[PATCH v3] mmc: dw_mmc: remove UBSAN warning in dw_mci_setup_bus()

Seung-Woo Kim
2016-06-20T04:09:47Z

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 bit shift which is used to
filter spamming message for CONFIG_MMC_CLKGATE, but the config is
already removed. So this patch just removes the shift.

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
---
drivers/mmc/host/dw_mmc.c | 14 +++++---------
drivers/mmc/host/dw_mmc.h | 4 ----
2 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 2cc6123..bada11e 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1099,12 +1099,11 @@ 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)
- 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,
- div ? ((host->bus_hz / div) >> 1) :
- host->bus_hz, div);
+ 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,
+ div ? ((host->bus_hz / div) >> 1) :
+ host->bus_hz, div);

/* disable clock */
mci_writel(host, CLKENA, 0);
@@ -1127,9 +1126,6 @@ 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;
}

host->current_speed = clock;
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 1e8d838..5961037 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -245,9 +245,6 @@ 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.
* @flags: Random state bits associated with the slot.
* @id: Number of this slot.
* @sdio_id: Number of this slot in the SDIO interrupt registers.
@@ -262,7 +259,6 @@ struct dw_mci_slot {
struct list_head queue_node;

unsigned int clock;
- unsigned int __clk_old;

unsigned long flags;
#define DW_MMC_CARD_PRESENT 0
--
1.7.9.5