Unpaired calling of probe_hcall_entry and probe_hcall_exit might happen
as following, which could cause incorrect preempt count.
__trace_hcall_entry => trace_hcall_entry -> probe_hcall_entry =>
get_cpu_var => preempt_disable
__trace_hcall_exit => trace_hcall_exit -> probe_hcall_exit =>
put_cpu_var => preempt_enable
where:
A => B and A -> B means A calls B, but
=> means A will call B through function name, and B will definitely be
called.
-> means A will call B through function pointer, so B might not be
called if the function pointer is not set.
So error happens when only one of probe_hcall_entry and probe_hcall_exit
get called during a hcall.
This patch tries to move the preempt count operations from
probe_hcall_entry and probe_hcall_exit to its callers.
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CC: stable@kernel.org [v2.6.32+]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Unnecessary cast from void* in assignment.
Signed-off-by: matt mooney <mfm@muteddisk.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Commit 38516ab59f ("tracing: Let
tracepoints have data passed to tracepoint callbacks") requires this
fixup to the powerpc code.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tb_total and purr_total values reported via the hcall_stats code
should be cumulative, rather than being replaced by the latest delta tb
or purr value.
Tested-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
While most users of the hcall tracepoints will only want the opcode
and return code, some will want all the arguments. To avoid the
complexity of using varargs we pass a pointer to the register save
area, which contains all the arguments.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Add hcall_entry and hcall_exit tracepoints. This replaces the inline
assembly HCALL_STATS code and converts it to use the new tracepoints.
To keep the disabled case as quick as possible, we embed a status word
in the TOC so we can get at it with a single load. By doing so we
keep the overhead at a minimum. Time taken for a null hcall:
No tracepoint code: 135.79 cycles
Disabled tracepoints: 137.95 cycles
For reference, before this patch enabling HCALL_STATS resulted in a null
hcall of 201.44 cycles!
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Make all seq_operations structs const, to help mitigate against
revectoring user-triggerable function pointers.
This is derived from the grsecurity patch, although generated from scratch
because it's simpler than extracting the changes from there.
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many struct file_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.
[akpm@osdl.org: sparc64 fix]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There were a few issues with the HCALL_STATS code:
- PURR cpu feature checks were backwards
- We iterated one entry off the end of the hcall_stats array
- Remove dead update_hcall_stats() function prototype
I noticed one thing while debugging, and that is we call H_ENTER (to set
up the MMU hashtable in early init) before we have done the cpu fixups.
This means we will execute the PURR SPR reads even on a CPU that isnt
capable of it. I wonder if we can move the CPU feature fixups earlier.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
The following patches reduce the size of the VFS inode structure by 28 bytes
on a UP x86. (It would be more on an x86_64 system). This is a 10% reduction
in the inode size on a UP kernel that is configured in a production mode
(i.e., with no spinlock or other debugging functions enabled; if you want to
save memory taken up by in-core inodes, the first thing you should do is
disable the debugging options; they are responsible for a huge amount of bloat
in the VFS inode structure).
This patch:
The filesystem or device-specific pointer in the inode is inside a union,
which is pretty pointless given that all 30+ users of this field have been
using the void pointer. Get rid of the union and rename it to i_private, with
a comment to explain who is allowed to use the void pointer. This is just a
cleanup, but it allows us to reuse the union 'u' for something something where
the union will actually be used.
[judith@osdl.org: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Judith Lebzelter <judith@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add instrumentation for hypervisor calls on pseries. Call statistics
include number of calls, wall time and cpu cycles (if available) and
are made available via debugfs. Instrumentation code is behind the
HCALL_STATS config option and has no impact if not enabled.
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Al Viro