Hi!
E.g. on x86-64,
NEW_AUX_ENT(AT_UID, (elf_addr_t) current->uid);
NEW_AUX_ENT(AT_EUID, (elf_addr_t) current->euid);
NEW_AUX_ENT(AT_GID, (elf_addr_t) current->gid);
NEW_AUX_ENT(AT_EGID, (elf_addr_t) current->egid);
results in 4 movq %gs:0,%rax instructions while one is completely
enough.
Anyone remembers why get_current function (on arches which define
current to get_current()) is not const and why on x86-64
the movq %%gs:0, %0 inline asm is volatile with "memory" clobber?
AFAIK current ought to be constant in any function with the exception of
schedule.
If the reason is kernel/sched.c, then IMHO it is certainly
worth making get_current const everywhere but in kernel/sched.c
(e.g. through special define in sched.c before any includes).
Jakub
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This archive was generated by hypermail 2b29 : Sat Mar 15 2003 - 22:00:34 EST