ARM: 8191/1: decompressor: ensure I-side picks up relocated code

To speed up decompression, the decompressor sets up a flat, cacheable
mapping of memory. However, when there is insufficient space to hold
the page tables for this mapping, we don't bother to enable the caches
and subsequently skip all the cache maintenance hooks.

Skipping the cache maintenance before jumping to the relocated code
allows the processor to predict the branch and populate the I-cache
with stale data before the relocation loop has completed (since a
bootloader may have SCTLR.I set, which permits normal, cacheable
instruction fetches regardless of SCTLR.M).

This patch moves the cache maintenance check into the maintenance
routines themselves, allowing the v6/v7 versions to invalidate the
I-cache regardless of the MMU state.

Cc: <stable@vger.kernel.org>
Reported-by: Marc Carino <marc.ceeeee@gmail.com>
Tested-by: Julien Grall <julien.grall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 16 insertions, 4 deletions

diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 413fd94b5301..68be9017593d 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -397,8 +397,7 @@ dtb_check_done:
                 add     sp, sp, r6
 #endif
 
-                tst     r4, #1
-                bleq    cache_clean_flush
+                bl      cache_clean_flush
 
                 adr     r0, BSYM(restart)
                 add     r0, r0, r6
@@ -1047,6 +1046,8 @@ cache_clean_flush:
                 b       call_cache_fn
 
 __armv4_mpu_cache_flush:
+                tst     r4, #1
+                movne   pc, lr
                 mov     r2, #1
                 mov     r3, #0
                 mcr     p15, 0, ip, c7, c6, 0   @ invalidate D cache
@@ -1064,6 +1065,8 @@ __armv4_mpu_cache_flush:
                 mov     pc, lr
                 
 __fa526_cache_flush:
+                tst     r4, #1
+                movne   pc, lr
                 mov     r1, #0
                 mcr     p15, 0, r1, c7, c14, 0  @ clean and invalidate D cache
                 mcr     p15, 0, r1, c7, c5, 0   @ flush I cache
@@ -1072,13 +1075,16 @@ __fa526_cache_flush:
 
 __armv6_mmu_cache_flush:
                 mov     r1, #0
-                mcr     p15, 0, r1, c7, c14, 0  @ clean+invalidate D
+                tst     r4, #1
+                mcreq   p15, 0, r1, c7, c14, 0  @ clean+invalidate D
                 mcr     p15, 0, r1, c7, c5, 0   @ invalidate I+BTB
-                mcr     p15, 0, r1, c7, c15, 0  @ clean+invalidate unified
+                mcreq   p15, 0, r1, c7, c15, 0  @ clean+invalidate unified
                 mcr     p15, 0, r1, c7, c10, 4  @ drain WB
                 mov     pc, lr
 
 __armv7_mmu_cache_flush:
+                tst     r4, #1
+                bne     iflush
                 mrc     p15, 0, r10, c0, c1, 5  @ read ID_MMFR1
                 tst     r10, #0xf << 16         @ hierarchical cache (ARMv7)
                 mov     r10, #0
@@ -1139,6 +1145,8 @@ iflush:
                 mov     pc, lr
 
 __armv5tej_mmu_cache_flush:
+                tst     r4, #1
+                movne   pc, lr
 1:              mrc     p15, 0, r15, c7, c14, 3 @ test,clean,invalidate D cache
                 bne     1b
                 mcr     p15, 0, r0, c7, c5, 0   @ flush I cache
@@ -1146,6 +1154,8 @@ __armv5tej_mmu_cache_flush:
                 mov     pc, lr
 
 __armv4_mmu_cache_flush:
+                tst     r4, #1
+                movne   pc, lr
                 mov     r2, #64*1024            @ default: 32K dcache size (*2)
                 mov     r11, #32                @ default: 32 byte line size
                 mrc     p15, 0, r3, c0, c0, 1   @ read cache type
@@ -1179,6 +1189,8 @@ no_cache_id:
 
 __armv3_mmu_cache_flush:
 __armv3_mpu_cache_flush:
+                tst     r4, #1
+                movne   pc, lr
                 mov     r1, #0
                 mcr     p15, 0, r1, c7, c0, 0   @ invalidate whole cache v3
                 mov     pc, lr