| Message ID | 20200925171608.30881-1-manivannan.sadhasivam@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | bus: mhi: core: debugfs: Use correct format specifiers for addresses | expand |
On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > For exposing the addresses of read/write pointers and doorbell register, > let's use the correct format specifiers. This fixes the following issues > generated using W=1 build in ARM32 and reported by Kbuild bot: > > All warnings (new ones prefixed by >>): > >>> drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > mhi_event->db_cfg.db_val); > ^~~~~~~~~~~~~~~~~~~~~~~~ > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > mhi_chan->db_cfg.db_val); > ^~~~~~~~~~~~~~~~~~~~~~~ > 2 warnings generated. > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > ^ > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > (u64)ring->rp, (u64)ring->wp, > ^ > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > (u64)ring->rp, (u64)ring->wp, > ^ > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > ~~~^ > %x > drivers/bus/mhi/core/debugfs.c:123:7: > mhi_chan->db_cfg.db_val); > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > --- > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > branch. > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > index 53d05a8e168d..2536ff92b76f 100644 > --- a/drivers/bus/mhi/core/debugfs.c > +++ b/drivers/bus/mhi/core/debugfs.c > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > er_ctxt->wp); > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > - mhi_event->db_cfg.db_val); > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > + &mhi_event->db_cfg.db_val); > } > > return 0; > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > - (u64)ring->rp, (u64)ring->wp, > - mhi_chan->db_cfg.db_val); > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > + ring->rp, ring->wp, > + &mhi_chan->db_cfg.db_val); > } > > return 0; > Documentation/printk-formats.txt seems to point out that %px is "insecure" and thus perhaps not preferred. Are we assuming that debugfs is only accessible by root, and thus the %px usage here is effectively the same as %pK? -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote: > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > > For exposing the addresses of read/write pointers and doorbell register, > > let's use the correct format specifiers. This fixes the following issues > > generated using W=1 build in ARM32 and reported by Kbuild bot: > > > > All warnings (new ones prefixed by >>): > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > mhi_event->db_cfg.db_val); > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > mhi_chan->db_cfg.db_val); > > ^~~~~~~~~~~~~~~~~~~~~~~ > > 2 warnings generated. > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > > ^ > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > (u64)ring->rp, (u64)ring->wp, > > ^ > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > (u64)ring->rp, (u64)ring->wp, > > ^ > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > ~~~^ > > %x > > drivers/bus/mhi/core/debugfs.c:123:7: > > mhi_chan->db_cfg.db_val); > > > > Reported-by: kernel test robot <lkp@intel.com> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > > --- > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > > branch. > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > > index 53d05a8e168d..2536ff92b76f 100644 > > --- a/drivers/bus/mhi/core/debugfs.c > > +++ b/drivers/bus/mhi/core/debugfs.c > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > > er_ctxt->wp); > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > > - mhi_event->db_cfg.db_val); > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > > + &mhi_event->db_cfg.db_val); > > } > > return 0; > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > - (u64)ring->rp, (u64)ring->wp, > > - mhi_chan->db_cfg.db_val); > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > > + ring->rp, ring->wp, > > + &mhi_chan->db_cfg.db_val); > > } > > return 0; > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure" > and thus perhaps not preferred. Are we assuming that debugfs is only > accessible by root, and thus the %px usage here is effectively the same as > %pK? > No, this debugfs entry can be read by non-root users also. But the idea here is to effectively show the addresses to everyone so I don't think we need to hide it. The term "insecure" applies to kernel log where exposing the address doesn't make much sense (except for few obvious reasons). Thanks, Mani > -- > Jeffrey Hugo > Qualcomm Technologies, Inc. is a member of the > Code Aurora Forum, a Linux Foundation Collaborative Project.
