diff options
| author | Miod Vallat <miod@cvs.openbsd.org> | 2013-08-26 21:38:10 +0000 |
|---|---|---|
| committer | Miod Vallat <miod@cvs.openbsd.org> | 2013-08-26 21:38:10 +0000 |
| commit | e9f4bf1da1af81716733684468d927489693c23c (patch) | |
| tree | cefe9ea0aad52683d7075fedab912e36a9e15471 /lib | |
| parent | d3f9c59d503b5b2c53f52910f4a5969042fa5fa9 (diff) | |
Use %r27 as the thread control block pointer, allowing for __get_tcb() calls
in libpthread to be optimized away.
While there, follow DG/UX's example of using more than one register for thread
purposes (after all, the ABI reserves four of them), and also use %r26 to store
a pointer to the current thread's errno.
Since it is not possible to initialize %r26 at thread creation without
intrusive and potentially race-prone changes, have __tfork() reset %r26 to
zero, and libpthread's __cerror lazy initialize it. As soon as %r26 is nonzero,
it will be used instead of calling __errno().
This means that binaries linked against HEAD libpthread need to run on HEAD
kernels, and we are belatedly jumping on the 64-bit time_t bump (since there
are no 64-bit time_t m88k snapshots yet).
Joint work with guenther@; "Your love of asm is sick and wrong, and yet
beautiful." and ok guenther@
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/librthread/arch/m88k/cerror.S | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/lib/librthread/arch/m88k/cerror.S b/lib/librthread/arch/m88k/cerror.S index fecea2caa09..d31dc807c50 100644 --- a/lib/librthread/arch/m88k/cerror.S +++ b/lib/librthread/arch/m88k/cerror.S @@ -1,4 +1,4 @@ -/* $OpenBSD: cerror.S,v 1.4 2013/01/27 09:56:05 miod Exp $ */ +/* $OpenBSD: cerror.S,v 1.5 2013/08/26 21:38:08 miod Exp $ */ /*- * Copyright (c) 1990 The Regents of the University of California. @@ -37,7 +37,16 @@ .globl _C_LABEL(__errno) +/* + * long long __cerror(register_t errcode) + * stores `errcode' into the current thread's errno variable, and returns + * -1LL. + */ + ASENTRY(__cerror) + /* if %r26 has been initialized, don't bother setting up a frame */ + bcnd ne0, %r26, has_r26 + subu %r31,%r31,16 st %r25,%r0,%r31 st %r1,%r31,4 @@ -48,13 +57,16 @@ ASENTRY(__cerror) bsr.n _C_LABEL(__errno) #endif or %r25,%r0,%r2 - st %r25,%r0,%r2 - - subu %r2,%r0,1 - or %r3, %r0, %r2 + or %r26,%r0,%r2 /* save errno ptr */ + or %r2,%r0,%r25 /* and restore errno value */ ld %r1,%r31,4 ld %r25,%r0,%r31 + addu %r31,%r31,16 + +has_r26: + st %r2,%r0,%r26 + subu %r2,%r0,1 jmp.n %r1 - addu %r31,%r31,16 + or %r3, %r0, %r2 END(__cerror) |