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  1. 06 Jul, 2007 2 commits
    • Jason Wessel's avatar
      i386: fix regression, endless loop in ptrace singlestep over an int80 · 1e2e99f0
      Jason Wessel authored 
      The commit 635cf99a introduced a
regression.  Executing a ptrace single step after certain int80
accesses will infinitely loop and never advance the PC.

The TIF_SINGLESTEP check should be done on the return from the syscall
and not before it.

I loops on each single step on the pop right after the int80 which writes out
to the console.  At that point you can issue as many single steps as you want
and it will not advance any further.

The test case is below:

/* Test whether singlestep through an int80 syscall works.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <asm/user.h>
#include <string.h>

static int child, status;
static struct user_regs_struct regs;

static void do_child()
{
	char str[80] = "child: int80 test\n";

	ptrace(PTRACE_TRACEME, 0, 0, 0);
	kill(getpid(), SIGUSR1);
	write(fileno(stdout),str,strlen(str));
	asm ("int $0x80" : : "a" (20)); /* getpid */
}

static void do_parent()
{
	unsigned long eip, expected = 0;
again:
	waitpid(child, &status, 0);
	if (WIFEXITED(status) || WIFSIGNALED(status))
		return;

	if (WIFSTOPPED(status)) {
		ptrace(PTRACE_GETREGS, child, 0, &regs);
		eip = regs.eip;
		if (expected)
			fprintf(stderr, "child stop @ %08lx, expected %08lx %s\n",
					eip, expected,
					eip == expected ? "" : " <== ERROR");

		if (*(unsigned short *)eip == 0x80cd) {
			fprintf(stderr, "int 0x80 at %08x\n", (unsigned int)eip);
			expected = eip + 2;
		} else
			expected = 0;

		ptrace(PTRACE_SINGLESTEP, child, NULL, NULL);
	}
	goto again;
}

int main(int argc, char * const argv[])
{
	child = fork();
	if (child)
		do_parent();
	else
		do_child();
	return 0;
}
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: <stable@kernel.org>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1e2e99f0
    • Michael Ellerman's avatar
      Fix elf_core_dump() when writing arch specific notes (spu coredumps) · ef7320ed
      Michael Ellerman authored 
      elf_core_dump() supports dumping arch specific ELF notes, via the #define
ELF_CORE_WRITE_EXTRA_NOTES.  Currently the only user of this is the powerpc
spu coredump code.

There is a bug in the handling of foffset WRT the arch notes, which causes
us to erroneously increment foffset by the size of the arch notes, leaving
a block of zeroes in the file, and causing all subsequent data in the file
to be at <supposed position> + <arch note size>.  eg:

  LOAD  0x050000 0x00100000 0x00000000 0x20000 0x20000 R E 0x10000

Tells us we should have a chunk of data at 0x50000.  The truth is the data
is at 0x90dbc = 0x50000 + 0x40dbc (the size of the arch notes).

This bug prevents gdb from reading the core file correctly.

The simplest fix is to simply remember the size of the arch notes, and add
it to foffset after we've written the arch notes.  The only drawback is
that if the arch code doesn't write as many bytes as it said it would, we
end up with a broken core dump again.  For now I think that's a reasonable
requirement.

Tested on a Cell blade, gdb no longer complains about the core file being
bogus.

While I'm here I should point out that the spu coredump code does not work
if we're dumping to a pipe - we'll have to wait for 23 to fix that.
Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ef7320ed
  3. 05 Jul, 2007 5 commits
  5. 04 Jul, 2007 12 commits
  7. 03 Jul, 2007 21 commits
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