On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote: > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote: > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > > > For exposing the addresses of read/write pointers and doorbell register, > > > let's use the correct format specifiers. This fixes the following issues > > > generated using W=1 build in ARM32 and reported by Kbuild bot: > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > mhi_event->db_cfg.db_val); > > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > mhi_chan->db_cfg.db_val); > > > ^~~~~~~~~~~~~~~~~~~~~~~ > > > 2 warnings generated. > > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > > > ^ > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > (u64)ring->rp, (u64)ring->wp, > > > ^ > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > (u64)ring->rp, (u64)ring->wp, > > > ^ > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > ~~~^ > > > %x > > > drivers/bus/mhi/core/debugfs.c:123:7: > > > mhi_chan->db_cfg.db_val); > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > > > --- > > > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > > > branch. > > > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > > > index 53d05a8e168d..2536ff92b76f 100644 > > > --- a/drivers/bus/mhi/core/debugfs.c > > > +++ b/drivers/bus/mhi/core/debugfs.c > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > > > er_ctxt->wp); > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > > > - mhi_event->db_cfg.db_val); > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > > > + &mhi_event->db_cfg.db_val); > > > } > > > return 0; > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > - (u64)ring->rp, (u64)ring->wp, > > > - mhi_chan->db_cfg.db_val); > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > > > + ring->rp, ring->wp, > > > + &mhi_chan->db_cfg.db_val); > > > } > > > return 0; > > > > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure" > > and thus perhaps not preferred. Are we assuming that debugfs is only > > accessible by root, and thus the %px usage here is effectively the same as > > %pK? > > > > No, this debugfs entry can be read by non-root users also. How, the mount point of debugfs is restricted to root only :) > But the idea here > is to effectively show the addresses to everyone so I don't think we need to > hide it. The term "insecure" applies to kernel log where exposing the address > doesn't make much sense (except for few obvious reasons). Why does normal users need to see a kernel address? What can they do with this? Why can't we use the "normal" hashed way of showing a kernel address instead? thanks, greg k-h
On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote: > On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote: > > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote: > > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > > > > For exposing the addresses of read/write pointers and doorbell register, > > > > let's use the correct format specifiers. This fixes the following issues > > > > generated using W=1 build in ARM32 and reported by Kbuild bot: > > > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > mhi_event->db_cfg.db_val); > > > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > mhi_chan->db_cfg.db_val); > > > > ^~~~~~~~~~~~~~~~~~~~~~~ > > > > 2 warnings generated. > > > > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > > > > ^ > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > (u64)ring->rp, (u64)ring->wp, > > > > ^ > > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > (u64)ring->rp, (u64)ring->wp, > > > > ^ > > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > ~~~^ > > > > %x > > > > drivers/bus/mhi/core/debugfs.c:123:7: > > > > mhi_chan->db_cfg.db_val); > > > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > > > > --- > > > > > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > > > > branch. > > > > > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > > > > index 53d05a8e168d..2536ff92b76f 100644 > > > > --- a/drivers/bus/mhi/core/debugfs.c > > > > +++ b/drivers/bus/mhi/core/debugfs.c > > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > > > > er_ctxt->wp); > > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > > > > - mhi_event->db_cfg.db_val); > > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > > > > + &mhi_event->db_cfg.db_val); > > > > } > > > > return 0; > > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > - (u64)ring->rp, (u64)ring->wp, > > > > - mhi_chan->db_cfg.db_val); > > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > > > > + ring->rp, ring->wp, > > > > + &mhi_chan->db_cfg.db_val); > > > > } > > > > return 0; > > > > > > > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure" > > > and thus perhaps not preferred. Are we assuming that debugfs is only > > > accessible by root, and thus the %px usage here is effectively the same as > > > %pK? > > > > > > > No, this debugfs entry can be read by non-root users also. > > How, the mount point of debugfs is restricted to root only :) > Sigh... I just went with the file permission of 444 :/ > > But the idea here > > is to effectively show the addresses to everyone so I don't think we need to > > hide it. The term "insecure" applies to kernel log where exposing the address > > doesn't make much sense (except for few obvious reasons). > > Why does normal users need to see a kernel address? What can they do > with this? Why can't we use the "normal" hashed way of showing a kernel > address instead? > It was the original implementation and as you brushed my memory, only root can mount and read the content, so why we should hide? Thanks, Mani > thanks, > > greg k-h
