[Crash-utility] Re: [PATCH v3] ppc64: Fix bt printing error stack trace

> <...snip...> Regarding to v1's discussion, we cannot run abiv1 program on abiv2 kernel, it's because abiv1 is big-endian and abiv2 is little-endian, and abiv2, or ppc64le kernel doesn't support big-endian, or abiv1 program cannot run upon it, see the following: $ file blkid blkid: ELF 64-bit MSB executable, 64-bit PowerPC or cisco 7500, Power ELF V1 ABI, version 1 (GNU/Linux), statically linked, for GNU/Linux 3.2.0, BuildID[sha1]=b36e8a2a5e4d27039591a35fca38fa48735f5540, stripped $ ~/qemu-10.1.2/build/qemu-ppc64 ./blkid /dev/mapper/root: UUID="..." TYPE="xfs" /dev/sda3: UUID="..." TYPE="LVM2_member" PARTUUID="..." /dev/sda2: UUID="..." TYPE="xfs" PARTUUID="..." /dev/mapper/swap: UUID="..." TYPE="swap" /dev/mapper/home: UUID="..." TYPE="xfs" /dev/sda1: PARTUUID="..." $ ./blkid -bash: ./blkid: cannot execute binary file: Exec format error $ uname -a Linux 6.12.0-150.el10.ppc64le #1 SMP Fri Oct 31 06:58:14 EDT 2025 ppc64le GNU/Linux $ file /bin/bash /bin/bash: ELF 64-bit LSB pie executable, 64-bit PowerPC or cisco 7500, OpenPOWER ELF V2 ABI, version 1 (SYSV), dynamically linked, interpreter /lib64/ld64.so.2, BuildID[sha1]=9ab800028ced16c5974f5b19cb6ed754178802a8, for GNU/Linux 3.10.0, stripped The abiv1 program blkid cannot be run on this machine, except with the help of qemu. So from my view, we don't need to consider the case that abiv2 kernel might containing a abiv1 program or .ko. Please feel free to correct me if I'm wrong. @Aditya Gupta

--- defs.h | 3 ++- netdump.c | 14 ++++++++++---- ppc64.c | 34 +++++++++++++++++++++++++++++++--- symbols.c | 5 +++-- 4 files changed, 46 insertions(+), 10 deletions(-) diff --git a/defs.h b/defs.h index ab4aee8..19dff88 100644 --- a/defs.h +++ b/defs.h @@ -4699,6 +4699,7 @@ struct efi_memory_desc_t { #define MSR_PR_LG 14 /* Problem State / Privilege Level */ /* Used to find the user or kernel-mode frame*/ +#define STACK_SWITCH_FRAME_REGS 48 #define STACK_FRAME_OVERHEAD 112 #define EXCP_FRAME_MARKER 0x7265677368657265 > <...snip...> @@ -3035,6 +3036,25 @@ ppc64_get_sp(ulong task) return sp; } +static bool +is_ppc64_elf_abi_v2(void) +{ + static bool ret = false; + static bool checked = false; + + if (checked) + return ret; + switch (file_elf_header(pc->namelist, "e_flags")) { + case 2: + ret = true; + case 1: + break; + default: + error(WARNING, "Unknown e_flags for v1/v2 elf_abi detection.\n"); + } + checked = true; + return ret; +} /* * get the SP and PC values for idle tasks. @@ -3056,9 +3076,17 @@ get_ppc64_frame(struct bt_info *bt, ulong *getpc, ulong *getsp) sp = ppc64_get_sp(task); if (!INSTACK(sp, bt)) goto out; - readmem(sp+STACK_FRAME_OVERHEAD, KVADDR, &regs, - sizeof(struct ppc64_pt_regs), - "PPC64 pt_regs", FAULT_ON_ERROR); + + if (THIS_KERNEL_VERSION >= LINUX(6,2,0) && is_ppc64_elf_abi_v2()) {

+ readmem(sp+STACK_SWITCH_FRAME_REGS, KVADDR, &regs, + sizeof(struct ppc64_pt_regs), + "PPC64 pt_regs", FAULT_ON_ERROR); + } else { + readmem(sp+STACK_FRAME_OVERHEAD, KVADDR, &regs, + sizeof(struct ppc64_pt_regs), + "PPC64 pt_regs", FAULT_ON_ERROR); + } + ip = regs.nip; closest = closest_symbol(ip); if (STREQ(closest, ".__switch_to") || STREQ(closest, "__switch_to")) { diff --git a/symbols.c b/symbols.c index 480fdb6..0a11c2f 100644 --- a/symbols.c +++ b/symbols.c @@ -217,7 +217,7 @@ symtab_init(void) * Check whether the namelist is a kerntypes file built by * dwarfextract, which places a magic number in e_version. */ - if (file_elf_version(pc->namelist) == EV_DWARFEXTRACT) + if (file_elf_header(pc->namelist, "e_version") == EV_DWARFEXTRACT) pc->flags |= KERNTYPES; if (pc->flags & SYSMAP) { @@ -13149,7 +13149,8 @@ load_module_symbols(char *modref, char *namelist, ulong base_addr) error(FATAL, "cannot determine object file format: %s\n", namelist); - if (LKCD_KERNTYPES() && (file_elf_version(namelist) == EV_DWARFEXTRACT)) + if (LKCD_KERNTYPES() && + (file_elf_header(namelist, "e_version") == EV_DWARFEXTRACT)) goto add_symbols; /* no symbols, add the debuginfo */ if (!(bfd_get_file_flags(mbfd) & HAS_SYMS))