Perform an exec() class syscall with a suspended transaction.
This is a test for the bug we fixed in 8e96a87c54 ("powerpc/tm: Always
reclaim in start_thread() for exec() class syscalls").
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
[mpe: Fix build errors, use a single binary for the test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move have_htm_nosc() into a new tm.h, and add a new helper, have_htm()
which we'll use in the next patch.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When building against older kernel headers, currently the tm-syscall
test fails to build because PPC_FEATURE2_HTM_NOSC is not defined.
Tweak the test so that if PPC_FEATURE2_HTM_NOSC is not defined it still
builds, but prints a warning at run time and marks the test as skipped.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch changes the syscall handler to doom (tabort) active
transactions when a syscall is made and return very early without
performing the syscall and keeping side effects to a minimum (no CPU
accounting or system call tracing is performed). Also included is a
new HWCAP2 bit, PPC_FEATURE2_HTM_NOSC, to indicate this
behaviour to userspace.
Currently, the system call instruction automatically suspends an
active transaction which causes side effects to persist when an active
transaction fails.
This does change the kernel's behaviour, but in a way that was
documented as unsupported. It doesn't reduce functionality as
syscalls will still be performed after tsuspend; it just requires that
the transaction be explicitly suspended. It also provides a
consistent interface and makes the behaviour of user code
substantially the same across powerpc and platforms that do not
support suspended transactions (e.g. x86 and s390).
Performance measurements using
http://ozlabs.org/~anton/junkcode/null_syscall.c indicate the cost of
a normal (non-aborted) system call increases by about 0.25%.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Check that a syscall made during an active transaction will fail with
the correct failure code and that one made during a suspended
transaction will succeed.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
