diff options
authorVikram Mulukutla <markivx@codeaurora.org>2014-08-04 18:31:45 -0700
committerAndrey Konovalov <andrey.konovalov@linaro.org>2015-01-13 17:56:49 +0300
commit01d413cf5710e009f6a89c0915fafd63282ab4f2 (patch)
parent84384e62b42bd7371460963a3e6455622d30f4e3 (diff)
ARM: qcom: scm: Flush the command buffer only instead of the entire cache
scm_call flushes the entire cache before calling into the secure world. This is both a performance penalty as well as insufficient on SMP systems where the CPUs possess a write-back L1 cache. Flush only the command and response buffers instead, moving the responsibility of flushing any other cached buffer (being passed to the secure world) to callers. Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Kumar Gala <galak@codeaurora.org>
1 files changed, 12 insertions, 5 deletions
diff --git a/arch/arm/mach-qcom/scm.c b/arch/arm/mach-qcom/scm.c
index c08786ebf116..ec37b037e69c 100644
--- a/arch/arm/mach-qcom/scm.c
+++ b/arch/arm/mach-qcom/scm.c
@@ -196,12 +196,12 @@ static int __scm_call(const struct scm_command *cmd)
u32 cmd_addr = virt_to_phys(cmd);
- * Flush the entire cache here so callers don't have to remember
- * to flush the cache when passing physical addresses to the secure
- * side in the buffer.
+ * Flush the command buffer so that the secure world sees
+ * the correct data.
- flush_cache_all();
- outer_flush_all();
+ __cpuc_flush_dcache_area((void *)cmd, cmd->len);
+ outer_flush_range(cmd_addr, cmd_addr + cmd->len);
ret = smc(cmd_addr);
if (ret < 0)
ret = scm_remap_error(ret);
@@ -238,6 +238,13 @@ static void scm_inv_range(unsigned long start, unsigned long end)
* @resp_len: length of the response buffer
* Sends a command to the SCM and waits for the command to finish processing.
+ *
+ * A note on cache maintenance:
+ * Note that any buffers that are expected to be accessed by the secure world
+ * must be flushed before invoking scm_call and invalidated in the cache
+ * immediately after scm_call returns. Cache maintenance on the command and
+ * response buffers is taken care of by scm_call; however, callers are
+ * responsible for any other cached buffers passed over to the secure world.
int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
void *resp_buf, size_t resp_len)