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13e165baf6
One of our users reported that when a user-level program SIGSEGVs under
UML kernel, the resulting core dump is not very usable.
I have reproduced that with the latest kernel:
make ARCH=um defconfig; make ARCH=um
Run the resulting kernel, then "inside" run this program:
#include <pthread.h>
void *fn(void *p)
{
abort();
}
int main()
{
pthread_t tid;
pthread_create(&tid, 0, fn, 0);
pthread_join(tid, 0);
return 0;
}
Analyze the coredump with GDB. Here is what you'll see:
sudo gdb -q -ex 'set solib-absolute-prefix ../root_fs' -ex 'file ../root_fs/var/tmp/mt-abort' -ex 'core ../root_fs/var/tmp/core.762'
Reading symbols from /usr/local/google/root_fs/var/tmp/mt-abort...done.
[New Thread 763]
[New Thread 762]
Core was generated by `./mt-abort'.
Program terminated with signal 6, Aborted.
#0 0x0000000040255250 in raise () from ../root_fs/lib64/libc.so.6
(gdb) info thread
2 Thread 762 0x0000000000000000 in ?? ()
* 1 Thread 763 0x0000000040255250 in raise () from ../root_fs/lib64/libc.so.6
Note that thread#2 looks funny.
(gdb) thread 2
[Switching to thread 2 (Thread 762)]#0 0x0000000000000000 in ?? ()
(gdb) info reg
rax 0x0 0
rbx 0x0 0
rcx 0x0 0
rdx 0x0 0
rsi 0x0 0
rdi 0x0 0
rbp 0x0 0x0
rsp 0x0 0x0
r8 0x0 0
r9 0x0 0
r10 0x0 0
r11 0x0 0
r12 0x0 0
r13 0x0 0
r14 0x0 0
r15 0x0 0
rip 0x0 0
eflags 0x0 [ ]
cs 0x0 0
ss 0x0 0
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
Examining the core shows that NT_PRSTATUS notes for all threads other than
the one that crashed are zeroed out.
I believe this is happening because neither ELF_CORE_COPY_TASK_REGS nor
task_pt_regs are defined under ARCH=um, and so elf_core_copy_task_regs()
becomes a no-op.
Attached patch fixes this for SUBARCH={x86_64,i386}.
Signed-off-by: Paul Pluzhnikov <ppluzhnikov@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
123 lines
3.6 KiB
C
123 lines
3.6 KiB
C
/*
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* Copyright 2003 PathScale, Inc.
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* Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*
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* Licensed under the GPL
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*/
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#ifndef __UM_ELF_X86_64_H
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#define __UM_ELF_X86_64_H
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#include <asm/user.h>
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#include "skas.h"
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/* x86-64 relocation types, taken from asm-x86_64/elf.h */
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#define R_X86_64_NONE 0 /* No reloc */
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#define R_X86_64_64 1 /* Direct 64 bit */
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#define R_X86_64_PC32 2 /* PC relative 32 bit signed */
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#define R_X86_64_GOT32 3 /* 32 bit GOT entry */
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#define R_X86_64_PLT32 4 /* 32 bit PLT address */
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#define R_X86_64_COPY 5 /* Copy symbol at runtime */
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#define R_X86_64_GLOB_DAT 6 /* Create GOT entry */
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#define R_X86_64_JUMP_SLOT 7 /* Create PLT entry */
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#define R_X86_64_RELATIVE 8 /* Adjust by program base */
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#define R_X86_64_GOTPCREL 9 /* 32 bit signed pc relative
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offset to GOT */
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#define R_X86_64_32 10 /* Direct 32 bit zero extended */
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#define R_X86_64_32S 11 /* Direct 32 bit sign extended */
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#define R_X86_64_16 12 /* Direct 16 bit zero extended */
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#define R_X86_64_PC16 13 /* 16 bit sign extended pc relative */
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#define R_X86_64_8 14 /* Direct 8 bit sign extended */
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#define R_X86_64_PC8 15 /* 8 bit sign extended pc relative */
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#define R_X86_64_NUM 16
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typedef unsigned long elf_greg_t;
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#define ELF_NGREG (sizeof (struct user_regs_struct) / sizeof(elf_greg_t))
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typedef elf_greg_t elf_gregset_t[ELF_NGREG];
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typedef struct user_i387_struct elf_fpregset_t;
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/*
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* This is used to ensure we don't load something for the wrong architecture.
