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| author | Vikram Mulukutla <markivx@codeaurora.org> | 2014-08-04 18:31:45 -0700 |
|---|---|---|
| committer | Kumar Gala <galak@codeaurora.org> | 2015-01-19 11:53:32 -0600 |
| commit | 404b5a97f5a2a718bb0feccc3712b1ab88f073d5 (patch) | |
| tree | 71750e563e24cef9437e2095d1cbaaf36c4c37a7 | |
| parent | 30cbb0c01bc98a2372966b8c5ac0ce1421cd933c (diff) | |
| download | linux-404b5a97f5a2a718bb0feccc3712b1ab88f073d5.tar.bz2 | |
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>
| -rw-r--r-- | arch/arm/mach-qcom/scm.c | 17 |
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) |