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/52-bit virtual addressing. Since at the moment we enable the support of this extension in the kernel via a CONFIG flag (CONFIG_ARM64_VA_BITS_52), so there are no clear mechanisms in user-space to determine this CONFIG flag value and use it to determine the kernel-space VA address range values. 'makedumpfile' can instead use 'TCR_EL1.T1SZ' value from vmcoreinfo which indicates the size offset of the memory region addressed by TTBR1_EL1 (and hence can be used for determining the vabits_actual value). The user-space computation for determining whether an address lies in the linear map range is the same as we have in kernel-space: #define __is_lm_address(addr) (!(((u64)addr) & BIT(vabits_actual - 1))) I have sent a kernel patch upstream to add 'TCR_EL1.T1SZ' to vmcoreinfo for arm64 (see [0]). This patch is in accordance with ARMv8 Architecture Reference Manual version D.a Note that with these changes the '--mem-usage' option will not work properly for arm64 (a subsequent patch in this series will address the same) and there is a discussion on-going with the arm64 maintainers to find a way-out for the same (via standard kernel symbols like _stext). [0].http://lists.infradead.org/pipermail/kexec/2019-November/023962.html Cc: Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx> Cc: John Donnelly <john.p.donnelly@xxxxxxxxxx> Cc: kexec@xxxxxxxxxxxxxxxxxxx Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx> --- arch/arm64.c | 148 +++++++++++++++++++++++++++++++++++++++++++++------------ makedumpfile.c | 2 + makedumpfile.h | 3 +- 3 files changed, 122 insertions(+), 31 deletions(-) diff --git a/arch/arm64.c b/arch/arm64.c index ecb19139e178..094d73b8a60f 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 vabits_actual; static unsigned long kimage_voffset; #define SZ_4K 4096 @@ -218,12 +219,19 @@ pmd_page_paddr(pmd_t pmd) #define pte_index(vaddr) (((vaddr) >> PAGESHIFT()) & (PTRS_PER_PTE - 1)) #define pte_offset(dir, vaddr) (pmd_page_paddr((*dir)) + pte_index(vaddr) * sizeof(pte_t)) +/* + * The linear kernel range starts at the bottom of the virtual address + * space. Testing the top bit for the start of the region is a + * sufficient check and avoids having to worry about the tag. + */ +#define is_linear_addr(addr) (!(((unsigned long)addr) & (1UL << (vabits_actual - 1)))) + static unsigned long long __pa(unsigned long vaddr) { if (kimage_voffset == NOT_FOUND_NUMBER || - (vaddr >= PAGE_OFFSET)) - return (vaddr - PAGE_OFFSET + info->phys_base); + is_linear_addr(vaddr)) + return (vaddr + info->phys_base - PAGE_OFFSET); else return (vaddr - kimage_voffset); } @@ -253,6 +261,7 @@ static int calculate_plat_config(void) (PAGESIZE() == SZ_64K && va_bits == 42)) { pgtable_level = 2; } else if ((PAGESIZE() == SZ_64K && va_bits == 48) || + (PAGESIZE() == SZ_64K && va_bits == 52) || (PAGESIZE() == SZ_4K && va_bits == 39) || (PAGESIZE() == SZ_16K && va_bits == 47)) { pgtable_level = 3; @@ -287,6 +296,16 @@ get_phys_base_arm64(void) return TRUE; } + /* If both vabits_actual and va_bits are now initialized, always + * prefer vabits_actual over va_bits to calculate PAGE_OFFSET + * value. + */ + if (vabits_actual && va_bits && vabits_actual != va_bits) { + info->page_offset = (-(1UL << vabits_actual)); + DEBUG_MSG("page_offset : %lx (via vabits_actual)\n", + info->page_offset); + } + if (get_num_pt_loads() && PAGE_OFFSET) { for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); @@ -406,6 +425,73 @@ 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. Note that this is a + * best case approximation at the moment, as there can be + * inconsistencies in this calculation (for e.g., for + * 52-bit kernel VA case, even the 48th bit might be set in + * the _stext symbol). + * + * So, we need to rely on the