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*/
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#define elf_check_arch(x) \
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((x)->e_machine == EM_X86_64)
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#define ELF_CLASS ELFCLASS64
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#define ELF_DATA ELFDATA2LSB
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#define ELF_ARCH EM_X86_64
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#define ELF_PLAT_INIT(regs, load_addr) do { \
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PT_REGS_RBX(regs) = 0; \
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PT_REGS_RCX(regs) = 0; \
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PT_REGS_RDX(regs) = 0; \
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PT_REGS_RSI(regs) = 0; \
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PT_REGS_RDI(regs) = 0; \
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PT_REGS_RBP(regs) = 0; \
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PT_REGS_RAX(regs) = 0; \
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PT_REGS_R8(regs) = 0; \
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PT_REGS_R9(regs) = 0; \
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PT_REGS_R10(regs) = 0; \
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PT_REGS_R11(regs) = 0; \
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PT_REGS_R12(regs) = 0; \
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PT_REGS_R13(regs) = 0; \
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PT_REGS_R14(regs) = 0; \
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PT_REGS_R15(regs) = 0; \
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} while (0)
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#define ELF_CORE_COPY_REGS(pr_reg, _regs) \
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(pr_reg)[0] = (_regs)->regs.gp[0]; \
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(pr_reg)[1] = (_regs)->regs.gp[1]; \
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(pr_reg)[2] = (_regs)->regs.gp[2]; \
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(pr_reg)[3] = (_regs)->regs.gp[3]; \
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(pr_reg)[4] = (_regs)->regs.gp[4]; \
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(pr_reg)[5] = (_regs)->regs.gp[5]; \
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(pr_reg)[6] = (_regs)->regs.gp[6]; \
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(pr_reg)[7] = (_regs)->regs.gp[7]; \
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(pr_reg)[8] = (_regs)->regs.gp[8]; \
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(pr_reg)[9] = (_regs)->regs.gp[9]; \
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(pr_reg)[10] = (_regs)->regs.gp[10]; \
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(pr_reg)[11] = (_regs)->regs.gp[11]; \
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(pr_reg)[12] = (_regs)->regs.gp[12]; \
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(pr_reg)[13] = (_regs)->regs.gp[13]; \
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(pr_reg)[14] = (_regs)->regs.gp[14]; \
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(pr_reg)[15] = (_regs)->regs.gp[15]; \
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(pr_reg)[16] = (_regs)->regs.gp[16]; \
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(pr_reg)[17] = (_regs)->regs.gp[17]; \
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(pr_reg)[18] = (_regs)->regs.gp[18]; \
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(pr_reg)[19] = (_regs)->regs.gp[19]; \
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(pr_reg)[20] = (_regs)->regs.gp[20]; \
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(pr_reg)[21] = current->thread.arch.fs; \
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(pr_reg)[22] = 0; \
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(pr_reg)[23] = 0; \
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(pr_reg)[24] = 0; \
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(pr_reg)[25] = 0; \
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(pr_reg)[26] = 0;
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#define task_pt_regs(t) (&(t)->thread.regs)
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struct task_struct;
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extern int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu);
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#define ELF_CORE_COPY_FPREGS(t, fpu) elf_core_copy_fpregs(t, fpu)
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#ifdef TIF_IA32 /* XXX */
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#error XXX, indeed
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clear_thread_flag(TIF_IA32);
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#endif
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#define ELF_EXEC_PAGESIZE 4096
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#define ELF_ET_DYN_BASE (2 * TASK_SIZE / 3)
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extern long elf_aux_hwcap;
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#define ELF_HWCAP (elf_aux_hwcap)
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#define ELF_PLATFORM "x86_64"
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#define SET_PERSONALITY(ex) do ; while(0)
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#endif
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