned long address,
@ -158,11 +198,10 @@ read_user_space (userspace_reader *reader,
unsigned long cache_address = reader->cache_address;
int index, r;
if (!cache_address || cache_address != (address & PAGE_MASK)) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION (2,6,11)
if (!check_user_page_readable (reader->task->mm, address))
if (!cache_address || cache_address != (address & PAGE_MASK))
{
if (!page_readable (reader, address))
return 0;
#endif
cache_address = address & PAGE_MASK;
@ -240,7 +279,7 @@ generate_stack_trace(struct task_struct *task,
if (init_userspace_reader (&reader, task))
{
while (i < SYSPROF_MAX_ADDRESSES &&
read_frame (&reader, addr, &frame) &&
read_frame (&reader, addr, &frame) &&
addr < START_OF_STACK && addr >= regs->esp)
{
trace->addresses[i++] = (void *)frame.return_address;