From: Nikita Zhandarovich n.zhandarovich@fintech.ru
[ Upstream commit 1becc57cd1a905e2aa0e1eca60d2a37744525c4a ]
Function rv740_get_decoded_reference_divider() may return 0 due to unpredictable reference divider value calculated in radeon_atom_get_clock_dividers(). This will lead to division-by-zero error once that value is used as a divider in calculating 'clk_s'. While unlikely, this issue should nonetheless be prevented so add a sanity check for such cases by testing 'decoded_ref' value against 0.
Found by Linux Verification Center (linuxtesting.org) with static analysis tool SVACE.
v2: minor coding style fixes (Alex) In practice this should actually happen as the vbios should be properly populated.
Fixes: 66229b200598 ("drm/radeon/kms: add dpm support for rv7xx (v4)") Signed-off-by: Nikita Zhandarovich n.zhandarovich@fintech.ru Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/radeon/cypress_dpm.c | 8 ++++++-- drivers/gpu/drm/radeon/ni_dpm.c | 8 ++++++-- drivers/gpu/drm/radeon/rv740_dpm.c | 8 ++++++-- 3 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/radeon/cypress_dpm.c b/drivers/gpu/drm/radeon/cypress_dpm.c index 3eb7899a4035b..2c637e04dfebc 100644 --- a/drivers/gpu/drm/radeon/cypress_dpm.c +++ b/drivers/gpu/drm/radeon/cypress_dpm.c @@ -558,8 +558,12 @@ static int cypress_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = ss.percentage * (0x4000 * dividers.whole_fb_div + 0x800 * dividers.frac_fb_div) / (clk_s * 625);
mpll_ss1 &= ~CLKV_MASK; diff --git a/drivers/gpu/drm/radeon/ni_dpm.c b/drivers/gpu/drm/radeon/ni_dpm.c index a7273c01de34b..2a9d415400f79 100644 --- a/drivers/gpu/drm/radeon/ni_dpm.c +++ b/drivers/gpu/drm/radeon/ni_dpm.c @@ -2239,8 +2239,12 @@ static int ni_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = ss.percentage * (0x4000 * dividers.whole_fb_div + 0x800 * dividers.frac_fb_div) / (clk_s * 625);
mpll_ss1 &= ~CLKV_MASK; diff --git a/drivers/gpu/drm/radeon/rv740_dpm.c b/drivers/gpu/drm/radeon/rv740_dpm.c index afd597ec50858..50290e93c79dc 100644 --- a/drivers/gpu/drm/radeon/rv740_dpm.c +++ b/drivers/gpu/drm/radeon/rv740_dpm.c @@ -251,8 +251,12 @@ int rv740_populate_mclk_value(struct radeon_device *rdev, ASIC_INTERNAL_MEMORY_SS, vco_freq)) { u32 reference_clock = rdev->clock.mpll.reference_freq; u32 decoded_ref = rv740_get_decoded_reference_divider(dividers.ref_div); - u32 clk_s = reference_clock * 5 / (decoded_ref * ss.rate); - u32 clk_v = 0x40000 * ss.percentage * + u32 clk_s, clk_v; + + if (!decoded_ref) + return -EINVAL; + clk_s = reference_clock * 5 / (decoded_ref * ss.rate); + clk_v = 0x40000 * ss.percentage * (dividers.whole_fb_div + (dividers.frac_fb_div / 8)) / (clk_s * 10000);
mpll_ss1 &= ~CLKV_MASK;