On Fri, Sep 21, 2012 at 6:28 AM, Thomas Renninger <trenn@xxxxxxx> wrote: > Details can be found in: > Documentation/acpi/initrd_table_override.txt > > Signed-off-by: Thomas Renninger <trenn@xxxxxxx> > CC: eric.piel@xxxxxxxxxxxxxxxx > CC: vojcek@xxxxxxx > CC: Lin Ming <ming.m.lin@xxxxxxxxx> > CC: lenb@xxxxxxxxxx > CC: robert.moore@xxxxxxxxx > CC: hpa@xxxxxxxxx > CC: yinghai@xxxxxxxxxx > --- > Documentation/acpi/initrd_table_override.txt | 122 +++++++++++++++ > arch/x86/kernel/setup.c | 4 + > drivers/acpi/Kconfig | 9 + > drivers/acpi/osl.c | 203 ++++++++++++++++++++++++-- > include/linux/acpi.h | 4 + > 5 files changed, 331 insertions(+), 11 deletions(-) > create mode 100644 Documentation/acpi/initrd_table_override.txt > > diff --git a/Documentation/acpi/initrd_table_override.txt b/Documentation/acpi/initrd_table_override.txt > new file mode 100644 > index 0000000..b550831 > --- /dev/null > +++ b/Documentation/acpi/initrd_table_override.txt > @@ -0,0 +1,122 @@ > +Overriding ACPI tables via initrd > +================================= > + > +1) Introduction (What is this about) > +2) What is this for > +3) How does it work > +4) References (Where to retrieve userspace tools) > + > +1) What is this about > +--------------------- > + > +If ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible to > +override nearly any ACPI table provided by the BIOS with an instrumented, > +modified one. > + > +For a full list of ACPI tables that can be overridden, take a look at > +the char *table_sigs[MAX_ACPI_SIGNATURE]; definition in drivers/acpi/osl.c > +All ACPI tables iasl (Intel's ACPI compiler and disassembler) knows should > +be overridable, except: > + - ACPI_SIG_RSDP (has a signature of 6 bytes) > + - ACPI_SIG_FACS (does not have an ordinary ACPI table header) > +Both could get implemented as well. > + > + > +2) What is this for > +------------------- > + > +Please keep in mind that this is a debug option. > +ACPI tables should not get overridden for productive use. > +If BIOS ACPI tables are overridden the kernel will get tainted with the > +TAINT_OVERRIDDEN_ACPI_TABLE flag. > +Complain to your platform/BIOS vendor if you find a bug which is that sever > +that a workaround is not accepted in the Linus kernel. > + > +Still, it can and should be enabled in any kernel, because: > + - There is no functional change with not instrumented initrds > + - It provides a powerful feature to easily debug and test ACPI BIOS table > + compatibility with the Linux kernel. > + > +Until now it was only possible to override the DSDT by compiling it into > +the kernel. This is a nightmare when trying to work on ACPI related bugs > +and a lot bugs got stuck because of that. > +Even for people with enough kernel knowledge, building a kernel to try out > +things is very time consuming. Also people may have to browse and modify the > +ACPI interpreter code to find a possible BIOS bug. With this feature, people > +can correct the ACPI tables and try out quickly whether this is the root cause > +that needs to get addressed in the kernel. > + > +This could even ease up testing for BIOS providers who could flush their BIOS > +to test, but overriding table via initrd is much easier and quicker. > +For example one could prepare different initrds overriding NUMA tables with > +different affinity settings. Set up a script, let the machine reboot and > +run tests over night and one can get a picture how these settings influence > +the Linux kernel and which values are best. > + > +People can instrument the dynamic ACPI (ASL) code (for example with debug > +statements showing up in syslog when the ACPI code is processed, etc.), > +to better understand BIOS to OS interfaces, to hunt down ACPI BIOS code related > +bugs quickly or to easier develop ACPI based drivers. > + > +Intstrumenting ACPI code in SSDTs is now much easier. Before, one had to copy > +all SSDTs into the DSDT to compile it into the kernel for testing > +(because only DSDT could get overridden). That's what the acpi_no_auto_ssdt > +boot param is for: the BIOS provided SSDTs are ignored and all have to get > +copied into the DSDT, complicated and time consuming. > + > +Much more use cases, depending on which ACPI parts you are working on... > + > + > +3) How does it work > +------------------- > + > +# Extract the machine's ACPI tables: > +cd /tmp > +acpidump >acpidump > +acpixtract -a acpidump > +# Disassemble, modify and recompile them: > +iasl -d *.dat > +# For example add this statement into a _PRT (PCI Routing Table) function > +# of the DSDT: > +Store("HELLO WORLD", debug) > +iasl -sa dsdt.dsl > +# Add the raw ACPI tables to an uncompressed cpio archive. > +# They must be put into a /kernel/firmware/acpi directory inside the > +# cpio archive. > +# The uncompressed cpio archive must be the first. > +# Other, typically compressed cpio archives, must be > +# concatenated on top of the uncompressed one. > +mkdir -p kernel/firmware/acpi > +cp dsdt.aml kernel/firmware/acpi > +# A maximum of: #define ACPI_OVERRIDE_TABLES 10 > +# tables are currently allowed (see osl.c): > +iasl -sa facp.dsl > +iasl -sa ssdt1.dsl > +cp facp.aml kernel/firmware/acpi > +cp ssdt1.aml kernel/firmware/acpi > +# Create the uncompressed cpio archive and concatenate the orginal initrd > +# on top: > +find kernel | cpio -H newc --create > /boot/instrumented_initrd > +cat /boot/initrd >>/boot/instrumented_initrd > +# reboot with increased acpi debug level, e.g. boot params: > +acpi.debug_level=0x2 acpi.debug_layer=0xFFFFFFFF > +# and check your syslog: > +[ 1.268089] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT] > +[ 1.272091] [ACPI Debug] String [0x0B] "HELLO WORLD" > + > +iasl is able to disassemble and recompile quite a lot different, > +also static ACPI tables. > + > +4) Where to retrieve userspace tools > +------------------------------------ > + > +iasl and acpixtract are part of Intel's ACPICA project: > +http://acpica.org/ > +and should be packaged by distributions (for example in the acpica package > +on SUSE). > + > +acpidump can be found in Len Browns pmtools: > +ftp://kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools/acpidump > +This tool is also part of the acpica package on SUSE. > +Alternatively, used ACPI tables can be retrieved via sysfs in latest kernels: > +/sys/firmware/acpi/tables > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index f4b9b80..6a91058 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -941,6 +941,10 @@ void __init setup_arch(char **cmdline_p) > > reserve_initrd(); > > +#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE > + acpi_initrd_override((void *)initrd_start, initrd_end - initrd_start); > +#endif > + could use #ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE void acpi_initrd_override(void *data, size_t size); #else static inline void acpi_initrd_override(void *data, size_t size) { } #endif in one header file to avoid MACRO in setup.c > reserve_crashkernel(); > > vsmp_init(); > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig > index 8099895..a508f77 100644 > --- a/drivers/acpi/Kconfig > +++ b/drivers/acpi/Kconfig > @@ -261,6 +261,15 @@ config ACPI_CUSTOM_DSDT > bool > default ACPI_CUSTOM_DSDT_FILE != "" > > +config ACPI_INITRD_TABLE_OVERRIDE > + bool > + default y > + help > + This option provides functionality to override arbitrary ACPI tables > + via initrd. No functional change if no ACPI tables are passed via > + initrd, therefore it's safe to say Y. > + See Documentation/acpi/initrd_table_override.txt for details > + > config ACPI_BLACKLIST_YEAR > int "Disable ACPI for systems before Jan 1st this year" if X86_32 > default 0 > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c > index 9eaf708..ba7560f 100644 > --- a/drivers/acpi/osl.c > +++ b/drivers/acpi/osl.c > @@ -534,6 +534,137 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val, > return