Kernel space needs very little in the way of BTC maintanence as most
mappings which are created and destroyed are non-executable, and so
could never enter the instruction stream.
The case which does warrant BTC maintanence is when a module is loaded.
This creates a new executable mapping, but at that point the pages have
not been initialized with code and data, so at that point they contain
unpredictable information. Invalidating the BTC at this stage serves
little useful purpose.
Before we execute module code, we call flush_icache_range(), which deals
with the BTC maintanence requirements. This ensures that we have a BTC
maintanence operation before we execute code via the newly created
mapping.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arm is placing some code in the .text.init section, but it does not
reference that section in its linker scripts.
This change moves this code from the .text.init section to the
.init.text section, which is presumably where it belongs.
Signed-off-by: Tim Abbott <tabbott@mit.edu>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The architecture specification states that TLB operations are
guaranteed to be complete only after the execution of a DSB (Data
Synchronisation Barrier, former Data Write Barrier or Drain Write
Buffer). The branch target cache invalidation is also needed. The ISB
(Instruction Synchronisation Barrier, formerly Prefetch Flush) is
needed unless there will be a return from exception before the
corresponding mapping is used (i.e. user mappings).
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Catalin Marinas
Chapter B2.7.3 in the latest ARM ARM (with v6 information) states that
the completion of a TLB maintenance operation is only guaranteed by
the execution of a DSB (Data Syncronization Barrier, formerly Data
Write Barrier or Drain Write Buffer).
Note that a DSB is only needed in the flush_tlb_kernel_* functions
since the completion is guaranteed by a mode change (i.e. switching
back to user mode) for the flush_tlb_user_* functions.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Russell King