| Message ID | 20211208151123.29313-3-vincent.whitchurch@axis.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Devicetree support for UML | expand |
On Wed, Dec 08, 2021 at 04:11:23PM +0100, Vincent Whitchurch wrote: > Add a dtb=<filename> option to boot UML with a devicetree blob. This > can be used for testing driver code using UML. Neat! > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> > --- > arch/um/Kconfig | 1 + > arch/um/kernel/Makefile | 1 + > arch/um/kernel/dtb.c | 41 ++++++++++++++++++++++++++++++++++++++++ > arch/um/kernel/um_arch.c | 3 +++ > arch/um/kernel/um_arch.h | 6 ++++++ > 5 files changed, 52 insertions(+) > create mode 100644 arch/um/kernel/dtb.c > > diff --git a/arch/um/Kconfig b/arch/um/Kconfig > index c18b45f75d41..1cf7ef3a2b81 100644 > --- a/arch/um/Kconfig > +++ b/arch/um/Kconfig > @@ -18,6 +18,7 @@ config UML > select HAVE_DEBUG_KMEMLEAK > select HAVE_DEBUG_BUGVERBOSE > select NO_DMA if !UML_DMA_EMULATION > + select OF_EARLY_FLATTREE > select GENERIC_IRQ_SHOW > select GENERIC_CPU_DEVICES > select HAVE_GCC_PLUGINS > diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile > index 92692bfef7ae..ebd0cca3ff26 100644 > --- a/arch/um/kernel/Makefile > +++ b/arch/um/kernel/Makefile > @@ -22,6 +22,7 @@ obj-y += load_file.o > > obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o > obj-$(CONFIG_GPROF) += gprof_syms.o > +obj-$(CONFIG_OF) += dtb.o > obj-$(CONFIG_EARLY_PRINTK) += early_printk.o > obj-$(CONFIG_STACKTRACE) += stacktrace.o > obj-$(CONFIG_GENERIC_PCI_IOMAP) += ioport.o > diff --git a/arch/um/kernel/dtb.c b/arch/um/kernel/dtb.c > new file mode 100644 > index 000000000000..ca69d72025f3 > --- /dev/null > +++ b/arch/um/kernel/dtb.c > @@ -0,0 +1,41 @@ > +// SPDX-License-Identifier: GPL-2.0-only > + > +#include <linux/init.h> > +#include <linux/of_fdt.h> > +#include <linux/printk.h> > +#include <linux/memblock.h> > +#include <init.h> > + > +#include "um_arch.h" > + > +static char *dtb __initdata; > + > +void uml_dtb_init(void) > +{ > + long long size; > + void *area; > + > + area = uml_load_file(dtb, &size); > + if (!area) > + return; > + > + if (!early_init_dt_scan(area)) { > + pr_err("invalid DTB %s\n", dtb); > + memblock_free(area, size); > + return; > + } > + > + unflatten_device_tree(); > + early_init_fdt_scan_reserved_mem(); These should be reversed. early_init_fdt_scan_reserved_mem() works on the flat tree. Reserved memory needs to be reserved before unflatten_device_tree() starts allocating memory. Though I imagine that doesn't really matter for UML. Also, does the dtb end up in permanently allocated memory (i.e. not init)? It needs to be if not. Rob
On Fri, Jan 14, 2022 at 02:49:09PM +0100, Rob Herring wrote: > On Wed, Dec 08, 2021 at 04:11:23PM +0100, Vincent Whitchurch wrote: > > --- /dev/null > > +++ b/arch/um/kernel/dtb.c > > @@ -0,0 +1,41 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > + > > +#include <linux/init.h> > > +#include <linux/of_fdt.h> > > +#include <linux/printk.h> > > +#include <linux/memblock.h> > > +#include <init.h> > > + > > +#include "um_arch.h" > > + > > +static char *dtb __initdata; > > + > > +void uml_dtb_init(void) > > +{ > > + long long size; > > + void *area; > > + > > + area = uml_load_file(dtb, &size); > > + if (!area) > > + return; > > + > > + if (!early_init_dt_scan(area)) { > > + pr_err("invalid DTB %s\n", dtb); > > + memblock_free(area, size); > > + return; > > + } > > + > > + unflatten_device_tree(); > > + early_init_fdt_scan_reserved_mem(); > > These should be reversed. early_init_fdt_scan_reserved_mem() works on > the flat tree. Reserved memory needs to be reserved before > unflatten_device_tree() starts allocating memory. Though I imagine that > doesn't really matter for UML. I only tested dynamic allocation of reserved memory, and that, unsuprisingly, works regardless of the order. But I'll send a patch to change it. > Also, does the dtb end up in permanently allocated memory (i.e. not > init)? It needs to be if not. The dtb is allocated with memblock_alloc() in arch/um/kernel/load_file.c and is never freed (except on an error from early_init_dt_scan() as in the above hunk), so I think this is already taken care of.
