Messages in this thread | | | Date | Wed, 15 Dec 1999 22:19:42 -0700 | From | Richard Gooch <> | Subject | Re: [patch] fastcall-2.3.32-B6, SYSENTER/SYSEXIT support |
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Richard Guenther writes: > Richard Gooch writes: > > I propose a much simpler abstraction: set up a global page (which > > always appears at a fixed address in user-space), and set up a jump > > table. Have one jump vector per system call. That's the ABI. End of > > story. > > While I like the idea in general, a more generic solution would to > tell the dynamic linker about this page and have a global symbol > like __linux_ia32_entry and have it fixup the syscall entry addresses > at runtime. This way you could override the magic symbol with > LD_PRELOAD and implement strace and friends via a intermediate > jump table. > > You could switch from a jump-table to a destination-address-table > and have either indirect calls or let the dynamic linker fixup > direct calls by reading addresses (of course they have to have fixed > values after boot then...) from the global page - no indirect or > double jump penalty.
This doesn't affect the kernel. The kernel just provides the jump table in a known location. User-space can decide what to do with that. You can have your __linux_ia32_entry symbol or not, as you like.
Regards,
Richard.... Permanent: rgooch@atnf.csiro.au Current: rgooch@ras.ucalgary.ca
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