o Introduce vm_sync_icache() for making the I-cache coherent with

    the memory or D-cache, depending on the semantics of the platform.
    vm_sync_icache() is basically a wrapper around pmap_sync_icache(),
    that translates the vm_map_t argumument to pmap_t.
o   Introduce pmap_sync_icache() to all PMAP implementation. For powerpc
    it replaces the pmap_page_executable() function, added to solve
    the I-cache problem in uiomove_fromphys().
o   In proc_rwmem() call vm_sync_icache() when writing to a page that
    has execute permissions. This assures that when breakpoints are
    written, the I-cache will be coherent and the process will actually
    hit the breakpoint.
o   This also fixes the Book-E PMAP implementation that was missing
    necessary locking while trying to deal with the I-cache coherency
    in pmap_enter() (read: mmu_booke_enter_locked).

The key property of this change is that the I-cache is made coherent
*after* writes have been done. Doing it in the PMAP layer when adding
or changing a mapping means that the I-cache is made coherent *before*
any writes happen. The difference is key when the I-cache prefetches.

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index b8803af..88a5b89 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -327,6 +327,10 @@ proc_rwmem(struct proc *p, struct uio *uio)
 		 */
 		error = uiomove_fromphys(&m, page_offset, len, uio);
 
+		/* Make the I-cache coherent for breakpoints. */
+		if (!error && writing && (out_prot & VM_PROT_EXECUTE))
+			vm_sync_icache(map, uva, len);
+
 		/*
 		 * Release the page.
 		 */