makedumpfile commit 94c97db3fe859ca14d7b38b0ae9ee0ffb83689d2 (arm64: Get 'info->page_offset' from PT_LOAD segments to support KASLR boot cases) added a method to determine 'info->page_offset' from PT_LOAD segments for arm64 platforms.
In this commit, I hardcoded the 'NOT_PADDR_ARM64' macro as 0x0000000010a80000UL which was a valid value on qualcomm-amberwing boards (which was the arm64 board available with me at the time). However, I was testing this change on several other arm64 boards like apm-mustang, huawei-taishan and hp-moonshot (now that I have access to them) and saw that this value can vary on the basis of the "Kernel code" memory range placement. To fix the same, this patchset uses a new approach. Since kernel version 4.19-rc5 (commit 23c85094fe1895caefdd19ef624ee687ec5f4507 ["proc/kcore: add vmcoreinfo note to /proc/kcore"]), '/proc/kcore' contains a new PT_NOTE which carries the VMCOREINFO information. If the same is available, we can use it for makedumpfile 'show_mem_usage()' functionality. This is especially useful for architectures like arm64 as we can get kernel symbols like 'VA_BITS' and 'kimage_voffset' from the '/proc/kcore' itself and use it to calculate 'info->page_offset' when we make a call to 'get_page_offset()'. This VMCOREINFO note provides us a standard interface which can be leveraged while debugging live (or primary) kernel with makedumpfile (and other user-space tools), especially to derive the machine specific details (for e.g. VA_BITS, PHYS_OFFSET and kimage_voffset for arm64 arch). The same has been suggested by the arm64 kernel maintainers (see [0]) as the standard interface exposed by kernel for sharing machine specific details with the user-land via vmcoreinfo. [0]. https://www.mail-archive.com/kexec@lists.infradead.org/msg20300.html I will send a follow-up patch to read 'kaslr_offset' for arm64 cases from vmcoreinfo inside '/proc/kcore' after this patchset is applied. Here are some details of the tests I ran: Testing: -------- 1. arm64 boards tested: huawei-taishan, apm-mustang and qualcomm-amberwing boards. 2. Use-cases tested: a) Primary kernel -> [] --mem-usage: # makedumpfile -f --mem-usage /proc/kcore [] filtering use-case: # makedumpfile --split -d 31 -x vmlinux --config scrub.conf vmcore dumpfile_{1,2,3} [] dumpfile creation: # makedumpfile -d 31 -x vmlinux vmcore dumpfile b) Crash kernel -> [] dumpfile creation: # makedumpfile -l --message-level 31 -d 31 /proc/vmcore dump 3. Kernel versions tested: a) Kernel version 4.19-rc5 and above. b) Kernel version 4.14. Fixes: 94c97db3fe859ca14d7b38b0ae9ee0ffb83689d2 "arm64: Get 'info->page_offset' from PT_LOAD segments to support KASLR boot cases" Cc: Baoquan He <b...@redhat.com> Cc: Kazuhito Hagio <k-ha...@ab.jp.nec.com> Signed-off-by: Bhupesh Sharma <bhsha...@redhat.com> --- arch/arm64.c | 114 +++++++++++++++++++++++++++++++++++++++++++-------------- makedumpfile.c | 67 ++++++++++++++++++++++++++++++--- makedumpfile.h | 2 +- 3 files changed, 149 insertions(+), 34 deletions(-) diff --git a/arch/arm64.c b/arch/arm64.c index 362609668ea2..d695eff628f0 100644 --- a/arch/arm64.c +++ b/arch/arm64.c @@ -53,6 +53,7 @@ static unsigned long kimage_voffset; #define PAGE_OFFSET_42 ((0xffffffffffffffffUL) << 42) #define PAGE_OFFSET_47 ((0xffffffffffffffffUL) << 47) #define PAGE_OFFSET_48 ((0xffffffffffffffffUL) << 48) +#define __PAGE_OFFSET(x) ((0xffffffffffffffffUL) << (x - 1)) #define pgd_val(x) ((x).pgd) #define pud_val(x) (pgd_val((x).pgd)) @@ -311,45 +312,104 @@ get_versiondep_info_arm64(void) unsigned long long virt_start; ulong _stext; - _stext = get_stext_symbol(); - if (!