mirror of https://github.com/torvalds/linux.git
Some of our TM (Transactional Memory) tests, list "r1" (the stack
pointer) as a clobbered register.
GCC >= 9 doesn't accept this, and the build breaks:
ptrace-tm-spd-tar.c: In function 'tm_spd_tar':
ptrace-tm-spd-tar.c:31:2: error: listing the stack pointer register 'r1' in a clobber list is deprecated [-Werror=deprecated]
31 | asm __volatile__(
| ^~~
ptrace-tm-spd-tar.c:31:2: note: the value of the stack pointer after an 'asm' statement must be the same as it was before the statement
We do have some fairly large inline asm blocks in these tests, and
some of them do change the value of r1. However they should all return
to C with the value in r1 restored, so I think it's legitimate to say
r1 is not clobbered.
As Segher points out, the r1 clobbers may have been added because of
the use of `or 1,1,1`, however that doesn't actually clobber r1.
Segher also points out that some of these tests do clobber LR, because
they call functions, and that is not listed in the clobbers, so add
that where appropriate.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191029095324.14669-1-mpe@ellerman.id.au
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| block | ||
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| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.