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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-07-05 09:01:13 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-07-19 11:44:06 +0100 |
| commit | 4348810a241a330d3d143d62d7c988ec8b2e6629 (patch) | |
| tree | 057e8799eb71e35702f39dc276bceb5d93567000 /arch/arm/mm/tlb-fa.S | |
| parent | eb96c925152fc289311e5d7e956b919e9b60ab53 (diff) | |
| download | linux-4348810a241a330d3d143d62d7c988ec8b2e6629.tar.gz | |
ARM: btc: avoid invalidating the branch target cache on kernel TLB maintanence
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>
Diffstat (limited to 'arch/arm/mm/tlb-fa.S')
| -rw-r--r-- | arch/arm/mm/tlb-fa.S | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/arm/mm/tlb-fa.S b/arch/arm/mm/tlb-fa.S index 9694f1f6f485..d887a31faaae 100644 --- a/arch/arm/mm/tlb-fa.S +++ b/arch/arm/mm/tlb-fa.S @@ -46,7 +46,6 @@ ENTRY(fa_flush_user_tlb_range) add r0, r0, #PAGE_SZ cmp r0, r1 blo 1b - mcr p15, 0, r3, c7, c5, 6 @ invalidate BTB mcr p15, 0, r3, c7, c10, 4 @ data write barrier mov pc, lr @@ -60,9 +59,8 @@ ENTRY(fa_flush_kern_tlb_range) add r0, r0, #PAGE_SZ cmp r0, r1 blo 1b - mcr p15, 0, r3, c7, c5, 6 @ invalidate BTB mcr p15, 0, r3, c7, c10, 4 @ data write barrier - mcr p15, 0, r3, c7, c5, 4 @ prefetch flush + mcr p15, 0, r3, c7, c5, 4 @ prefetch flush (isb) mov pc, lr __INITDATA |