_stext) { - ERRMSG("Can't get the symbol of _stext.\n"); - return FALSE; - } + /* Calculate 'VA_BITS'. */ - /* 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; + /* Since kernel version 4.19, '/proc/kcore' contains a new + * PT_NOTE which carries the VMCOREINFO information. + * + * If the same is available, use it as it already contains the + * value of 'VA_BITS' on the machine. + * + * Otherwise, we can read the '_stext' symbol and determine the + * 'VA_BITS' value from the same as well. + */ + if (info->flag_kcore_contains_vmcoreinfo && + (NUMBER(VA_BITS) != NOT_FOUND_NUMBER)) { + va_bits = NUMBER(VA_BITS); } else { - ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n"); - return FALSE; + _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; + } + } + + /* Calculate 'info->page_offset'. */ + + /* Since kernel version 4.19, '/proc/kcore' contains a new + * PT_NOTE which carries the VMCOREINFO information. + * + * If the same is available, use it as it already contains the + * value of 'kimage_voffset' on the machine. + */ + if (info->flag_kcore_contains_vmcoreinfo && + (NUMBER(kimage_voffset) != NOT_FOUND_NUMBER)) { + kimage_voffset = NUMBER(kimage_voffset); } + /* First, lets try and calculate the 'info->page_offset' value + * from PT_LOAD segments, if they are available. + */ if (get_num_pt_loads()) { for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) { - if (virt_start != NOT_KV_ADDR - && virt_start < __START_KERNEL_map - && phys_start != NOT_PADDR - && phys_start != NOT_PADDR_ARM64) { - info->page_offset = virt_start - phys_start; - DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n", - info->page_offset, va_bits); - return TRUE; + /* On systems where we have a valid 'kimage_voffset' + * available by now, we should give preference to the same + * while calculating 'info->page_offset'. + * + * Otherwise, we can ensure that we consider + * only those PT_LOAD segments whose 'virt_start' + * is greater than the PAGE_OFFSET value (as defined + * in 'arch/arm64/include/asm/memory.h'). + */ + if (!kimage_voffset) { + if (virt_start != NOT_KV_ADDR && + virt_start > __PAGE_OFFSET(va_bits) && + phys_start != NOT_PADDR) { + info->page_offset = virt_start - phys_start; + DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n", + info->page_offset, va_bits); + return TRUE; + } + } else { + if (virt_start != NOT_KV_ADDR && + phys_start != NOT_PADDR && + (virt_start - phys_start) != kimage_voffset) { + info->page_offset = virt_start - phys_start; + DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n", + info->page_offset, va_bits); + return TRUE; + } } } } - info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1); + /* Fallback to hard-coded value (equal to PAGE_OFFSET macro + * defined in 'arch/arm64/include/asm/memory.h'), as the last + * resort. + * + * Note that this will not be a valid value on KASLR enabled + * kernels as the start address of linear range is also + * randomized for KASLR boot cases. + */ + info->page_offset = __PAGE_OFFSET(va_bits); DEBUG_MSG("page_offset=%lx, va_bits=%d\n", info->page_offset, va_bits); diff --git a/makedumpfile.c b/makedumpfile.c index 91c1ab47fca4..a1b8d8ff5a84 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -1302,6 +1302,20 @@ error: return