| Message ID | 8661d652968d050489852ccb50df5ad4cc048900.1623780059.git.geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add generic-support for linux,elfcorehdr and fix riscv | expand |
On Tue, Jun 15, 2021 at 12:17 PM Geert Uytterhoeven <geert+renesas@glider.be> wrote: > > There are two methods to specify the location of the elf core header: > using the "elfcorehdr=" kernel parameter, as handled by generic code in > kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the > "/chosen" node in the Device Tree, as handled by architecture-specific > code in arch/arm64/mm/init.c. > > Extend support for "linux,elfcorehdr" to all platforms supporting DT by > adding platform-agnostic handling for parsing this property to the FDT > core code. This can co-exist safely with the architecture-specific > handling, until the latter has been removed. > > This requires moving the call to of_scan_flat_dt() up, as the code > scanning the "/chosen" node now needs to be aware of the values of > "#address-cells" and "#size-cells". > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > Documentation/devicetree/bindings/chosen.txt | 6 ++-- > drivers/of/fdt.c | 37 ++++++++++++++++++-- > 2 files changed, 37 insertions(+), 6 deletions(-) > > diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt > index 45e79172a646c537..5b0b94eb2d04e79d 100644 > --- a/Documentation/devicetree/bindings/chosen.txt > +++ b/Documentation/devicetree/bindings/chosen.txt > @@ -106,9 +106,9 @@ respectively, of the root node. > linux,elfcorehdr > ---------------- > > -This property (currently used only on arm64) holds the memory range, > -the address and the size, of the elf core header which mainly describes > -the panicked kernel's memory layout as PT_LOAD segments of elf format. > +This property holds the memory range, the address and the size, of the elf > +core header which mainly describes the panicked kernel's memory layout as > +PT_LOAD segments of elf format. > e.g. > > / { > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index a03d43f95495d8e1..f13db831c8028cce 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -8,6 +8,7 @@ > > #define pr_fmt(fmt) "OF: fdt: " fmt > > +#include <linux/crash_dump.h> > #include <linux/crc32.h> > #include <linux/kernel.h> > #include <linux/initrd.h> > @@ -909,6 +910,35 @@ static inline void early_init_dt_check_for_initrd(unsigned long node) > } > #endif /* CONFIG_BLK_DEV_INITRD */ > > +#ifdef CONFIG_CRASH_DUMP > +/** > + * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat > + * tree > + * @node: reference to node containing elfcorehdr location ('chosen') > + */ > +static void __init early_init_dt_check_for_elfcorehdr(unsigned long node) > +{ > + const __be32 *prop; > + int len; > + > + pr_debug("Looking for elfcorehdr property... "); > + > + prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len); > + if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells))) > + return; > + > + elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop); > + elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop); If these declarations were moved outside the '#ifdef CONFIG_CRASH_DUMP' in crash_dump.h, then IS_ENABLED() could be used in this function. > + > + pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n", > + elfcorehdr_addr, elfcorehdr_size); > +} > +#else > +static inline void early_init_dt_check_for_elfcorehdr(unsigned long node) > +{ > +} > +#endif > + > #ifdef CONFIG_SERIAL_EARLYCON > > int __init early_init_dt_scan_chosen_stdout(void) > @@ -1057,6 +1087,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, > return 0; > > early_init_dt_check_for_initrd(node); > + early_init_dt_check_for_elfcorehdr(node); > > /* Retrieve command line */ > p = of_get_flat_dt_prop(node, "bootargs", &l); > @@ -1201,14 +1232,14 @@ void __init early_init_dt_scan_nodes(void) > { > int rc = 0; > > + /* Initialize {size,address}-cells info */ > + of_scan_flat_dt(early_init_dt_scan_root, NULL); > + > /* Retrieve various information from the /chosen node */ > rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line); > if (!rc) > pr_warn("No chosen node found, continuing without\n"); > > - /* Initialize {size,address}-cells info */ > - of_scan_flat_dt(early_init_dt_scan_root, NULL); > - > /* Setup memory, calling early_init_dt_add_memory_arch */ > of_scan_flat_dt(early_init_dt_scan_memory, NULL); > } > -- > 2.25.1 >
Στις 2021-06-15 21:17, Geert Uytterhoeven έγραψε: > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c I believe drivers/of/kexec.c is better suited for this.
