[Crash-utility] add support for incomplete elf dump file

Since the incomplete dump file generated by ENOSPC error can't be analysed by crash utility, but sometimes this file may contain important information and the panic problem won't be reproduced, then we came up with an idea to modify the exist data of the incomplete dump file to make it analysable by crash utility. However, we found it will be more suitable to check the incomplete data than modifying it in make dump file. So, we change the p_filesz of PT_LOAD header, zero_fill and phys_end of PT_LOAD segments, to make crash can analyse incomplete ELF dump file, when incomplete flag exists. the issue was discussed at http://lists.infradead.org/pipermail/kexec/2014-October/012669.html --- a/netdump.c +++ b/netdump.c @@ -52,6 +52,7 @@ static char *vmcoreinfo_read_string(const char *); #define MIN_PAGE_SIZE (4096) +#define DUMP_ELF_INCOMPLETE 0x1 /* * Architectures that have configurable page sizes, * can differ from the host machine's page size. @@ -488,6 +489,10 @@ check_dumpfile_size(char *file) if (stat64(file, &stat) < 0) return; + Elf64_Phdr *load64 = nd->load64; + Elf32_Phdr *load32 = nd->load32; + unsigned int e_flag = (NULL == nd->elf64) ? (nd->elf32)->e_flags : (nd->elf64)->e_flags; + int status = e_flag & DUMP_ELF_INCOMPLETE; for (i = 0; i < nd->num_pt_load_segments; i++) { pls = &nd->pt_load_segments[i]; @@ -495,7 +500,19 @@ check_dumpfile_size(char *file) (pls->phys_end - pls->phys_start); if (segment_end > stat.st_size) { - error(WARNING, "%s: may be truncated or incomplete\n" + if (!status){ + error(WARNING, "%s: may be truncated\n" + " PT_LOAD p_offset: %lld\n" + " p_filesz: %lld\n" + " bytes required: %lld\n" + " dumpfile size: %lld\n\n", + file, pls->file_offset, + pls->phys_end - pls->phys_start, + segment_end, stat.st_size); + return; + } + else{ + error(WARNING, "%s: may be incomplete\n" " PT_LOAD p_offset: %lld\n" " p_filesz: %lld\n" " bytes required: %lld\n" @@ -503,8 +520,25 @@ check_dumpfile_size(char *file) file, pls->file_offset, pls->phys_end - pls->phys_start, segment_end, stat.st_size); - return; + } + if (pls->file_offset > stat.st_size){ + pls->file_offset = 0; + pls->phys_start = 0; + pls->phys_end = 0; + } + else { + if (NULL == load32) + load64->p_filesz = stat.st_size - pls->file_offset; + else + load32->p_filesz = stat.st_size - pls->file_offset; + pls->zero_fill = pls->phys_end; + pls->phys_end = stat.st_size - pls->file_offset + pls->phys_start; + } } + if (NULL == load32) + load64++; + else + load32++; } }