FALSE; } +static int +check_kcore_contains_vmcoreinfo(int fd, char *name) +{ + if (!get_elf_info(fd, name)) + return FALSE; + + if (!has_vmcoreinfo()) + return FALSE; + + DEBUG_MSG("VMCOREINFO PT_NOTE found in %s\n", name); + + return TRUE; +} + int open_dump_memory(void) { @@ -1314,6 +1328,23 @@ open_dump_memory(void) } info->fd_memory = fd; + /* Since kernel version 4.19, '/proc/kcore' contains a new + * PT_NOTE which carries the VMCOREINFO information. + * + * If the same is available, use it for makedumpfile + * show_mem_usage() cases. + */ + if (info->flag_mem_usage && + !(strcmp(info->name_memory, "/proc/kcore")) && + (info->kernel_version >= KERNEL_VERSION(4, 19, 0))){ + status = check_kcore_contains_vmcoreinfo(fd, + info->name_memory); + if (status == TRUE) { + info->flag_kcore_contains_vmcoreinfo = TRUE; + return TRUE; + } + } + status = check_kdump_compressed(info->name_memory); if (status == TRUE) { info->flag_refiltering = TRUE; @@ -11195,6 +11226,8 @@ static int get_sys_kernel_vmcoreinfo(uint64_t *addr, uint64_t *len) int show_mem_usage(void) { + off_t offset; + unsigned long size; uint64_t vmcoreinfo_addr, vmcoreinfo_len; struct cycle cycle = {0}; @@ -11208,17 +11241,39 @@ int show_mem_usage(void) if (!open_files_for_creating_dumpfile()) return FALSE; - if (!get_elf_loads(info->fd_memory, info->name_memory)) - return FALSE; + /* Since kernel version 4.19, '/proc/kcore' contains a new + * PT_NOTE which carries the VMCOREINFO information. + * + * If the same is available, use it for makedumpfile + * show_mem_usage(). This is especially useful for architectures + * like arm64 as we can get symbols like 'VA_BITS' and + * 'kimage_voffset' before we call get_page_offset(). + */ + + if (!info->flag_kcore_contains_vmcoreinfo) { + if (!get_elf_loads(info->fd_memory, info->name_memory)) + return FALSE; + } else { + if (has_vmcoreinfo()) { + get_vmcoreinfo(&offset, &size); + if (!read_vmcoreinfo_from_vmcore(offset, size, FALSE)) + return FALSE; + } + } if (!get_page_offset()) return FALSE; - if (!get_sys_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len)) - return FALSE; + /* If flag_kcore_contains_vmcoreinfo is TRUE when we are here, + * we don't need to read the vmcoreinfo again. + */ + if (!info->flag_kcore_contains_vmcoreinfo) + if (!get_sys_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len)) + return FALSE; - if (!set_kcore_vmcoreinfo(vmcoreinfo_addr, vmcoreinfo_len)) - return FALSE; + if (!info->flag_kcore_contains_vmcoreinfo) + if (!set_kcore_vmcoreinfo(vmcoreinfo_addr, vmcoreinfo_len)) + return FALSE; if (!initial()) return FALSE; diff --git a/makedumpfile.h b/makedumpfile.h index 46ebe2ee5a1f..77f7ec8e3867 100644 --- a/makedumpfile.h +++ b/makedumpfile.h @@ -544,7 +544,6 @@ unsigned long get_kvbase_arm64(void); #define KVBASE get_kvbase_arm64() #define __START_KERNEL_map (0xffffffff80000000UL) -#define NOT_PADDR_ARM64 (0x0000000010a80000UL) #endif /* aarch64 */ @@ -1308,6 +1307,7 @@ struct DumpInfo { int flag_vmemmap; /* kernel supports vmemmap address space */ int flag_excludevm; /* -e - excluding unused vmemmap pages */ int flag_use_count; /* _refcount is named _count in struct page */ + int flag_kcore_contains_vmcoreinfo; /* '/proc/kcore' contains a VMCOREINFO PT_NOTE */ unsigned long vaddr_for_vtop; /* virtual address for debugging */ long page_size; /* size of page */ long page_shift; -- 2.7.4 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
