Hello Jaehoon, > -----Original Message----- > From: Jaehoon Chung [mailto:jh80.chung@xxxxxxxxxxx] > Sent: Monday, June 20, 2016 11:34 AM > To: Seung-Woo Kim; ulf.hansson@xxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2] mmc: dw_mmc: remove UBSAN warning in dw_mci_setup_bus() > > Hi SeungWoo, > > On 06/17/2016 02:16 PM, Seung-Woo Kim wrote: > > This patch removes following UBSAN warnings in dw_mci_setup_bus(). > > > > 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 warnings are caused because of shift with more than 31 on 32 > > bit variable, so this patch fixes to keep both clock and divider > > instead of shift. > > > > Signed-off-by: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx> > > --- > > drivers/mmc/host/dw_mmc.c | 8 +++++--- > > drivers/mmc/host/dw_mmc.h | 8 +++++--- > > 2 files changed, 10 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > > index 2cc6123..d05c8cc 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 (clock != slot->__clk_old || div != slot->__div_old || > > + force_clkinit) > > I have realized why we put this condition..after checking your below codes. > This was patch to avoid the spamming for CONFIG_MMC_CLKGATE.. > but CONFIG_MMC_CLKAGET didn't use anymore.. I think we can remove this condition. > > How about? There is no CONFIG_MMC_CLKAGET, but message is still printed. So without the condition check, there will be too much log. If you will just remove below print, then I agree about removing the condition and __clk_old, instead of my patch. Thanks, - Seung-Woo Kim > > Best Regards, > Jaehoon Chung > > > 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, > > @@ -1128,8 +1129,9 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) > > /* inform CIU */ > > mci_send_cmd(slot, sdmmc_cmd_bits, 0); > > > > - /* keep the clock with reflecting clock dividor */ > > - slot->__clk_old = clock << div; > > + /* keep the clock and clock divider */ > > + slot->__clk_old = clock; > > + slot->__div_old = div; > > } > > > > host->current_speed = clock; > > diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h > > index 1e8d838..fdfc3f5 100644 > > --- a/drivers/mmc/host/dw_mmc.h > > +++ b/drivers/mmc/host/dw_mmc.h > > @@ -245,9 +245,10 @@ extern int dw_mci_resume(struct dw_mci *host); > > * @queue_node: List node for placing this node in the @queue list of > > * &struct dw_mci. > > * @clock: Clock rate configured by set_ios(). Protected by host->lock. > > - * @__clk_old: The last updated clock with reflecting clock divider. > > - * Keeping track of this helps us to avoid spamming the console > > - * with CONFIG_MMC_CLKGATE. > > + * @__clk_old: The last updated clock. > > + * @__div_old: The last updated clock divider. > > + * Keeping track of clock and clock divider helps us to avoid spamming > > + * the console with CONFIG_MMC_CLKGATE. > > * @flags: Random state bits associated with the slot. > > * @id: Number of this slot. > > * @sdio_id: Number of this slot in the SDIO interrupt registers. > > @@ -263,6 +264,7 @@ struct dw_mci_slot { > > > > unsigned int clock; > > unsigned int __clk_old; > > + unsigned int __div_old; > > > > unsigned long flags; > > #define DW_MMC_CARD_PRESENT 0 > > -- 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
