Date: Wed, 30 Jan 2002 09:47:13 -0800 (PST) From: Bruce Evans <bde@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/i386/i386 machdep.c Message-ID: <200201301747.g0UHlEs29212@freefall.freebsd.org>
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bde 2002/01/30 09:47:13 PST
Modified files:
sys/i386/i386 machdep.c
Log:
Cleaned up the 0ldSiG magic check before removing it. Just use fuword()
to fetch the magic word instead of useracc() plus a direct access.
This is more efficient as well as simpler and less incorrect:
- it was inefficent because useracc() takes much longer than just
accessing the data using a correct access method, at least on i386's.
- it was incorrect because direct access is incorrect unless the address
has been mapped. This and nearby direct accesses are mostly handled
better for other arches because they have to be (direct accesses don't
work).
- using magic in sigreturn is still fundamentally broken because false
matches are possible. On i386's, a false match occurs when %eip in a
new signal context happens to equal the magic value. This is not
handled better for other arches.
Revision Changes Path
1.489 +8 -13 src/sys/i386/i386/machdep.c
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