On Sat, Sep 26, 2020 at 12:46:04PM +0530, Manivannan Sadhasivam wrote: > On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote: > > On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote: > > > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote: > > > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > > > > > For exposing the addresses of read/write pointers and doorbell register, > > > > > let's use the correct format specifiers. This fixes the following issues > > > > > generated using W=1 build in ARM32 and reported by Kbuild bot: > > > > > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > > mhi_event->db_cfg.db_val); > > > > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > > mhi_chan->db_cfg.db_val); > > > > > ^~~~~~~~~~~~~~~~~~~~~~~ > > > > > 2 warnings generated. > > > > > > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > > > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > > > > > ^ > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > > > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > (u64)ring->rp, (u64)ring->wp, > > > > > ^ > > > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > (u64)ring->rp, (u64)ring->wp, > > > > > ^ > > > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > > > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > > ~~~^ > > > > > %x > > > > > drivers/bus/mhi/core/debugfs.c:123:7: > > > > > mhi_chan->db_cfg.db_val); > > > > > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > > > > > --- > > > > > > > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > > > > > branch. > > > > > > > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > > > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > > > > > index 53d05a8e168d..2536ff92b76f 100644 > > > > > --- a/drivers/bus/mhi/core/debugfs.c > > > > > +++ b/drivers/bus/mhi/core/debugfs.c > > > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > > > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > > > > > er_ctxt->wp); > > > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > > > > > - mhi_event->db_cfg.db_val); > > > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > > > > > + &mhi_event->db_cfg.db_val); > > > > > } > > > > > return 0; > > > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > > > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > > > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > > - (u64)ring->rp, (u64)ring->wp, > > > > > - mhi_chan->db_cfg.db_val); > > > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > > > > > + ring->rp, ring->wp, > > > > > + &mhi_chan->db_cfg.db_val); > > > > > } > > > > > return 0; > > > > > > > > > > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure" > > > > and thus perhaps not preferred. Are we assuming that debugfs is only > > > > accessible by root, and thus the %px usage here is effectively the same as > > > > %pK? > > > > > > > > > > No, this debugfs entry can be read by non-root users also. > > > > How, the mount point of debugfs is restricted to root only :) > > > > Sigh... I just went with the file permission of 444 :/ > > > > But the idea here > > > is to effectively show the addresses to everyone so I don't think we need to > > > hide it. The term "insecure" applies to kernel log where exposing the address > > > doesn't make much sense (except for few obvious reasons). > > > > Why does normal users need to see a kernel address? What can they do > > with this? Why can't we use the "normal" hashed way of showing a kernel > > address instead? > > > > It was the original implementation and as you brushed my memory, only root can > mount and read the content, so why we should hide? Why shouldn't you? It's good to have defense in depth, userspace should not care about a real kernel pointer value, right? THat's why we have the hashed number instead, please use that. thanks, greg k-h
On Sat, Sep 26, 2020 at 02:46:26PM +0200, Greg KH wrote: > On Sat, Sep 26, 2020 at 12:46:04PM +0530, Manivannan Sadhasivam wrote: > > On Sat, Sep 26, 2020 at 07:39:14AM +0200, Greg KH wrote: > > > On Sat, Sep 26, 2020 at 10:57:42AM +0530, Manivannan Sadhasivam wrote: > > > > On Fri, Sep 25, 2020 at 12:01:54PM -0600, Jeffrey Hugo wrote: > > > > > On 9/25/2020 11:16 AM, Manivannan Sadhasivam wrote: > > > > > > For exposing the addresses of read/write pointers and doorbell register, > > > > > > let's use the correct format specifiers. This fixes the following issues > > > > > > generated using W=1 build in ARM32 and reported by Kbuild bot: > > > > > > > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > > > > > > > drivers/bus/mhi/core/debugfs.c:75:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > > > mhi_event->db_cfg.db_val); > > > > > > ^~~~~~~~~~~~~~~~~~~~~~~~ > > > > > > drivers/bus/mhi/core/debugfs.c:123:7: warning: format specifies type 'unsigned long long' but the argument has type 'dma_addr_t' (aka 'unsigned int') [-Wformat] > > > > > > mhi_chan->db_cfg.db_val); > > > > > > ^~~~~~~~~~~~~~~~~~~~~~~ > > > > > > 2 warnings generated. > > > > > > > > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_events_show’: > > > > > > drivers/bus/mhi/core/debugfs.c:74:51: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > > seq_printf(m, " local rp: 0x%llx db: 0x%pad\n", (u64)ring->rp, > > > > > > ^ > > > > > > drivers/bus/mhi/core/debugfs.c: In function ‘mhi_debugfs_channels_show’: > > > > > > drivers/bus/mhi/core/debugfs.c:122:7: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > > (u64)ring->rp, (u64)ring->wp, > > > > > > ^ > > > > > > drivers/bus/mhi/core/debugfs.c:122:22: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] > > > > > > (u64)ring->rp, (u64)ring->wp, > > > > > > ^ > > > > > > drivers/bus/mhi/core/debugfs.c:121:62: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘dma_addr_t {aka unsigned int}’ [-Wformat=] > > > > > > seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > > > ~~~^ > > > > > > %x > > > > > > drivers/bus/mhi/core/debugfs.c:123:7: > > > > > > mhi_chan->db_cfg.db_val); > > > > > > > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > > > > > > --- > > > > > > > > > > > > Greg: This fixes the issue seen while testing the char-misc/char-misc-testing > > > > > > branch. > > > > > > > > > > > > drivers/bus/mhi/core/debugfs.c | 10 +++++----- > > > > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > > > > > > > diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c > > > > > > index 53d05a8e168d..2536ff92b76f 100644 > > > > > > --- a/drivers/bus/mhi/core/debugfs.c > > > > > > +++ b/drivers/bus/mhi/core/debugfs.c > > > > > > @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) > > > > > > seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, > > > > > > er_ctxt->wp); > > > > > > - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, > > > > > > - mhi_event->db_cfg.db_val); > > > > > > + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, > > > > > > + &mhi_event->db_cfg.db_val); > > > > > > } > > > > > > return 0; > > > > > > @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) > > > > > > seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", > > > > > > chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); > > > > > > - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", > > > > > > - (u64)ring->rp, (u64)ring->wp, > > > > > > - mhi_chan->db_cfg.db_val); > > > > > > + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", > > > > > > + ring->rp, ring->wp, > > > > > > + &mhi_chan->db_cfg.db_val); > > > > > > } > > > > > > return 0; > > > > > > > > > > > > > > > > Documentation/printk-formats.txt seems to point out that %px is "insecure" > > > > > and thus perhaps not preferred. Are we assuming that debugfs is only > > > > > accessible by root, and thus the %px usage here is effectively the same as > > > > > %pK? > > > > > > > > > > > > > No, this debugfs entry can be read by non-root users also. > > > > > > How, the mount point of debugfs is restricted to root only :) > > > > > > > Sigh... I just went with the file permission of 444 :/ > > > > > > But the idea here > > > > is to effectively show the addresses to everyone so I don't think we need to > > > > hide it. The term "insecure" applies to kernel log where exposing the address > > > > doesn't make much sense (except for few obvious reasons). > > > > > > Why does normal users need to see a kernel address? What can they do > > > with this? Why can't we use the "normal" hashed way of showing a kernel > > > address instead? > > > > > > > It was the original implementation and as you brushed my memory, only root can > > mount and read the content, so why we should hide? > > Why shouldn't you? It's good to have defense in depth, userspace should > not care about a real kernel pointer value, right? THat's why we have > the hashed number instead, please use that. > Okay. Will do it in next revision. Thanks, Mani > thanks, > > greg k-h
diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c index 53d05a8e168d..2536ff92b76f 100644 --- a/drivers/bus/mhi/core/debugfs.c +++ b/drivers/bus/mhi/core/debugfs.c @@ -71,8 +71,8 @@ static int mhi_debugfs_events_show(struct seq_file *m, void *d) seq_printf(m, " rp: 0x%llx wp: 0x%llx", er_ctxt->rp, er_ctxt->wp); - seq_printf(m, " local rp: 0x%llx db: 0x%llx\n", (u64)ring->rp, - mhi_event->db_cfg.db_val); + seq_printf(m, " local rp: 0x%px db: 0x%pad\n", ring->rp, + &mhi_event->db_cfg.db_val); } return 0; @@ -118,9 +118,9 @@ static int mhi_debugfs_channels_show(struct seq_file *m, void *d) seq_printf(m, " base: 0x%llx len: 0x%llx wp: 0x%llx", chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp); - seq_printf(m, " local rp: 0x%llx local wp: 0x%llx db: 0x%llx\n", - (u64)ring->rp, (u64)ring->wp, - mhi_chan->db_cfg.db_val); + seq_printf(m, " local rp: 0x%px local wp: 0x%px db: 0x%pad\n", + ring->rp, ring->wp, + &mhi_chan->db_cfg.db_val); } return 0;