| Message ID | 20200124132957.15769-2-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Fix debugfs register access while suspended | expand |
On Fri, Jan 24, 2020 at 2:30 PM Geert Uytterhoeven <geert+renesas@glider.be> wrote: > > Hardware registers of devices under control of power management cannot > be accessed at all times. If such a device is suspended, register > accesses may lead to undefined behavior, like reading bogus values, or > causing exceptions or system locks. > > Extend struct debugfs_regset32 with an optional field to let device > drivers specify the device the registers in the set belong to. This > allows debugfs_show_regset32() to make sure the device is resumed while > its registers are being read. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> LGTM: Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > fs/debugfs/file.c | 8 ++++++++ > include/linux/debugfs.h | 1 + > 2 files changed, 9 insertions(+) > > diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c > index dede25247b81f72a..5e52d68421c678f2 100644 > --- a/fs/debugfs/file.c > +++ b/fs/debugfs/file.c > @@ -18,6 +18,7 @@ > #include <linux/slab.h> > #include <linux/atomic.h> > #include <linux/device.h> > +#include <linux/pm_runtime.h> > #include <linux/poll.h> > #include <linux/security.h> > > @@ -1057,7 +1058,14 @@ static int debugfs_show_regset32(struct seq_file *s, void *data) > { > struct debugfs_regset32 *regset = s->private; > > + if (regset->dev) > + pm_runtime_get_sync(regset->dev); > + > debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, ""); > + > + if (regset->dev) > + pm_runtime_put(regset->dev); > + > return 0; > } > > diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h > index bf9b6cafa4c26a68..5d0783ae09f365ac 100644 > --- a/include/linux/debugfs.h > +++ b/include/linux/debugfs.h > @@ -35,6 +35,7 @@ struct debugfs_regset32 { > const struct debugfs_reg32 *regs; > int nregs; > void __iomem *base; > + struct device *dev; /* Optional device for Runtime PM */ > }; > > extern struct dentry *arch_debugfs_dir; > -- > 2.17.1 >
On Fri, Jan 24, 2020 at 02:29:56PM +0100, Geert Uytterhoeven wrote: > Hardware registers of devices under control of power management cannot > be accessed at all times. If such a device is suspended, register > accesses may lead to undefined behavior, like reading bogus values, or > causing exceptions or system locks. > > Extend struct debugfs_regset32 with an optional field to let device > drivers specify the device the registers in the set belong to. This > allows debugfs_show_regset32() to make sure the device is resumed while > its registers are being read. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > fs/debugfs/file.c | 8 ++++++++ > include/linux/debugfs.h | 1 + > 2 files changed, 9 insertions(+) > > diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c > index dede25247b81f72a..5e52d68421c678f2 100644 > --- a/fs/debugfs/file.c > +++ b/fs/debugfs/file.c > @@ -18,6 +18,7 @@ > #include <linux/slab.h> > #include <linux/atomic.h> > #include <linux/device.h> > +#include <linux/pm_runtime.h> > #include <linux/poll.h> > #include <linux/security.h> > > @@ -1057,7 +1058,14 @@ static int debugfs_show_regset32(struct seq_file *s, void *data) > { > struct debugfs_regset32 *regset = s->private; > > + if (regset->dev) > + pm_runtime_get_sync(regset->dev); > + > debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, ""); > + > + if (regset->dev) > + pm_runtime_put(regset->dev); > + > return 0; > } > > diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h > index bf9b6cafa4c26a68..5d0783ae09f365ac 100644 > --- a/include/linux/debugfs.h > +++ b/include/linux/debugfs.h > @@ -35,6 +35,7 @@ struct debugfs_regset32 { > const struct debugfs_reg32 *regs; > int nregs; > void __iomem *base; > + struct device *dev; /* Optional device for Runtime PM */ > }; > > extern struct dentry *arch_debugfs_dir; Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index dede25247b81f72a..5e52d68421c678f2 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -18,6 +18,7 @@ #include <linux/slab.h> #include <linux/atomic.h> #include <linux/device.h> +#include <linux/pm_runtime.h> #include <linux/poll.h> #include <linux/security.h> @@ -1057,7 +1058,14 @@ static int debugfs_show_regset32(struct seq_file *s, void *data) { struct debugfs_regset32 *regset = s->private; + if (regset->dev) + pm_runtime_get_sync(regset->dev); + debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, ""); + + if (regset->dev) + pm_runtime_put(regset->dev); + return 0; } diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index bf9b6cafa4c26a68..5d0783ae09f365ac 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -35,6 +35,7 @@ struct debugfs_regset32 { const struct debugfs_reg32 *regs; int nregs; void __iomem *base; + struct device *dev; /* Optional device for Runtime PM */ }; extern struct dentry *arch_debugfs_dir;
Hardware registers of devices under control of power management cannot be accessed at all times. If such a device is suspended, register accesses may lead to undefined behavior, like reading bogus values, or causing exceptions or system locks. Extend struct debugfs_regset32 with an optional field to let device drivers specify the device the registers in the set belong to. This allows debugfs_show_regset32() to make sure the device is resumed while its registers are being read. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- fs/debugfs/file.c | 8 ++++++++ include/linux/debugfs.h | 1 + 2 files changed, 9 insertions(+)