Hi Nick, On Wed, Jun 16, 2021 at 1:28 AM Nick Kossifidis <mick@ics.forth.gr> wrote: > > Στις 2021-06-15 21:17, Geert Uytterhoeven έγραψε: > > > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > > I believe drivers/of/kexec.c is better suited for this. From an earlier response from me to a comment from Rob: | > Also, note that there is now a drivers/of/kexec.c (in -next) though | > not sure if all this would go there or stay in fdt.c with the rest of | > the memory parsing. | | It's gonna be the latter, as that file handles the FDT during early | kernel startup, for both normal and kdump kernels. | | Despite the name, drivers/of/kexec.c is not for kexec, but for | kexec_file. This is the "new" fancy syscall that prepares the DTB | for the new kernel itself, unlike the classic kexec syscall, where | userspace is responsible for preparing the DTB for the new kernel. Gr{oetje,eeting}s, Geert
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt index 45e79172a646c537..5b0b94eb2d04e79d 100644 --- a/Documentation/devicetree/bindings/chosen.txt +++ b/Documentation/devicetree/bindings/chosen.txt @@ -106,9 +106,9 @@ respectively, of the root node. linux,elfcorehdr ---------------- -This property (currently used only on arm64) holds the memory range, -the address and the size, of the elf core header which mainly describes -the panicked kernel's memory layout as PT_LOAD segments of elf format. +This property holds the memory range, the address and the size, of the elf +core header which mainly describes the panicked kernel's memory layout as +PT_LOAD segments of elf format. e.g. / { diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index a03d43f95495d8e1..f13db831c8028cce 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -8,6 +8,7 @@ #define pr_fmt(fmt) "OF: fdt: " fmt +#include <linux/crash_dump.h> #include <linux/crc32.h> #include <linux/kernel.h> #include <linux/initrd.h> @@ -909,6 +910,35 @@ static inline void early_init_dt_check_for_initrd(unsigned long node) } #endif /* CONFIG_BLK_DEV_INITRD */ +#ifdef CONFIG_CRASH_DUMP +/** + * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat + * tree + * @node: reference to node containing elfcorehdr location ('chosen') + */ +static void __init early_init_dt_check_for_elfcorehdr(unsigned long node) +{ + const __be32 *prop; + int len; + + pr_debug("Looking for elfcorehdr property... "); + + prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len); + if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells))) + return; + + elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop); + elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop); + + pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n", + elfcorehdr_addr, elfcorehdr_size); +} +#else +static inline void early_init_dt_check_for_elfcorehdr(unsigned long node) +{ +} +#endif + #ifdef CONFIG_SERIAL_EARLYCON int __init early_init_dt_scan_chosen_stdout(void) @@ -1057,6 +1087,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, return 0; early_init_dt_check_for_initrd(node); + early_init_dt_check_for_elfcorehdr(node); /* Retrieve command line */ p = of_get_flat_dt_prop(node, "bootargs", &l); @@ -1201,14 +1232,14 @@ void __init early_init_dt_scan_nodes(void) { int rc = 0; + /* Initialize {size,address}-cells info */ + of_scan_flat_dt(early_init_dt_scan_root, NULL); + /* Retrieve various information from the /chosen node */ rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line); if (!rc) pr_warn("No chosen node found, continuing without\n"); - /* Initialize {size,address}-cells info */ - of_scan_flat_dt(early_init_dt_scan_root, NULL); - /* Setup memory, calling early_init_dt_add_memory_arch */ of_scan_flat_dt(early_init_dt_scan_memory, NULL); }
There are two methods to specify the location of the elf core header: using the "elfcorehdr=" kernel parameter, as handled by generic code in kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the "/chosen" node in the Device Tree, as handled by architecture-specific code in arch/arm64/mm/init.c. Extend support for "linux,elfcorehdr" to all platforms supporting DT by adding platform-agnostic handling for parsing this property to the FDT core code. This can co-exist safely with the architecture-specific handling, until the latter has been removed. This requires moving the call to of_scan_flat_dt() up, as the code scanning the "/chosen" node now needs to be aware of the values of "#address-cells" and "#size-cells". Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- Documentation/devicetree/bindings/chosen.txt | 6 ++-- drivers/of/fdt.c | 37 ++++++++++++++++++-- 2 files changed, 37 insertions(+), 6 deletions(-)