AE_OK; > } > > +#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE > +#include <linux/earlycpio.h> > +#include <linux/memblock.h> > + > +#include <asm/e820.h> > + > +static u64 acpi_tables_addr; > +static int all_tables_size; > + > +/* Copied from acpica/tbutils.c:acpi_tb_checksum() */ > +u8 __init acpi_table_checksum(u8 *buffer, u32 length) > +{ > + u8 sum = 0; > + u8 *end = buffer + length; > + > + while (buffer < end) > + sum = (u8) (sum + *(buffer++)); > + return sum; > +} > + > +/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */ > +static const char * const table_sigs[] = { > + ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ, > + ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT, > + ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF, > + ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET, > + ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI, > + ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA, > + ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT, > + ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT, > + ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL }; > + > +/* Non-fatal errors: Affected tables/files are ignored */ > +#define INVALID_TABLE(x, path, name) \ > + { pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); continue; } > + > +#define ACPI_HEADER_SIZE sizeof(struct acpi_table_header) > + > +/* Must not increase 10 or needs code modifcation below */ > +#define ACPI_OVERRIDE_TABLES 10 > + > +void __init acpi_initrd_override(void *data, size_t size) > +{ > + int sig, no, table_nr = 0, total_offset = 0; > + long offset = 0; > + struct acpi_table_header *table; > + char cpio_path[32] = "kernel/firmware/acpi/"; > + struct cpio_data file; > + struct cpio_data early_initrd_files[ACPI_OVERRIDE_TABLES]; > + char *p; > + > + if (data == NULL || size == 0) > + return; > + > + for (no = 0; no < ACPI_OVERRIDE_TABLES; no++) { > + file = find_cpio_data(cpio_path, data, size, &offset); > + if (!file.data) > + break; > + > + data += offset; > + size -= offset; > + > + if (file.size < sizeof(struct acpi_table_header)) > + INVALID_TABLE("Table smaller than ACPI header", > + cpio_path, file.name); > + > + table = file.data; > + > + for (sig = 0; table_sigs[sig]; sig++) > + if (!memcmp(table->signature, table_sigs[sig], 4)) > + break; > + > + if (!table_sigs[sig]) > + INVALID_TABLE("Unknown signature", > + cpio_path, file.name); > + if (file.size != table->length) > + INVALID_TABLE("File length does not match table length", > + cpio_path, file.name); > + if (acpi_table_checksum(file.data, table->length)) > + INVALID_TABLE("Bad table checksum", > + cpio_path, file.name); > + > + pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n", > + table->signature, cpio_path, file.name, table->length); > + > + all_tables_size += table->length; > + early_initrd_files[table_nr].data = file.data; > + early_initrd_files[table_nr].size = file.size; > + table_nr++; > + } > + if (table_nr == 0) > + return; > + > + acpi_tables_addr = > + memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT, > + all_tables_size, PAGE_SIZE); > + if (!acpi_tables_addr) { > + WARN_ON(1); > + return; > + } > + /* > + * Only calling e820_add_reserve does not work and the > + * tables are invalid (memory got used) later. > + * memblock_x86_reserve_range works as expected and the tables > + * won't get modified. But it's not enough because ioremap will > + * complain later (used by acpi_os_map_memory) that the pages > + * that should get mapped are not marked "reserved". > + * Both memblock_x86_reserve_range and e820_add_region works fine. > + */ > + memblock_reserve(acpi_tables_addr, acpi_tables_addr + all_tables_size); > + e820_add_region(acpi_tables_addr, all_tables_size, E820_ACPI); > + update_e820(); need to move those arch related to arch/x86 > + p = early_ioremap(acpi_tables_addr, all_tables_size); > + > + for (no = 0; no < table_nr; no++) { > + memcpy(p + total_offset, early_initrd_files[no].data, > + early_initrd_files[no].size); > + total_offset += early_initrd_files[no].size; > + } You may use one loop function, and it could take one call back. callback 1 will get item and size. callback 2 will do the copy... so you can remove hard limit of ACPI_OVERRIDE_TABLES. > + early_iounmap(p, all_tables_size); > +} > +#endif /* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */ > + > +static void acpi_table_taint(struct acpi_table_header *table) > +{ > + pr_warn(PREFIX > + "Override [%4.4s-%8.8s], this is unsafe: tainting kernel\n", > + table->signature, table->oem_table_id); > + add_taint(TAINT_OVERRIDDEN_ACPI_TABLE); > +} > + can you split acpi_table_taint split change to another patch? > acpi_status > acpi_os_table_override(struct acpi_table_header * existing_table, > struct acpi_table_header ** new_table) > @@ -547,24 +678,74 @@ acpi_os_table_override(struct acpi_table_header * existing_table, > if (strncmp(existing_table->signature, "DSDT", 4) == 0) > *new_table = (struct acpi_table_header *)AmlCode; > #endif > - if (*new_table != NULL) { > - printk(KERN_WARNING PREFIX "Override [%4.4s-%8.8s], " > - "this is unsafe: tainting kernel\n", > - existing_table->signature, > - existing_table->oem_table_id); > - add_taint(TAINT_OVERRIDDEN_ACPI_TABLE); > - } > + if (*new_table != NULL) > + acpi_table_taint(existing_table); > return AE_OK; > } > > acpi_status > acpi_os_physical_table_override(struct acpi_table_header *existing_table, > - acpi_physical_address * new_address, > - u32 *new_table_length) > + acpi_physical_address *address, > + u32 *table_length) > { > - return AE_SUPPORT; > -} > +#ifndef CONFIG_ACPI_INITRD_TABLE_OVERRIDE > + *table_length = 0; > + *address = 0; > + return AE_OK; > +#else also could hide macro in header file. > + int table_offset = 0; > + struct acpi_table_header *table; > + > + *table_length = 0; > + *address = 0; > + > + if (!acpi_tables_addr) > + return AE_OK; > + > + do { > + if (table_offset + ACPI_HEADER_SIZE > all_tables_size) { > + WARN_ON(1); > + return AE_OK; > + } > + > + table = acpi_os_map_memory(acpi_tables_addr + table_offset, > + ACPI_HEADER_SIZE); > > + if (table_offset + table->length > all_tables_size) { > + acpi_os_unmap_memory(table, ACPI_HEADER_SIZE); > + WARN_ON(1); > + return AE_OK; > + } > + > + table_offset += table->length; > + > + if (memcmp(existing_table->signature, table->signature, 4)) { > + acpi_os_unmap_memory(table, > + ACPI_HEADER_SIZE); > + continue; > + } > + > + /* Only override tables with matching oem id */ > + if (memcmp(table->oem_table_id, existing_table->oem_table_id, > + ACPI_OEM_TABLE_ID_SIZE)) { > + acpi_os_unmap_memory(table, > + ACPI_HEADER_SIZE); > + continue; > + } > + > + table_offset -= table->length; > + *table_length = table->length; > + acpi_os_unmap_memory(table, ACPI_HEADER_SIZE); > + *address = acpi_tables_addr + table_offset; > + add_taint(TAINT_OVERRIDDEN_ACPI_TABLE); > + break; > + } while (table_offset + ACPI_HEADER_SIZE < all_tables_size); > + > + if (*address != 0) > + acpi_table_taint(existing_table); > + return AE_OK; > +#endif > +} could be split to another patch too. > > static irqreturn_t acpi_irq(int irq, void *dev_id) > { > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 4f2a762..87e2c9e 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -76,6 +76,10 @@ typedef int (*acpi_table_handler) (struct acpi_table_header *table); > > typedef int (*acpi_table_entry_handler) (struct acpi_subtable_header *header, const unsigned long end); > > +#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE > +void __init acpi_initrd_override(void *data, size_t size); could drop __init declaration in header file. > +#endif > + > char * __acpi_map_table (unsigned long phys_addr, unsigned long size); > void __acpi_unmap_table(char *map, unsigned long size); > int early_acpi_boot_init(void); > -- > 1.7.6.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html