diff options
| author | Robin Getz <robin.getz@analog.com> | 2008-01-27 15:38:44 +0800 |
|---|---|---|
| committer | Bryan Wu <bryan.wu@analog.com> | 2008-01-27 15:38:44 +0800 |
| commit | f53e86760e10abbe7ee98a5b3cb270fa6426fcdb (patch) | |
| tree | 739f681a136f7a6955328851db40e6a179a24865 | |
| parent | 326e96b92306b7af24a3608ec01156cba17a3fc1 (diff) | |
[Blackfin] arch: Add a note describing what is going on - no functional changes
Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
| -rw-r--r-- | arch/blackfin/mach-common/cplbmgr.S | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/blackfin/mach-common/cplbmgr.S b/arch/blackfin/mach-common/cplbmgr.S index 6f909cbfac7..faca1ab344d 100644 --- a/arch/blackfin/mach-common/cplbmgr.S +++ b/arch/blackfin/mach-common/cplbmgr.S @@ -75,6 +75,15 @@ ENTRY(_cplb_mgr) * from the configuration table. */ + /* A multi-word instruction can cross a page boundary. This means the + * first part of the instruction can be in a valid page, but the + * second part is not, and hence generates the instruction miss. + * However, the fault address is for the start of the instruction, + * not the part that's in the bad page. Therefore, we have to check + * whether the fault address applies to a page that is already present + * in the table. + */ + P4.L = LO(ICPLB_FAULT_ADDR); P4.H = HI(ICPLB_FAULT_ADDR); @@ -87,7 +96,7 @@ ENTRY(_cplb_mgr) R4 = [P4]; /* Get faulting address*/ R6 = 64; /* Advance past the fault address, which*/ R6 = R6 + R4; /* we'll use if we find a match*/ - R3 = ((16 << 8) | 2); /* Extract mask, bits 16 and 17.*/ + R3 = ((16 << 8) | 2); /* Extract mask, two bits at posn 16 */ R5 = 0; .Lisearch: @@ -125,7 +134,9 @@ ENTRY(_cplb_mgr) P4.L = LO(IMEM_CONTROL); P4.H = HI(IMEM_CONTROL); - /* disable cplbs */ + /* Turn off CPLBs while we work, necessary according to HRM before + * modifying CPLB descriptors + */ R5 = [P4]; /* Control Register*/ BITCLR(R5,ENICPLB_P); CLI R1; |