Date: Tue, 27 Mar 2001 14:52:45 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: alpha@FreeBSD.org Subject: exception_return broken? Message-ID: <XFMail.010327145245.jhb@FreeBSD.org>
next in thread | raw e-mail | index | archive | help
While browsing sys/alpha/alpha/exception.s I had a little epiphany that might
explain the problems we are seeing with signals. First some quotes from
<machine/asm.h>:
/*
* LEAF
* Declare a global leaf function.
* A leaf function does not call other functions AND does not
* use any register that is callee-saved AND does not modify
* the stack pointer.
*/
...
/*
* NESTED
* Declare a (global) nested function
* A nested function calls other functions and needs
* therefore stack space to save/restore registers.
*/
Now look at exception_return in exception.s:
/*
* exception_return: return from trap, exception, or syscall
*/
LEAF(exception_return, 1) /* XXX should be NESTED */
br pv, Ler1
Ler1: LDGP(pv)
...
/* Handle any AST's or resched's. */
mov sp, a0 /* only arg is frame */
CALL(ast)
Lrestoreregs:
/* set the hae register if this process has specified a value */
ldq t0, GD_CURPROC(globalp)
beq t0, Lnohae
ldq t1, P_MD_FLAGS(t0)
and t1, MDP_HAEUSED
beq t1, Lnohae
ldq a0, P_MD_HAE(t0)
ldq pv, chipset + CHIPSET_WRITE_HAE
CALL((pv))
I think we should definitely make exception_return NESTED() as the XXX comment
indicates, but I'm not sure how to to easily do that, as NESTED() requires a
number of arguments for things like the frame size and bitmasks of used
registers.
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-alpha" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.010327145245.jhb>