With ARMv8.2-LVA architecture extension availability, arm64 hardware which supports this extension can support upto 52-bit virtual addresses. It is specially useful for having a 52-bit user-space virtual address space while the kernel can still retain 48-bit virtual addresses.
Since at the moment we enable the support of this extension in the kernel via a CONFIG flag (CONFIG_ARM64_USER_VA_BITS_52), so there are no clear mechanisms in user-space to determine this CONFIG flag value and use it to determine the user-space VA address range values. 'makedumpfile' can instead use 'MAX_USER_VA_BITS' value to determine the maximum virtual physical address supported by user-space. If 'MAX_USER_VA_BITS' value is greater than 'VA_BITS' than we are running a use-case where user-space is 52-bit and underlying kernel is still 48-bit. The increased 'PTRS_PER_PGD' value for such cases can then be calculated as is done by the underlying kernel (see kernel file 'arch/arm64/include/asm/pgtable-hwdef.h' for details): #define PTRS_PER_PGD (1 << (MAX_USER_VA_BITS - PGDIR_SHIFT)) I have sent a kernel patch upstream to add 'MAX_USER_VA_BITS' to vmcoreinfo for arm64 (see [0]). This patch is in accordance with ARMv8 Architecture Reference Manual version D.a [0]. http://lists.infradead.org/pipermail/kexec/2019-February/022411.html Signed-off-by: Bhupesh Sharma <[email protected]> --- arch/arm64.c | 105 +++++++++++++++++++++++++++++++++++++++++---------------- makedumpfile.c | 2 ++ makedumpfile.h | 1 + 3 files changed, 79 insertions(+), 29 deletions(-) diff --git a/arch/arm64.c b/arch/arm64.c index 29247a7fa7db..a9abfa74574c 100644 --- a/arch/arm64.c +++ b/arch/arm64.c @@ -47,6 +47,7 @@ typedef struct { static int lpa_52_bit_support_available; static int pgtable_level; static int va_bits; +static int max_user_va_bits; static unsigned long kimage_voffset; #define SZ_4K 4096 @@ -120,7 +121,7 @@ typedef unsigned long pgdval_t; #define PGDIR_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - (pgtable_level)) #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT) #define PGDIR_MASK (~(PGDIR_SIZE-1)) -#define PTRS_PER_PGD (1 << ((va_bits) - PGDIR_SHIFT)) +#define PTRS_PER_PGD (1 << ((max_user_va_bits) - PGDIR_SHIFT)) /* * Section address mask and size definitions. @@ -402,6 +403,46 @@ get_stext_symbol(void) return(found ? kallsym : FALSE); } +static int +get_va_bits_from_stext_arm64(void) +{ + ulong _stext; + + _stext = get_stext_symbol(); + if (!_stext) { + ERRMSG("Can't get the symbol of _stext.\n"); + return FALSE; + } + + /* Derive va_bits as per arch/arm64/Kconfig */ + if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) { + va_bits = 36; + } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) { + va_bits = 39; + } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) { + va_bits = 42; + } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) { + va_bits = 47; + } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) { + va_bits = 48; + } else { + ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); + return FALSE; + } + + DEBUG_MSG("va_bits : %d\n", va_bits); + + return TRUE; +} + +static void +get_page_offset_arm64(void) +{ + info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1); + + DEBUG_MSG("page_offset : %lx\n", info->page_offset); +} + int get_machdep_info_arm64(void) { @@ -416,8 +457,37 @@ get_machdep_info_arm64(void) /* Check if va_bits is still not initialized. If still 0, call * get_versiondep_info() to initialize the same. */ + if (NUMBER(VA_BITS) != NOT_FOUND_NUMBER) { + va_bits = NUMBER(VA_BITS); + DEBUG_MSG("va_bits : %d (vmcoreinfo)\n", + va_bits); + } + + /* Check if va_bits is still not initialized. If still 0, call + * get_versiondep_info() to initialize the same from _stext + * symbol. + */ if (!va_bits) - get_versiondep_info_arm64(); + if (get_va_bits_from_stext_arm64() == ERROR) + return ERROR; + + get_page_offset_arm64(); + + if (NUMBER(MAX_USER_VA_BITS) != NOT_FOUND_NUMBER) { + max_user_va_bits = NUMBER(MAX_USER_VA_BITS); + DEBUG_MSG("max_user_va_bits : %d (vmcoreinfo)\n", + max_user_va_bits); + } + + /* Check if max_user_va_bits is still not initialized. + * If still 0, its not available in vmcoreinfo and its + * safe to initialize it with va_bits. + */ + if (!max_user_va_bits) { + max_user_va_bits = va_bits; + DEBUG_MSG("max_user_va_bits : %d (default = va_bits)\n", + max_user_va_bits); + } if (!calculate_plat_config()) { ERRMSG("Can't determine platform config values\n"); @@ -455,34 +525,11 @@ get_xen_info_arm64(void) int get_versiondep_info_arm64(void) { - ulong _stext; - - _stext = get_stext_symbol(); - if (!_stext) { - ERRMSG("Can't get the symbol of _stext.\n"); - return FALSE; - } - - /* Derive va_bits as per arch/arm64/Kconfig */ - if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) { - va_bits = 36; - } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) { - va_bits = 39; - } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) { - va_bits = 42; - } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) { - va_bits = 47; - } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) { - va_bits = 48; - } else { - ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); - return FALSE; - } - - info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1); + if (!va_bits) + if (get_va_bits_from_stext_arm64() == ERROR) + return ERROR; - DEBUG_MSG("va_bits : %d\n", va_bits); - DEBUG_MSG("page_offset : %lx\n", info->page_offset); + get_page_offset_arm64(); return TRUE; } diff --git a/makedumpfile.c b/makedumpfile.c index b7c1c01251bf..ccf7eb4408ba 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -2291,6 +2291,7 @@ write_vmcoreinfo_data(void) WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR); #ifdef __aarch64__ + WRITE_NUMBER("MAX_USER_VA_BITS", MAX_USER_VA_BITS); WRITE_NUMBER("VA_BITS", VA_BITS); WRITE_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET); WRITE_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset); @@ -2694,6 +2695,7 @@ read_vmcoreinfo(void) READ_NUMBER("PAGE_BUDDY_MAPCOUNT_VALUE", PAGE_BUDDY_MAPCOUNT_VALUE); READ_NUMBER("phys_base", phys_base); #ifdef __aarch64__ + READ_NUMBER("MAX_USER_VA_BITS", MAX_USER_VA_BITS); READ_NUMBER("VA_BITS", VA_BITS); READ_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET); READ_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset); diff --git a/makedumpfile.h b/makedumpfile.h index d49f1f1fc1a9..3fa810e0bb40 100644 --- a/makedumpfile.h +++ b/makedumpfile.h @@ -1933,6 +1933,7 @@ struct number_table { long HUGETLB_PAGE_DTOR; long phys_base; #ifdef __aarch64__ + long MAX_USER_VA_BITS; long VA_BITS; unsigned long PHYS_OFFSET; unsigned long kimage_voffset; -- 2.7.4 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
