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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-07-05 09:01:13 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-07-19 11:44:06 +0100
commit4348810a241a330d3d143d62d7c988ec8b2e6629 (patch)
tree057e8799eb71e35702f39dc276bceb5d93567000 /arch/arm/mm/tlb-v6.S
parenteb96c925152fc289311e5d7e956b919e9b60ab53 (diff)
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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-v6.S')
-rw-r--r--arch/arm/mm/tlb-v6.S4
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/arm/mm/tlb-v6.S b/arch/arm/mm/tlb-v6.S
index 73d7d89..ffe06a6 100644
--- a/arch/arm/mm/tlb-v6.S
+++ b/arch/arm/mm/tlb-v6.S
@@ -54,7 +54,6 @@ ENTRY(v6wbi_flush_user_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, ip, c7, c5, 6 @ flush BTAC/BTB
mcr p15, 0, ip, c7, c10, 4 @ data synchronization barrier
mov pc, lr
@@ -83,9 +82,8 @@ ENTRY(v6wbi_flush_kern_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
mcr p15, 0, r2, c7, c10, 4 @ data synchronization barrier
- mcr p15, 0, r2, c7, c5, 4 @ prefetch flush
+ mcr p15, 0, r2, c7, c5, 4 @ prefetch flush (isb)
mov pc, lr
__INIT
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