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MPX includes two separate "extended state components". There is
no real need to have an 'mpx_struct' because we never really
manage the states together.
We also separate out the actual data in 'mpx_bndcsr_state' from
the padding. We will shortly be checking the state sizes
against our structures and need them to match. For consistency,
we also ensure to prefix these types with 'mpx_'.
Lastly, we add some comments to mirror some of the descriptions
in the Intel documents (SDM) of the various state components.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: dave@sr71.net
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150902233129.384B73EB@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Bounds tables are a significant consumer of memory. It is
important to know when they are being allocated. Add a trace
point to trace whenever an allocation occurs and also its
virtual address.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.EC23A93E@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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There are two different events being traced here. They are
doing similar things so share a trace "EVENT_CLASS" and are
presented together.
1. Trace when MPX is zapping pages "mpx_unmap_zap":
When MPX can not free an entire bounds table, it will
instead try to zap unused parts of a bounds table to free
the backing memory. This decreases RSS (resident set
size) without decreasing the virtual space allocated
for bounds tables.
2. Trace attempts to find bounds tables "mpx_unmap_search":
This event traces any time we go looking to unmap a
bounds table for a given virtual address range. This is
useful to ensure that the kernel actually "tried" to free
a bounds table versus times it succeeded in finding one.
It might try and fail if it realized that a table was
shared with an adjacent VMA which is not being unmapped.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.B9D2468B@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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There are two basic things that can happen as the result of
a bounds exception (#BR):
1. We allocate a new bounds table
2. We pass up a bounds exception to userspace.
This patch adds a trace point for the case where we are
passing the exception up to userspace with a signal.
We are also explicit that we're printing out the inverse of
the 'upper' that we encounter. If you want to filter, for
instance, you need to ~ the value first. The reason we do
this is because of how 'upper' is stored in the bounds table.
If a pointer's range is:
0x1000 -> 0x2000
it is stored in the bounds table as (32-bits here for brevity):
lower: 0x00001000
upper: 0xffffdfff
That is so that an all 0's entry:
lower: 0x00000000
upper: 0x00000000
corresponds to the "init" bounds which store a *range* of:
0x00000000 -> 0xffffffff
That is, by far, the common case, and that lets us use the
zero page, or deduplicate the memory, etc... The 'upper'
stored in the table is gibberish to print by itself, so we
print ~upper to get the *actual*, logical, human-readable
value printed out.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.027BB9B0@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This is the first in a series of MPX tracing patches.
I've found these extremely useful in the process of
debugging applications and the kernel code itself.
This exception hooks in to the bounds (#BR) exception
very early and allows capturing the key registers which
would influence how the exception is handled.
Note that bndcfgu/bndstatus are technically still
64-bit registers even in 32-bit mode.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.5FE2619A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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