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Subject[PATCH 4.14 23/89] spi: spi-dw: Add lock protect dw_spi rx/tx to prevent concurrent calls
Date
From: wuxu.wu <wuxu.wu@huawei.com>

[ Upstream commit 19b61392c5a852b4e8a0bf35aecb969983c5932d ]

dw_spi_irq() and dw_spi_transfer_one concurrent calls.

I find a panic in dw_writer(): txw = *(u8 *)(dws->tx), when dw->tx==null,
dw->len==4, and dw->tx_end==1.

When tpm driver's message overtime dw_spi_irq() and dw_spi_transfer_one
may concurrent visit dw_spi, so I think dw_spi structure lack of protection.

Otherwise dw_spi_transfer_one set dw rx/tx buffer and then open irq,
store dw rx/tx instructions and other cores handle irq load dw rx/tx
instructions may out of order.

[ 1025.321302] Call trace:
...
[ 1025.321319] __crash_kexec+0x98/0x148
[ 1025.321323] panic+0x17c/0x314
[ 1025.321329] die+0x29c/0x2e8
[ 1025.321334] die_kernel_fault+0x68/0x78
[ 1025.321337] __do_kernel_fault+0x90/0xb0
[ 1025.321346] do_page_fault+0x88/0x500
[ 1025.321347] do_translation_fault+0xa8/0xb8
[ 1025.321349] do_mem_abort+0x68/0x118
[ 1025.321351] el1_da+0x20/0x8c
[ 1025.321362] dw_writer+0xc8/0xd0
[ 1025.321364] interrupt_transfer+0x60/0x110
[ 1025.321365] dw_spi_irq+0x48/0x70
...

Signed-off-by: wuxu.wu <wuxu.wu@huawei.com>
Link: https://lore.kernel.org/r/1577849981-31489-1-git-send-email-wuxu.wu@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-dw.c | 15 ++++++++++++---
drivers/spi/spi-dw.h | 1 +
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index b217c22ff72fe..b461200871f89 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -180,9 +180,11 @@ static inline u32 rx_max(struct dw_spi *dws)

static void dw_writer(struct dw_spi *dws)
{
- u32 max = tx_max(dws);
+ u32 max;
u16 txw = 0;

+ spin_lock(&dws->buf_lock);
+ max = tx_max(dws);
while (max--) {
/* Set the tx word if the transfer's original "tx" is not null */
if (dws->tx_end - dws->len) {
@@ -194,13 +196,16 @@ static void dw_writer(struct dw_spi *dws)
dw_write_io_reg(dws, DW_SPI_DR, txw);
dws->tx += dws->n_bytes;
}
+ spin_unlock(&dws->buf_lock);
}

static void dw_reader(struct dw_spi *dws)
{
- u32 max = rx_max(dws);
+ u32 max;
u16 rxw;

+ spin_lock(&dws->buf_lock);
+ max = rx_max(dws);
while (max--) {
rxw = dw_read_io_reg(dws, DW_SPI_DR);
/* Care rx only if the transfer's original "rx" is not null */
@@ -212,6 +217,7 @@ static void dw_reader(struct dw_spi *dws)
}
dws->rx += dws->n_bytes;
}
+ spin_unlock(&dws->buf_lock);
}

static void int_error_stop(struct dw_spi *dws, const char *msg)
@@ -284,18 +290,20 @@ static int dw_spi_transfer_one(struct spi_master *master,
{
struct dw_spi *dws = spi_master_get_devdata(master);
struct chip_data *chip = spi_get_ctldata(spi);
+ unsigned long flags;
u8 imask = 0;
u16 txlevel = 0;
u32 cr0;
int ret;

dws->dma_mapped = 0;
-
+ spin_lock_irqsave(&dws->buf_lock, flags);
dws->tx = (void *)transfer->tx_buf;
dws->tx_end = dws->tx + transfer->len;
dws->rx = transfer->rx_buf;
dws->rx_end = dws->rx + transfer->len;
dws->len = transfer->len;
+ spin_unlock_irqrestore(&dws->buf_lock, flags);

spi_enable_chip(dws, 0);

@@ -486,6 +494,7 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
dws->type = SSI_MOTO_SPI;
dws->dma_inited = 0;
dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
+ spin_lock_init(&dws->buf_lock);

ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
master);
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 5c07cf8f19e00..45fbf3ad591cc 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -117,6 +117,7 @@ struct dw_spi {
size_t len;
void *tx;
void *tx_end;
+ spinlock_t buf_lock;
void *rx;
void *rx_end;
int dma_mapped;
--
2.20.1


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