Re: [patch 1/4] powerpc: fix for OProfile callgraph for Power 64 bit user apps
On Thu, 2008-05-15 at 13:58 +1000, Paul Mackerras wrote: Michael Ellerman writes: __copy_from_user_inatomic() accepts any value for n, it just has a special case for 1, 2, 4 and 8 - but it should still work for other values. There is a bug in __copy_from_user_inatomic that http://patchwork.ozlabs.org/linuxppc/patch?id=18418 fixes, and I'm about to send that Linus-wards. Carl, to what extent does that fix eliminate the need for the changes in your patch? Paul. Paul: I will have to apply the above mentioned patch to see if it fixes the issue. What I found was when the original code tried to copy three unsigned long into stack_frame[3], i.e. 24 bytes my system consistently failed. The comment about 48 bytes is a note that is all that is guaranteed to be there according to the API. I found by restricting the copy to the values in the case statement, things worked. Carl Love ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
[patch 1/4] powerpc: fix for OProfile callgraph for Power 64 bit user apps
From: Carl Love [EMAIL PROTECTED]
Fix the 64 bit user code backtrace which currently may hang the system.
Signed-off-by: Carl Love [EMAIL PROTECTED]
Cc: Maynard Johnson [EMAIL PROTECTED]
Signed-off-by: Andrew Morton [EMAIL PROTECTED]
---
arch/powerpc/oprofile/backtrace.c | 33 ++--
1 file changed, 27 insertions(+), 6 deletions(-)
diff -puN
arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
arch/powerpc/oprofile/backtrace.c
---
a/arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
+++ a/arch/powerpc/oprofile/backtrace.c
@@ -53,19 +53,40 @@ static unsigned int user_getsp32(unsigne
#ifdef CONFIG_PPC64
static unsigned long user_getsp64(unsigned long sp, int is_first)
{
- unsigned long stack_frame[3];
+ unsigned long stk_frm_lr;
+ unsigned long stk_frm_sp;
+ unsigned long size;
+
+ /* Issue the __copy_from_user_inatomic() third argument currently
+* only takes sizes 1, 2, 4 or 8 bytes. Don't read more then the
+* first 48 bytes of the stack frame. That is all that is
+* guaranteed to exist. Reading more may cause the system to hang.
+*
+* 64 bit stack frame layout:
+* 0-7 bytes is the pointer to previous stack
+* 8-15 bytes condition register save area
+* 16-23 bytes link register save area
+*/
+ size = sizeof(unsigned long);
+ if (!access_ok(VERIFY_READ, (void __user *)sp, size))
+ return 0;
- if (!access_ok(VERIFY_READ, (void __user *)sp, sizeof(stack_frame)))
+ if (__copy_from_user_inatomic(stk_frm_sp, (void __user *)sp,
+ size))
return 0;
- if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
- sizeof(stack_frame)))
+ /* get the LR from the user stack */
+ if (!access_ok(VERIFY_READ, (void __user *)(sp+16), size))
+ return 0;
+
+ if (__copy_from_user_inatomic(stk_frm_lr, (void __user *)(sp+16),
+ size))
return 0;
if (!is_first)
- oprofile_add_trace(STACK_LR64(stack_frame));
+ oprofile_add_trace(stk_frm_lr);
- return STACK_SP(stack_frame);
+ return stk_frm_sp;
}
#endif
_
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Re: [patch 1/4] powerpc: fix for OProfile callgraph for Power 64 bit user apps
On Wed, 2008-05-14 at 16:12 -0700, [EMAIL PROTECTED] wrote:
From: Carl Love [EMAIL PROTECTED]
Fix the 64 bit user code backtrace which currently may hang the system.
Signed-off-by: Carl Love [EMAIL PROTECTED]
Cc: Maynard Johnson [EMAIL PROTECTED]
Signed-off-by: Andrew Morton [EMAIL PROTECTED]
Hi Carl,
I'm a bit confused by this change ..
diff -puN
arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
arch/powerpc/oprofile/backtrace.c
---
a/arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
+++ a/arch/powerpc/oprofile/backtrace.c
@@ -53,19 +53,40 @@ static unsigned int user_getsp32(unsigne
#ifdef CONFIG_PPC64
static unsigned long user_getsp64(unsigned long sp, int is_first)
{
- unsigned long stack_frame[3];
+ unsigned long stk_frm_lr;
+ unsigned long stk_frm_sp;
+ unsigned long size;
+
+ /* Issue the __copy_from_user_inatomic() third argument currently
+ * only takes sizes 1, 2, 4 or 8 bytes. Don't read more then the
+ * first 48 bytes of the stack frame. That is all that is
+ * guaranteed to exist. Reading more may cause the system to hang.
__copy_from_user_inatomic() accepts any value for n, it just has a
special case for 1, 2, 4 and 8 - but it should still work for other
values.
The old code copied 24 bytes from sp, and the new code copies 8 bytes
from sp and 8 bytes from sp + 16 - so I don't see where the 48 bytes
comes in to it?
Also the comment is a little hard to parse, I think you mean Issue:
the .., but I read Issue as a verb in that sentence. And Don't read
more then should be than.
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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Re: [patch 1/4] powerpc: fix for OProfile callgraph for Power 64 bit user apps
Michael Ellerman writes: __copy_from_user_inatomic() accepts any value for n, it just has a special case for 1, 2, 4 and 8 - but it should still work for other values. There is a bug in __copy_from_user_inatomic that http://patchwork.ozlabs.org/linuxppc/patch?id=18418 fixes, and I'm about to send that Linus-wards. Carl, to what extent does that fix eliminate the need for the changes in your patch? Paul. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
