Hi Jaehoon, On 2016년 06월 09일 21:38, Jaehoon Chung wrote: > Hi Seung-Woo, > > On 06/08/2016 01:07 PM, Seung-Woo Kim wrote: >> This patch removes following UBSAN warnings in dw_mci_setup_bus(). >> The warnings are caused because of shift with more than 31 on 32 >> bit variable, so this patch fixes to shift only for less than 32. >> >> UBSAN: Undefined behaviour in drivers/mmc/host/dw_mmc.c:1102:14 >> shift exponent 250 is too large for 32-bit type 'unsigned int' >> Call trace: >> [<ffffff90080908a8>] dump_backtrace+0x0/0x380 >> [<ffffff9008090c3c>] show_stack+0x14/0x20 >> [<ffffff90087457b8>] dump_stack+0xe0/0x120 >> [<ffffff90087b1360>] ubsan_epilogue+0x18/0x68 >> [<ffffff90087b1a94>] __ubsan_handle_shift_out_of_bounds+0x18c/0x1bc >> [<ffffff9008d89cb8>] dw_mci_setup_bus+0x3a0/0x438 >> [...] >> >> UBSAN: Undefined behaviour in drivers/mmc/host/dw_mmc.c:1132:27 >> shift exponent 250 is too large for 32-bit type 'unsigned int' >> Call trace: >> [<ffffff90080908a8>] dump_backtrace+0x0/0x380 >> [<ffffff9008090c3c>] show_stack+0x14/0x20 >> [<ffffff90087457b8>] dump_stack+0xe0/0x120 >> [<ffffff90087b1360>] ubsan_epilogue+0x18/0x68 >> [<ffffff90087b1a94>] __ubsan_handle_shift_out_of_bounds+0x18c/0x1bc >> [<ffffff9008d89c9c>] dw_mci_setup_bus+0x384/0x438 > > The below message can be discarded.
You are right, like above message, below part can be replaced as [...]. > >> [<ffffff9008d89ed4>] dw_mci_set_ios+0x184/0x798 >> [<ffffff9008d550ac>] mmc_power_up+0x11c/0x260 >> [<ffffff9008d56b78>] mmc_start_host+0x88/0x100 >> [<ffffff9008d583f4>] mmc_add_host+0x6c/0x128 >> [<ffffff9008d88f90>] dw_mci_probe+0x1088/0x1750 >> [<ffffff9008d8caa8>] dw_mci_pltfm_register+0x108/0x178 >> [<ffffff9008d8dae4>] dw_mci_exynos_probe+0x4c/0x88 >> [<ffffff9008a03838>] platform_drv_probe+0x78/0x180 >> [<ffffff90089fe9fc>] driver_probe_device+0x144/0x460 >> [<ffffff90089fee0c>] __driver_attach+0xf4/0x140 >> [<ffffff90089fad98>] bus_for_each_dev+0xf0/0x160 >> [<ffffff90089fdc9c>] driver_attach+0x34/0x58 >> [<ffffff90089fd3e0>] bus_add_driver+0x2c0/0x398 >> [<ffffff9008a00924>] driver_register+0xbc/0x1e0 >> [<ffffff9008a02a94>] __platform_driver_register+0x84/0xa8 >> [<ffffff9009dd5730>] dw_mci_exynos_pltfm_driver_init+0x18/0x20 >> [<ffffff9008082df8>] do_one_initcall+0xa0/0x2c8 >> [<ffffff9009d81780>] kernel_init_freeable+0x52c/0x5dc >> [<ffffff9009519844>] kernel_init+0x1c/0xf8 >> [<ffffff9008086e10>] ret_from_fork+0x10/0x40 >> >> Signed-off-by: Seung-Woo Kim <sw0312....@samsung.com> >> --- >> drivers/mmc/host/dw_mmc.c | 5 +++-- >> 1 files changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 2cc6123..dff045e 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -1099,7 +1099,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, >> bool force_clkinit) >> >> div = (host->bus_hz != clock) ? DIV_ROUND_UP(div, 2) : 0; >> >> - if ((clock << div) != slot->__clk_old || force_clkinit) >> + if (((div < 32) ? (clock << div) : 0) != slot->__clk_old || > > Well, we don't expect that clock is 0. > if clock is 0, it should be passed to " if (!clock)".. > > During initializing card, clock is 400KHz or less..I understood what you want > to fix. > But I taught this is not correct. It seems slot->__clk_old is not really clock but a kind of value to store both clock and div in one variable. And at least, my compiler calculates right shift with more than 32 as 0. I am not sure there is other proper value for the case. By the way, in my test environment, clock is calculated as like following steps: mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 400000Hz, actual 400000HZ div = 250) mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 200000000Hz, actual 200000000HZ div = 0) mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 52000000Hz, actual 50000000HZ div = 2) mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 52000000Hz, actual 50000000HZ div = 4) mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 200000000Hz, actual 200000000HZ div = 1) and only the first case is reported as the warning. If you let me know any proper value, then I will fix with the value. Thanks, - Seung-Woo Kim > > >> + force_clkinit) >> dev_info(&slot->mmc->class_dev, >> "Bus speed (slot %d) = %dHz (slot req %dHz, >> actual %dHZ div = %d)\n", >> slot->id, host->bus_hz, clock, >> @@ -1129,7 +1130,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, >> bool force_clkinit) >> mci_send_cmd(slot, sdmmc_cmd_bits, 0); >> >> /* keep the clock with reflecting clock dividor */ >> - slot->__clk_old = clock << div; >> + slot->__clk_old = (div < 32) ? (clock << div) : 0; > > Also, clock is not 0.. > > > Best Regards, > Jaehoon Chung > >> } >> >> host->current_speed = clock; >> > > > -- Seung-Woo Kim Samsung Software R&D Center --