diff --git a/arch/um/Kconfig b/arch/um/Kconfig index c18b45f75d41..1cf7ef3a2b81 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -18,6 +18,7 @@ config UML select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_BUGVERBOSE select NO_DMA if !UML_DMA_EMULATION + select OF_EARLY_FLATTREE select GENERIC_IRQ_SHOW select GENERIC_CPU_DEVICES select HAVE_GCC_PLUGINS diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile index 92692bfef7ae..ebd0cca3ff26 100644 --- a/arch/um/kernel/Makefile +++ b/arch/um/kernel/Makefile @@ -22,6 +22,7 @@ obj-y += load_file.o obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o obj-$(CONFIG_GPROF) += gprof_syms.o +obj-$(CONFIG_OF) += dtb.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-$(CONFIG_STACKTRACE) += stacktrace.o obj-$(CONFIG_GENERIC_PCI_IOMAP) += ioport.o diff --git a/arch/um/kernel/dtb.c b/arch/um/kernel/dtb.c new file mode 100644 index 000000000000..ca69d72025f3 --- /dev/null +++ b/arch/um/kernel/dtb.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include <linux/init.h> +#include <linux/of_fdt.h> +#include <linux/printk.h> +#include <linux/memblock.h> +#include <init.h> + +#include "um_arch.h" + +static char *dtb __initdata; + +void uml_dtb_init(void) +{ + long long size; + void *area; + + area = uml_load_file(dtb, &size); + if (!area) + return; + + if (!early_init_dt_scan(area)) { + pr_err("invalid DTB %s\n", dtb); + memblock_free(area, size); + return; + } + + unflatten_device_tree(); + early_init_fdt_scan_reserved_mem(); +} + +static int __init uml_dtb_setup(char *line, int *add) +{ + dtb = line; + return 0; +} + +__uml_setup("dtb=", uml_dtb_setup, +"dtb=<file>\n" +" Boot the kernel with the devicetree blob from the specified file.\n" +); diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 54447690de11..abceeabe29b9 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -29,6 +29,8 @@ #include <mem_user.h> #include <os.h> +#include "um_arch.h" + #define DEFAULT_COMMAND_LINE_ROOT "root=98:0" #define DEFAULT_COMMAND_LINE_CONSOLE "console=tty" @@ -407,6 +409,7 @@ void __init setup_arch(char **cmdline_p) stack_protections((unsigned long) &init_thread_info); setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem); mem_total_pages(physmem_size, iomem_size, highmem); + uml_dtb_init(); read_initrd(); paging_init(); diff --git a/arch/um/kernel/um_arch.h b/arch/um/kernel/um_arch.h index b195df3a09a0..1e07fb7ee35e 100644 --- a/arch/um/kernel/um_arch.h +++ b/arch/um/kernel/um_arch.h @@ -5,4 +5,10 @@ extern void * __init uml_load_file(const char *filename, unsigned long long *size); +#ifdef CONFIG_OF +extern void __init uml_dtb_init(void); +#else +static inline void uml_dtb_init(void) { } +#endif + #endif
Add a dtb=<filename> option to boot UML with a devicetree blob. This can be used for testing driver code using UML. Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> --- arch/um/Kconfig | 1 + arch/um/kernel/Makefile | 1 + arch/um/kernel/dtb.c | 41 ++++++++++++++++++++++++++++++++++++++++ arch/um/kernel/um_arch.c | 3 +++ arch/um/kernel/um_arch.h | 6 ++++++ 5 files changed, 52 insertions(+) create mode 100644 arch/um/kernel/dtb.c