Re: [PATCH v4 8/8] bus: mhi: core: Ensure non-zero session or sequence ID values are used
On 2020-05-04 07:33, Jeffrey Hugo wrote: On 5/1/2020 8:32 PM, Bhaumik Bhatt wrote: While writing any sequence or session identifiers, it is possible that the host could write a zero value, whereas only non-zero values should be supported writes to those registers. Ensure that the host does not write a non-zero value for them and also log them in debug messages. Suggested-by: Jeffrey Hugo Signed-off-by: Bhaumik Bhatt --- drivers/bus/mhi/core/boot.c | 15 +++ drivers/bus/mhi/core/internal.h | 1 + 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c index e5fcde1..9fe9c59 100644 --- a/drivers/bus/mhi/core/boot.c +++ b/drivers/bus/mhi/core/boot.c @@ -43,10 +43,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl, lower_32_bits(mhi_buf->dma_addr)); mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS, mhi_buf->len); - sequence_id = prandom_u32() & BHIE_RXVECSTATUS_SEQNUM_BMSK; - - if (unlikely(!sequence_id)) - sequence_id = 1; + sequence_id = (MHI_RANDOM_U32_NONZERO & BHIE_RXVECSTATUS_SEQNUM_BMSK); I don't think this math works. For example, if MHI_RANDOM_U32_NONZERO is 0x0FF0, and BHIE_RXVECSTATUS_SEQNUM_BMSK is 0xF, then sequence_id will end up being 0. In this case, SEQNUM BMSK is set to 0x3FFF so this change will still work as we only supplied a non-zero number macro to AND with the mask. However, I agree that may not be the case always that we would know the bitmask in advance so it is better to fix it for good. Thanks for the catch! I have updated the change to have the macro take the bitmask as a parameter and output a non-zero value.
Re: [PATCH v4 8/8] bus: mhi: core: Ensure non-zero session or sequence ID values are used
On 5/1/2020 8:32 PM, Bhaumik Bhatt wrote: While writing any sequence or session identifiers, it is possible that the host could write a zero value, whereas only non-zero values should be supported writes to those registers. Ensure that the host does not write a non-zero value for them and also log them in debug messages. Suggested-by: Jeffrey Hugo Signed-off-by: Bhaumik Bhatt --- drivers/bus/mhi/core/boot.c | 15 +++ drivers/bus/mhi/core/internal.h | 1 + 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c index e5fcde1..9fe9c59 100644 --- a/drivers/bus/mhi/core/boot.c +++ b/drivers/bus/mhi/core/boot.c @@ -43,10 +43,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl, lower_32_bits(mhi_buf->dma_addr)); mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS, mhi_buf->len); - sequence_id = prandom_u32() & BHIE_RXVECSTATUS_SEQNUM_BMSK; - - if (unlikely(!sequence_id)) - sequence_id = 1; + sequence_id = (MHI_RANDOM_U32_NONZERO & BHIE_RXVECSTATUS_SEQNUM_BMSK); I don't think this math works. For example, if MHI_RANDOM_U32_NONZERO is 0x0FF0, and BHIE_RXVECSTATUS_SEQNUM_BMSK is 0xF, then sequence_id will end up being 0. -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
[PATCH v4 8/8] bus: mhi: core: Ensure non-zero session or sequence ID values are used
While writing any sequence or session identifiers, it is possible that
the host could write a zero value, whereas only non-zero values should
be supported writes to those registers. Ensure that the host does not
write a non-zero value for them and also log them in debug messages.
Suggested-by: Jeffrey Hugo
Signed-off-by: Bhaumik Bhatt
---
drivers/bus/mhi/core/boot.c | 15 +++
drivers/bus/mhi/core/internal.h | 1 +
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
index e5fcde1..9fe9c59 100644
--- a/drivers/bus/mhi/core/boot.c
+++ b/drivers/bus/mhi/core/boot.c
@@ -43,10 +43,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
lower_32_bits(mhi_buf->dma_addr));
mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS, mhi_buf->len);
- sequence_id = prandom_u32() & BHIE_RXVECSTATUS_SEQNUM_BMSK;
-
- if (unlikely(!sequence_id))
- sequence_id = 1;
+ sequence_id = (MHI_RANDOM_U32_NONZERO & BHIE_RXVECSTATUS_SEQNUM_BMSK);
mhi_write_reg_field(mhi_cntrl, base, BHIE_RXVECDB_OFFS,
BHIE_RXVECDB_SEQNUM_BMSK, BHIE_RXVECDB_SEQNUM_SHFT,
@@ -189,7 +186,9 @@ static int mhi_fw_load_amss(struct mhi_controller
*mhi_cntrl,
return -EIO;
}
- dev_dbg(dev, "Starting AMSS download via BHIe\n");
+ sequence_id = (MHI_RANDOM_U32_NONZERO & BHIE_TXVECSTATUS_SEQNUM_BMSK);
+ dev_dbg(dev, "Starting AMSS download via BHIe. Sequence ID:%u\n",
+ sequence_id);
mhi_write_reg(mhi_cntrl, base, BHIE_TXVECADDR_HIGH_OFFS,
upper_32_bits(mhi_buf->dma_addr));
@@ -198,7 +197,6 @@ static int mhi_fw_load_amss(struct mhi_controller
*mhi_cntrl,
mhi_write_reg(mhi_cntrl, base, BHIE_TXVECSIZE_OFFS, mhi_buf->len);
- sequence_id = prandom_u32() & BHIE_TXVECSTATUS_SEQNUM_BMSK;
mhi_write_reg_field(mhi_cntrl, base, BHIE_TXVECDB_OFFS,
BHIE_TXVECDB_SEQNUM_BMSK, BHIE_TXVECDB_SEQNUM_SHFT,
sequence_id);
@@ -246,14 +244,15 @@ static int mhi_fw_load_sbl(struct mhi_controller
*mhi_cntrl,
goto invalid_pm_state;
}
- dev_dbg(dev, "Starting SBL download via BHI\n");
+ session_id = (MHI_RANDOM_U32_NONZERO & BHI_TXDB_SEQNUM_BMSK);
+ dev_dbg(dev, "Starting SBL download via BHI. Session ID:%u\n",
+ session_id);
mhi_write_reg(mhi_cntrl, base, BHI_STATUS, 0);
mhi_write_reg(mhi_cntrl, base, BHI_IMGADDR_HIGH,
upper_32_bits(dma_addr));
mhi_write_reg(mhi_cntrl, base, BHI_IMGADDR_LOW,
lower_32_bits(dma_addr));
mhi_write_reg(mhi_cntrl, base, BHI_IMGSIZE, size);
- session_id = prandom_u32() & BHI_TXDB_SEQNUM_BMSK;
mhi_write_reg(mhi_cntrl, base, BHI_IMGTXDB, session_id);
read_unlock_bh(pm_lock);
diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 0965ca3..e4e6ea2 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -452,6 +452,7 @@ enum mhi_pm_state {
#define PRIMARY_CMD_RING 0
#define MHI_DEV_WAKE_DB127
#define MHI_MAX_MTU0x
+#define MHI_RANDOM_U32_NONZERO (prandom_u32_max(U32_MAX - 1) + 1)
enum mhi_er_type {
MHI_ER_TYPE_INVALID = 0x0,
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
