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, 12 insertions, 6 deletions

diff --git a/sys/powerpc/powerpc/mmu_if.m b/sys/powerpc/powerpc/mmu_if.m
index 4a5a37c456c5..5b8ba14d6898 100644
--- a/sys/powerpc/powerpc/mmu_if.m
+++ b/sys/powerpc/powerpc/mmu_if.m
@@ -789,15 +789,21 @@ METHOD boolean_t dev_direct_mapped {
 
 
 /**
- * @brief Evaluate if a physical page has an executable mapping
+ * @brief Enforce instruction cache coherency. Typically called after a
+ * region of memory has been modified and before execution of or within
+ * that region is attempted. Setting breakpoints in a process through
+ * ptrace(2) is one example of when the instruction cache needs to be
+ * made coherent.
  *
- * @param _pg		physical page
- *
- * @retval bool		TRUE if a physical mapping exists for the given page.
+ * @param _pm		the physical map of the virtual address
+ * @param _va		the virtual address of the modified region
+ * @param _sz		the size of the modified region
  */
-METHOD boolean_t page_executable {
+METHOD void sync_icache {
 	mmu_t		_mmu;
-	vm_page_t	_pg;
+	pmap_t		_pm;
+	vm_offset_t	_va;
+	vm_size_t	_sz;
 };