From: Vikram Mulukutla Date: Tue, 5 Aug 2014 01:31:45 +0000 (-0700) Subject: ARM: qcom: scm: Flush the command buffer only instead of the entire cache X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=404b5a97f5a2a718bb0feccc3712b1ab88f073d5;p=linux-beck.git 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 Signed-off-by: Stephen Boyd Signed-off-by: Kumar Gala --- 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)