From 2229a12b64a4df7128b6e2d86be2688f8c76efec Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 17 Jun 2020 10:25:05 +0200 Subject: ACPI: tables: avoid relocations for table signature array On architectures that implement KASLR using the ELF native RELA relocation format (such as arm64), every absolute reference in the code incurs an overhead of 24 bytes in the .rela section. So storing a 41 element array of 4 character signature strings using an array of pointer-to-char incurs an 8x overhead (32 bytes per entry => ~1500 bytes), and given the fixed length of the entries, and the fact that the array is only used locally, it is much better to use an array of arrays here, which gets rid of the overhead entirely. While at it, make it __initconst, as it is never referenced except from __init code. Signed-off-by: Ard Biesheuvel Signed-off-by: Rafael J. Wysocki --- drivers/acpi/tables.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/acpi/tables.c') diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 0e905c3d1645..ada36bc40c2b 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -490,7 +490,7 @@ static u8 __init acpi_table_checksum(u8 *buffer, u32 length) } /* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */ -static const char * const table_sigs[] = { +static const char table_sigs[][ACPI_NAMESEG_SIZE] __initconst = { ACPI_SIG_BERT, ACPI_SIG_BGRT, 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, @@ -501,7 +501,7 @@ static const char * const table_sigs[] = { ACPI_SIG_WDDT, ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT, ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, ACPI_SIG_IORT, ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT, - ACPI_SIG_NHLT, NULL }; + ACPI_SIG_NHLT }; #define ACPI_HEADER_SIZE sizeof(struct acpi_table_header) @@ -548,11 +548,11 @@ void __init acpi_table_upgrade(void) table = file.data; - for (sig = 0; table_sigs[sig]; sig++) + for (sig = 0; sig < ARRAY_SIZE(table_sigs); sig++) if (!memcmp(table->signature, table_sigs[sig], 4)) break; - if (!table_sigs[sig]) { + if (sig >= ARRAY_SIZE(table_sigs)) { pr_err("ACPI OVERRIDE: Unknown signature [%s%s]\n", cpio_path, file.name); continue; -- cgit v1.2.3 From 24194a7e03f46f08579e3094417e448a92aff2b4 Mon Sep 17 00:00:00 2001 From: Hanjun Guo Date: Tue, 21 Jul 2020 17:59:04 +0800 Subject: ACPI: tables: Remove the duplicated checks for acpi_parse_entries_array() acpi_disabled, pointer id and table_header are checked in acpi_table_parse_entries_array(), and acpi_parse_entries_array() is only called by acpi_table_parse_entries_array(), so those checks in acpi_parse_entries_array() are duplicate. Remove those duplicated checks and move the table_size check to acpi_table_parse_entries_array() as well. Signed-off-by: Hanjun Guo Signed-off-by: Rafael J. Wysocki --- drivers/acpi/tables.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) (limited to 'drivers/acpi/tables.c') diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index ada36bc40c2b..e48690a006a4 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -292,20 +292,6 @@ static int __init acpi_parse_entries_array(char *id, unsigned long table_size, int errs = 0; int i; - if (acpi_disabled) - return -ENODEV; - - if (!id) - return -EINVAL; - - if (!table_size) - return -EINVAL; - - if (!table_header) { - pr_warn("%4.4s not present\n", id); - return -ENODEV; - } - table_end = (unsigned long)table_header + table_header->length; /* Parse all entries looking for a match. */ @@ -371,6 +357,9 @@ int __init acpi_table_parse_entries_array(char *id, if (!id) return -EINVAL; + if (!table_size) + return -EINVAL; + if (!strncmp(id, ACPI_SIG_MADT, 4)) instance = acpi_apic_instance; -- cgit v1.2.3