4.14-stable review patch. If anyone has any objections, please let me know.
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From: Devi Priya quic_devipriy@quicinc.com
[ Upstream commit f7b7d30158cff246667273bd2a62fc93ee0725d2 ]
If the parent clock rate is greater than unsigned long max/2 then integer overflow happens when calculating the clock rate on 32-bit systems. As RCG2 uses half integer dividers, the clock rate is first being multiplied by 2 which will overflow the unsigned long max value. Hence, replace the common pattern of doing 64-bit multiplication and then a do_div() call with simpler mult_frac call.
Fixes: bcd61c0f535a ("clk: qcom: Add support for root clock generators (RCGs)") Signed-off-by: Devi Priya quic_devipriy@quicinc.com Reviewed-by: Marijn Suijten marijn.suijten@somainline.org Link: https://lore.kernel.org/r/20230901073640.4973-1-quic_devipriy@quicinc.com [bjorn: Also drop unnecessary {} around single statements] Signed-off-by: Bjorn Andersson andersson@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/qcom/clk-rcg2.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c index 9743af6ae84f9..7c7c140bba4c3 100644 --- a/drivers/clk/qcom/clk-rcg2.c +++ b/drivers/clk/qcom/clk-rcg2.c @@ -139,17 +139,11 @@ static int clk_rcg2_set_parent(struct clk_hw *hw, u8 index) static unsigned long calc_rate(unsigned long rate, u32 m, u32 n, u32 mode, u32 hid_div) { - if (hid_div) { - rate *= 2; - rate /= hid_div + 1; - } + if (hid_div) + rate = mult_frac(rate, 2, hid_div + 1);
- if (mode) { - u64 tmp = rate; - tmp *= m; - do_div(tmp, n); - rate = tmp; - } + if (mode) + rate = mult_frac(rate, m, n);
return rate; }