Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755907AbXIVPj5 (ORCPT ); Sat, 22 Sep 2007 11:39:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751860AbXIVPju (ORCPT ); Sat, 22 Sep 2007 11:39:50 -0400 Received: from rv-out-0910.google.com ([209.85.198.185]:38073 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751544AbXIVPjt (ORCPT ); Sat, 22 Sep 2007 11:39:49 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:date:from:to:cc:subject:message-id:mime-version:content-type:content-disposition:user-agent; b=eJZVh4WBk6v5RTlWVNXokPO/aLyZrHa19CzZxNBVkXnBGgslLhmIJ5AtPvCi/UZBX2AX0fSAREn8+6V8hgUbi3Y4MECfHSNxmQrcrekOAr2RDgvHzJc6+Fh+NKAnFZbBw3PRLPHqhgbTzPgYZ/yMl84WVy909sTSe+3pwh7r1Go= Date: Sat, 22 Sep 2007 23:39:32 +0800 From: lepton To: jdike@karaya.com Cc: lkm Subject: [RFC PATCH] 2.6.22.6 user-mode linux: No need to new a stack for clone without CLONE_VM Message-ID: <20070922153931.GA31436@router.lepton.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5535 Lines: 182 Since we just call clone without CLONE_VM, it is no need to use anoymous mmap to get a new stack frame. Let's keep codes simple. Signed-off-by: Lepton Wu diff -X linux-2.6.22.6-uml/Documentation/dontdiff -pru linux-2.6.22.6/arch/um/os-Linux/start_up.c linux-2.6.22.6-uml/arch/um/os-Linux/start_up.c --- linux-2.6.22.6/arch/um/os-Linux/start_up.c 2007-09-14 17:41:10.000000000 +0800 +++ linux-2.6.22.6-uml/arch/um/os-Linux/start_up.c 2007-09-22 23:28:49.000000000 +0800 @@ -101,19 +101,13 @@ static void non_fatal(char *fmt, ...) fflush(stdout); } -static int start_ptraced_child(void **stack_out) +static int start_ptraced_child(void) { - void *stack; - unsigned long sp; + unsigned long sp = (((unsigned long) &sp) & ~(UM_KERN_PAGE_SIZE-1)) + + UM_KERN_PAGE_SIZE - sizeof(void *); int pid, n, status; - stack = mmap(NULL, UM_KERN_PAGE_SIZE, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - if(stack == MAP_FAILED) - fatal_perror("check_ptrace : mmap failed"); - sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *); - pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); + pid = clone(ptrace_child, sp, SIGCHLD, NULL); if(pid < 0) fatal_perror("start_ptraced_child : clone failed"); CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); @@ -123,7 +117,6 @@ static int start_ptraced_child(void **st fatal("check_ptrace : expected SIGSTOP, got status = %d", status); - *stack_out = stack; return pid; } @@ -133,7 +126,7 @@ static int start_ptraced_child(void **st * So only for SYSEMU features we test mustpanic, while normal host features * must work anyway! */ -static int stop_ptraced_child(int pid, void *stack, int exitcode, +static int stop_ptraced_child(int pid, int exitcode, int mustexit) { int status, n, ret = 0; @@ -154,8 +147,6 @@ static int stop_ptraced_child(int pid, v ret = -1; } - if(munmap(stack, UM_KERN_PAGE_SIZE) < 0) - fatal_perror("check_ptrace : munmap failed"); return ret; } @@ -207,13 +198,12 @@ __uml_setup("nosysemu", nosysemu_cmd_par static void __init check_sysemu(void) { - void *stack; unsigned long regs[MAX_REG_NR]; int pid, n, status, count=0; non_fatal("Checking syscall emulation patch for ptrace..."); sysemu_supported = 0; - pid = start_ptraced_child(&stack); + pid = start_ptraced_child(); if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) goto fail; @@ -240,7 +230,7 @@ static void __init check_sysemu(void) goto fail; } - if (stop_ptraced_child(pid, stack, 0, 0) < 0) + if (stop_ptraced_child(pid, 0, 0) < 0) goto fail_stopped; sysemu_supported = 1; @@ -248,7 +238,7 @@ static void __init check_sysemu(void) set_using_sysemu(!force_sysemu_disabled); non_fatal("Checking advanced syscall emulation patch for ptrace..."); - pid = start_ptraced_child(&stack); + pid = start_ptraced_child(); if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *) PTRACE_O_TRACESYSGOOD) < 0)) @@ -279,7 +269,7 @@ static void __init check_sysemu(void) fatal("check_ptrace : expected SIGTRAP or " "(SIGTRAP | 0x80), got status = %d", status); } - if (stop_ptraced_child(pid, stack, 0, 0) < 0) + if (stop_ptraced_child(pid, 0, 0) < 0) goto fail_stopped; sysemu_supported = 2; @@ -290,18 +280,17 @@ static void __init check_sysemu(void) return; fail: - stop_ptraced_child(pid, stack, 1, 0); + stop_ptraced_child(pid, 1, 0); fail_stopped: non_fatal("missing\n"); } static void __init check_ptrace(void) { - void *stack; int pid, syscall, n, status; non_fatal("Checking that ptrace can change system call numbers..."); - pid = start_ptraced_child(&stack); + pid = start_ptraced_child(); if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *) PTRACE_O_TRACESYSGOOD) < 0)) @@ -331,7 +320,7 @@ static void __init check_ptrace(void) break; } } - stop_ptraced_child(pid, stack, 0, 1); + stop_ptraced_child(pid, 0, 1); non_fatal("OK\n"); check_sysemu(); } @@ -412,11 +401,10 @@ __uml_setup("noptraceldt", noptraceldt_c static inline void check_skas3_ptrace_faultinfo(void) { struct ptrace_faultinfo fi; - void *stack; int pid, n; non_fatal(" - PTRACE_FAULTINFO..."); - pid = start_ptraced_child(&stack); + pid = start_ptraced_child(); n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); if (n < 0) { @@ -434,13 +422,12 @@ static inline void check_skas3_ptrace_fa } init_registers(pid); - stop_ptraced_child(pid, stack, 1, 1); + stop_ptraced_child(pid, 1, 1); } static inline void check_skas3_ptrace_ldt(void) { #ifdef PTRACE_LDT - void *stack; int pid, n; unsigned char ldtbuf[40]; struct ptrace_ldt ldt_op = (struct ptrace_ldt) { @@ -449,7 +436,7 @@ static inline void check_skas3_ptrace_ld .bytecount = sizeof(ldtbuf)}; non_fatal(" - PTRACE_LDT..."); - pid = start_ptraced_child(&stack); + pid = start_ptraced_child(); n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); if (n < 0) { @@ -467,7 +454,7 @@ static inline void check_skas3_ptrace_ld non_fatal("found, but use is disabled\n"); } - stop_ptraced_child(pid, stack, 1, 1); + stop_ptraced_child(pid, 1, 1); #else /* PTRACE_LDT might be disabled via cmdline option. * We want to override this, else we might use the stub - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/