Le 10/01/2018 à 09:43, David Hildenbrand a écrit : > On 09.01.2018 00:10, Laurent Vivier wrote: >> The MC68040 MMU provides the size of the access that >> triggers the page fault. >> >> This size is set in the Special Status Word which >> is written in the stack frame of the access fault >> exception. >> >> So we need the size in m68k_cpu_unassigned_access() and >> m68k_cpu_handle_mmu_fault(). >> >> To be able to do that, this patch modifies the prototype of >> handle_mmu_fault handler, tlb_fill() and probe_write(). >> do_unassigned_access() already includes a size parameter. >> >> This patch also updates handle_mmu_fault handlers and >> tlb_fill() of all targets (only parameter, no code change). >> > > There are a couple of places where you use "1" (when no other size is > available). e.g. in get_page_addr_code(). > > Wonder if that's the right thing to do - are there any architectures > that e.g. always fetch at least 2 bytes in these conditions? >
It's a good question. "1" is passed to probe_write() and tlb_fill() and handle_mmu_fault(). probe_write() calls tlb_fill(), and tlb_fill() calls machine handle_mmu_fault handler. As no existing handle_mmu_fault takes care of the access size, I think passing 1 and ignoring it doesn't change the existing behavior. probe_write() is used to check if a page is writable, and none of the callers is guessing the write can cross a page boundary, so 1 is the good value in this case. get_page_addr_code() is the only user of tlb_fill() with 1. and callers of get_page_addr_code() never guess the code address can run across a page boundary. Some of them calls get_page_addr_code() a second time to check this case. So I think using 1 is good solution, but perhaps the code could be improved by adding the size parameter to get_page_addr_code(). My purpose was not to change the functions behavior, only to add the new parameter. So using "1" when the size is not obvious is a good solution to me. Thank you for your comment! Laurent
