Hi Seung-Woo, On 06/10/2016 10:29 AM, Seung-Woo Kim wrote: > 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.kim@xxxxxxxxxxx> >>> --- >>> 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. I think that "clock << div" and__old_clock are used for checking whether clock is changed. So it doesn't need to rotate with div. Could you check the below codes? if ((clock != slot->clk_old) || force_clkinit) ... slot->__clk_old = clock; Best Regards, Jaehoon Chung > > 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; >>> >> >> >> > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
