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Commit f1ef9167 authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
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uml: work around broken host PTRACE_SYSEMU 



Fedora broke PTRACE_SYSEMU again, and UML crashes as a result when it
doesn't need to.  This patch makes the PTRACE_SYSEMU check fail gracefully
and makes UML fall back to PTRACE_SYSCALL.

Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 14c8a77e

arch/um/os-Linux/start_up.c

+16 −9
Original line number Diff line number Diff line
@@ -121,8 +121,10 @@ static int stop_ptraced_child(int pid, int exitcode, int mustexit) 
{

	int status, n, ret = 0;



	if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)

		fatal_perror("stop_ptraced_child : ptrace failed");

	if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {

		perror("stop_ptraced_child : ptrace failed");

		return -1;

	}

	CATCH_EINTR(n = waitpid(pid, &status, 0));

	if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {

		int exit_with = WEXITSTATUS(status);
@@ -212,7 +214,7 @@ static void __init check_sysemu(void) 
	if (n < 0)

		fatal_perror("check_sysemu : wait failed");

	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))

		fatal("check_sysemu : expected SIGTRAP, got status = %d",

		fatal("check_sysemu : expected SIGTRAP, got status = %d\n",

		      status);



	if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
@@ -254,9 +256,11 @@ static void __init check_sysemu(void) 


		if (WIFSTOPPED(status) &&

		    (WSTOPSIG(status) == (SIGTRAP|0x80))) {

			if (!count)

				fatal("check_ptrace : SYSEMU_SINGLESTEP "

			if (!count) {

				non_fatal("check_ptrace : SYSEMU_SINGLESTEP "

					  "doesn't singlestep");

				goto fail;

			}

			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,

				   os_getpid());

			if (n < 0)
@@ -266,9 +270,12 @@ static void __init check_sysemu(void) 
		}

		else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))

			count++;

		else

			fatal("check_ptrace : expected SIGTRAP or "

			      "(SIGTRAP | 0x80), got status = %d", status);

		else {

			non_fatal("check_ptrace : expected SIGTRAP or "

				  "(SIGTRAP | 0x80), got status = %d\n",

				  status);

			goto fail;

		}

	}

	if (stop_ptraced_child(pid, 0, 0) < 0)

		goto fail_stopped;