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[Bug runtime/12341] New: deref()/store_deref() variations between arches
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: Wed, 22 Dec 2010 20:54:52 +0000
- Subject: [Bug runtime/12341] New: deref()/store_deref() variations between arches
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=12341
Summary: deref()/store_deref() variations between arches
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: runtime
AssignedTo: systemtap@sources.redhat.com
ReportedBy: dsmith@redhat.com
There is a different deref()/store_deref() macro in runtime/loc2c-runtime.h for
each arch.
For i386/x86_64, deref() calls the kernel's __get_user_asm(). store_deref()
calls the kernel's __put_user_asm().
For ia64, deref() calls the kernel's __get_user_size(). store_deref() calls
the kernel's __put_user_size().
For powerpc, deref() calls __stp_get_user_asm(), which is custom powerpc
assembly code (that looks almost identical to the kernel's __get_user_asm()).
store_deref() calls __stp_put_user_asm(), which is custom powerpc assembly
code.
For s390, deref() calls __stp_get_user_asm(), which is custom s390 assembly.
store_deref() calls __stp_put_user_asm(), which is custom s390 assembly.
It might be possible for all arches to use the kernel's own routines, instead
of having custom (powerpc/s390) assembly code. The
__get_user_size()/__put_user_size() routines might be the most attractive
choice (as the ia64 uses), since they know how handle all the different size
combinations.
(If __get_user_size()/__put_user_size() works for the i386, that could
eliminate the need for the i386 special version of kread/kwrite that can handle
64-bit values.)
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