Commit Graph

3 Commits

Author SHA1 Message Date
Linus Torvalds
96d4f267e4 Remove 'type' argument from access_ok() function
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-03 18:57:57 -08:00
Nickhu
c8b3446170 nds32: Add perf call-graph support.
The perf call-graph option can trace the callchain
between functions. This commit add the perf callchain
for nds32. There are kerenl callchain and user callchain.
The kerenl callchain can trace the function in kernel
space. There are two type for user callchain. One for the
'optimize for size' config is set, and another one for the
config is not set. The difference between two types is that
the index of frame-pointer in user stack is not the same.

For example:
	With optimize for size:
		User Stack:
			---------
			|   lp	|
			---------
			|	gp	|
			---------
			|	fp	|

	Without optimize for size:
		User Stack:
		1. non-leaf function:
			---------
			|	lp	|
			---------
			|	fp	|

		2. leaf	function:
			---------
			|	fp	|

Signed-off-by: Nickhu <nickhu@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
2018-11-06 18:01:40 +08:00
Nickhu
ebd09753b5 nds32: Perf porting
This is the commit that porting the perf for nds32.

1.Raw event:
	The raw events start with 'r'.
		Usage:
			perf stat -e rXYZ ./app
			X: the index of performance counter.
			YZ: the index(convert to hexdecimal) of events

		Example:
			'perf stat -e r101 ./app' means the counter 1 will count the instruction
		event.

		The index of counter and events can be found in
		"Andes System Privilege Architecture Version 3 Manual".

Or you can perform the 'perf list' to find the symbolic name of raw events.

2.Perf mmap2:

	Fix unexpected perf mmap2() page fault

	When the mmap2() called by perf application,
	you will encounter such condition:"failed to write."
	With return value -EFAULT

	This is due to the page fault caused by "reading" buffer
	from the mapped legal address region to write to the descriptor.
	The page_fault handler will get a VM_FAULT_SIGBUS return value,
	which should not happens here.(Due to this is a read request.)

	You can refer to kernel/events/core.c:perf_mmap_fault(...)
	If "(vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))" is evaluated
	as true, you will get VM_FAULT_SIGBUS as return value.

	However, this is not an write request. The flags which indicated
	why the page fault happens is wrong.

	Furthermore, NDS32 SPAv3 is not able to detect it is read or write.
	It only know  either it is instruction fetch or data access.

	Therefore, by removing the wrong flag assignment(actually, the hardware
	is not able to show the reason), we can fix this bug.

3.Perf multiple events map to same counter.

	When there are multiple events map to the same counter, the counter
	counts inaccurately. This is because each counter only counts one event
	in the same time.
	So when there are multiple events map to same counter, they have to take
	turns in each context.

	There are two solution:
	1. Print the error message when multiple events map to the same counter.
	But print the error message would let the program hang in loop. The ltp
	(linux test program) would be failed when the program hang in loop.

	2. Don't print the error message, the ltp would pass. But the user need to
	have the knowledge that don't count the events which map to the same
	counter, or the user will get the inaccurate results.

	We choose method 2 for the solution

Signed-off-by: Nickhu <nickhu@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
2018-11-06 18:01:40 +08:00