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Changeset 38ff925 in mainline


Ignore:
Timestamp:
2011-11-28T21:51:44Z (10 years ago)
Author:
Jakub Jermar <jakub@…>
Branches:
lfn, master
Children:
481a9380
Parents:
40c8c17
Message:

Force kernel stacks to be allocated from the low-memory.

File:
1 edited

Legend:

Unmodified
Added
Removed
  • kernel/generic/src/proc/thread.c

    r40c8c17 r38ff925  
    173173#endif /* CONFIG_FPU */
    174174       
     175        /*
     176         * Allocate the kernel stack from the low-memory to prevent an infinite
     177         * nesting of TLB-misses when accessing the stack from the part of the
     178         * TLB-miss handler written in C.
     179         *
     180         * Note that low-memory is safe to be used for the stack as it will be
     181         * covered by the kernel identity mapping, which guarantees not to
     182         * nest TLB-misses infinitely (either via some hardware mechanism or
     183         * by the construciton of the assembly-language part of the TLB-miss
     184         * handler).
     185         *
     186         * This restriction can be lifted once each architecture provides
     187         * a similar guarantee, for example by locking the kernel stack
     188         * in the TLB whenever it is allocated from the high-memory and the
     189         * thread is being scheduled to run.
     190         */
     191        kmflags |= FRAME_LOWMEM;
     192        kmflags &= ~FRAME_HIGHMEM;
     193
    175194        thread->kstack = (uint8_t *) frame_alloc(STACK_FRAMES, FRAME_KA | kmflags);
    176195        if (!thread->kstack) {
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