4.18-stable review patch. If anyone has any objections, please let me know.
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From: Sudeep Holla sudeep.holla@arm.com
[ Upstream commit 96d529bac562574600eda85726fcfa3eef6dde8e ]
Firmware can provide zero as values for sustained performance level and corresponding sustained frequency in kHz in order to hide the actual frequencies and provide only abstract values. It may endup with divide by zero scenario resulting in kernel panic.
Let's set the multiplication factor to one if either one or both of them (sustained_perf_level and sustained_freq) are set to zero.
Fixes: a9e3fbfaa0ff ("firmware: arm_scmi: add initial support for performance protocol") Reported-by: Ionela Voinescu ionela.voinescu@arm.com Signed-off-by: Sudeep Holla sudeep.holla@arm.com Signed-off-by: Olof Johansson olof@lixom.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/firmware/arm_scmi/perf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/firmware/arm_scmi/perf.c +++ b/drivers/firmware/arm_scmi/perf.c @@ -166,7 +166,13 @@ scmi_perf_domain_attributes_get(const st le32_to_cpu(attr->sustained_freq_khz); dom_info->sustained_perf_level = le32_to_cpu(attr->sustained_perf_level); - dom_info->mult_factor = (dom_info->sustained_freq_khz * 1000) / + if (!dom_info->sustained_freq_khz || + !dom_info->sustained_perf_level) + /* CPUFreq converts to kHz, hence default 1000 */ + dom_info->mult_factor = 1000; + else + dom_info->mult_factor = + (dom_info->sustained_freq_khz * 1000) / dom_info->sustained_perf_level; memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE); }