actual VA_BITS symbol in the + * vmcoreinfo for a accurate value. + * + * TODO: Improve this further once there is a closure with arm64 + * kernel maintainers on the same. + */ + if ((_stext & PAGE_OFFSET_52) == PAGE_OFFSET_52) { + va_bits = 52; + } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) { + va_bits = 48; + } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) { + va_bits = 47; + } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) { + va_bits = 42; + } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) { + va_bits = 39; + } else if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) { + va_bits = 36; + } else { + ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); + return FALSE; + } + + DEBUG_MSG("va_bits : %d (_stext) (approximation)\n", va_bits); + + return TRUE; +} + +static void +get_page_offset_arm64(void) +{ + /* Check if 'vabits_actual' is initialized yet. + * If not, our best bet is to use 'va_bits' to calculate + * the PAGE_OFFSET value, otherwise use 'vabits_actual' + * for the same. + * + * See arch/arm64/include/asm/memory.h for more details. + */ + if (!vabits_actual) { + info->page_offset = (-(1UL << va_bits)); + DEBUG_MSG("page_offset : %lx (approximation)\n", + info->page_offset); + } else { + info->page_offset = (-(1UL << vabits_actual)); + DEBUG_MSG("page_offset : %lx (accurate)\n", + info->page_offset); + } + +} + int get_machdep_info_arm64(void) { @@ -420,8 +506,33 @@ 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() == FALSE) + return FALSE; + + get_page_offset_arm64(); + + /* See TCR_EL1, Translation Control Register (EL1) register + * description in the ARMv8 Architecture Reference Manual. + * Basically, we can use the TCR_EL1.T1SZ + * value to determine the virtual addressing range supported + * in the kernel-space (i.e. vabits_actual). + */ + if (NUMBER(tcr_el1_t1sz) != NOT_FOUND_NUMBER) { + vabits_actual = 64 - NUMBER(tcr_el1_t1sz); + DEBUG_MSG("vabits_actual : %d (vmcoreinfo)\n", + vabits_actual); + } if (!calculate_plat_config()) { ERRMSG("Can't determine platform config values\n"); @@ -459,34 +570,11 @@ 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() == FALSE) + return FALSE; - 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 4a000112ba59..baf559e4d74e 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -2314,6 +2314,7 @@ write_vmcoreinfo_data(void) WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR); #ifdef __aarch64__ WRITE_NUMBER("VA_BITS", VA_BITS); + WRITE_NUMBER_UNSIGNED("tcr_el1_t1sz", tcr_el1_t1sz); WRITE_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET); WRITE_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset); #endif @@ -2720,6 +2721,7 @@ read_vmcoreinfo(void) READ_NUMBER("KERNEL_IMAGE_SIZE", KERNEL_IMAGE_SIZE); #ifdef __aarch64__ READ_NUMBER("VA_BITS", VA_BITS); + READ_NUMBER_UNSIGNED("tcr_el1_t1sz", tcr_el1_t1sz); READ_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET); READ_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset); #endif diff --git a/makedumpfile.h b/makedumpfile.h index ac11e906b5b7..7eab6507c8df 100644 --- a/makedumpfile.h +++ b/makedumpfile.h @@ -974,7 +974,7 @@ int get_versiondep_info_arm64(void); int get_xen_basic_info_arm64(void); int get_xen_info_arm64(void); unsigned long get_kaslr_offset_arm64(unsigned long vaddr); -#define paddr_to_vaddr_arm64(X) (((X) - info->phys_base) | PAGE_OFFSET) +#define paddr_to_vaddr_arm64(X) (((X) - (info->phys_base - PAGE_OFFSET))) #define find_vmemmap() stub_false() #define vaddr_to_paddr(X) vaddr_to_paddr_arm64(X) @@ -1937,6 +1937,7 @@ struct number_table { long KERNEL_IMAGE_SIZE; #ifdef __aarch64__ long VA_BITS; + unsigned long tcr_el1_t1sz; unsigned long PHYS_OFFSET; unsigned long kimage_voffset; #endif -- 2.7.4 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
