From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262052AbUKDCC3 (ORCPT ); Wed, 3 Nov 2004 21:02:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262049AbUKDCBv (ORCPT ); Wed, 3 Nov 2004 21:01:51 -0500 Received: from host157-148.pool8289.interbusiness.it ([82.89.148.157]:64659 "EHLO zion.localdomain") by vger.kernel.org with ESMTP id S262052AbUKDBzi (ORCPT ); Wed, 3 Nov 2004 20:55:38 -0500 Subject: [patch 14/20] uml: fix sysemu test at startup To: akpm@osdl.org Cc: jdike@addtoit.com, linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, cw@f00f.org, blaisorblade_spam@yahoo.it, bodo.stroesser@fujitsu-siemens.com From: blaisorblade_spam@yahoo.it Date: Thu, 04 Nov 2004 00:17:47 +0100 Message-Id: <20041103231747.7CCC855C83@zion.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo 'Blaisorblade' Giarrusso , Bodo Stroesser , Jeff Dike Currently, the test for the SYSEMU support on the host is completely wrong, as Bodo noticed. We should change the syscall result (inserting the host pid) and check if it is received correctly by the guest. What we actually do, without this patch, is to overwrite the syscall number. This went unnoticed because we only check that the getpid() syscall from the child does not return its pid. We don't check that it returns the correct value. Also, override the result portably, using the PT_SYSCALL_RET_OFFSET macro which abstract away the host stack frame layout (took from Jeff Dike code). Signed-off-by: Paolo 'Blaisorblade' Giarrusso --- vanilla-linux-2.6.9-paolo/arch/um/kernel/process.c | 16 ++++++---------- 1 files changed, 6 insertions(+), 10 deletions(-) diff -puN arch/um/kernel/process.c~uml-fix-sysemu-test-startup arch/um/kernel/process.c --- vanilla-linux-2.6.9/arch/um/kernel/process.c~uml-fix-sysemu-test-startup 2004-11-03 23:45:15.751044208 +0100 +++ vanilla-linux-2.6.9-paolo/arch/um/kernel/process.c 2004-11-03 23:45:15.754043752 +0100 @@ -214,8 +214,6 @@ static void __init check_sysemu(void) sysemu_supported = 0; pid = start_ptraced_child(&stack); if(ptrace(PTRACE_SYSEMU, pid, 0, 0) >= 0) { - struct user_regs_struct regs; - CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); if (n < 0) panic("check_ptrace : wait failed, errno = %d", errno); @@ -223,18 +221,16 @@ static void __init check_sysemu(void) panic("check_ptrace : expected SIGTRAP, " "got status = %d", status); - if (ptrace(PTRACE_GETREGS, pid, 0, ®s) < 0) - panic("check_ptrace : failed to read child " - "registers, errno = %d", errno); - regs.orig_eax = pid; - if (ptrace(PTRACE_SETREGS, pid, 0, ®s) < 0) - panic("check_ptrace : failed to modify child " - "registers, errno = %d", errno); + n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, + os_getpid()); + if(n < 0) + panic("check_ptrace : failed to modify system " + "call return, errno = %d", errno); stop_ptraced_child(pid, stack, 0); sysemu_supported = 1; - printk("found\n"); + printk("OK\n"); } else { _