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| author | Vincent Palatin <vpalatin@chromium.org> | 2015-01-22 11:53:10 -0800 |
|---|---|---|
| committer | ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> | 2015-01-23 00:28:45 +0000 |
| commit | da733f3aae80afa30f6d12a3032972eb08d06635 (patch) | |
| tree | 4117ef58b88de30b705d030c5fd47bbf59921b35 | |
| parent | f39dc502130ce1e5ae2b9589425c135781defba1 (diff) | |
| download | chrome-ec-da733f3aae80afa30f6d12a3032972eb08d06635.tar.gz | |
lm4: ignore overlapping LPC commands
If the AP ignores the LPC_ST_BUSY bit (which is software-defined) and
tries to send a second host command while the first one is still
processed, we discard it.
This doesn't prevent the host to re-write the command arguments stored
in LPC shared mem (aka LPC_POOL_CMD_DATA) but when we will call
host_packet_receive, we will have either the old arguments or the new
arguments (or even a mix of both, which is less unlikely to pass the
checksum check), and we will copy them once before calling the HOSTCMD
task. So the host command task will have a single coherent (not
changing) view of the arguments when performing its input validation.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
BRANCH=samus
BUG=chrome-os-partner:31492 chrome-os-partner:23806
TEST=Boot Samus and play with ectool
Change-Id: I9aa1b8cdac05e323b91998188bd873826e83c274
Reviewed-on: https://chromium-review.googlesource.com/242593
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Trybot-Ready: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
| -rw-r--r-- | chip/lm4/lpc.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/chip/lm4/lpc.c b/chip/lm4/lpc.c index 6bab4fb761..0f3e9b8b1c 100644 --- a/chip/lm4/lpc.c +++ b/chip/lm4/lpc.c @@ -473,8 +473,8 @@ static void handle_acpi_write(int is_cmd) */ static void handle_host_write(int is_cmd) { - /* Ignore data writes */ - if (!is_cmd) { + /* Ignore data writes or overlapping commands from host */ + if (!is_cmd || (LM4_LPC_ST(LPC_CH_CMD) & LM4_LPC_ST_BUSY)) { LM4_LPC_ST(LPC_CH_CMD) &= ~LM4_LPC_ST_FRMH; return; } |