Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964832AbVKQUhZ (ORCPT ); Thu, 17 Nov 2005 15:37:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964835AbVKQUhZ (ORCPT ); Thu, 17 Nov 2005 15:37:25 -0500 Received: from spirit.analogic.com ([204.178.40.4]:47369 "EHLO spirit.analogic.com") by vger.kernel.org with ESMTP id S964832AbVKQUhY convert rfc822-to-8bit (ORCPT ); Thu, 17 Nov 2005 15:37:24 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 In-Reply-To: <200511172110.jAHLASIB010204@ccure.user-mode-linux.org> References: <200511172110.jAHLASIB010204@ccure.user-mode-linux.org> X-OriginalArrivalTime: 17 Nov 2005 20:37:23.0545 (UTC) FILETIME=[B6EC6C90:01C5EBB6] Content-class: urn:content-classes:message Subject: Re: [PATCH 3/4] UML - Properly invoke x86_64 system calls Date: Thu, 17 Nov 2005 15:37:14 -0500 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH 3/4] UML - Properly invoke x86_64 system calls Thread-Index: AcXrtrbzsoZ7EXHuTwKLFtvcewZ0Qw== From: "linux-os \(Dick Johnson\)" To: "Jeff Dike" Cc: , "Linux kernel" , Reply-To: "linux-os \(Dick Johnson\)" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7959 Lines: 212 On Thu, 17 Nov 2005, Jeff Dike wrote: > This patch makes stub_segv use the stub_syscall macros. This was > needed anyway, but the bug that prompted this was the discovery that > gcc was storing stuff in RCX, which is trashed across a system > call. But the C-calling convention used by gcc for 32-bit systems is supposed to allow the called-function to destroy general- purpose registers but not index registers. In other words, ECX, EDX are supposed to be available and EAX is used for return-values. The register size isn't supposed to have anything to do with it (longword/quadword)! In 64-bit world, the same is supposed to apply as well. If RCX is now precious, it's a GCC bug that should be fixed. Yes? This is exactly the sort of problem that the new macros fix. > There is a stub_syscall0 for getpid. > stub_segv was changed to be a libc file, and that caused some > include changes. > > Signed-off-by: Jeff Dike > > Index: linux-2.6.15/arch/um/include/sysdep-i386/stub.h > =================================================================== > --- linux-2.6.15.orig/arch/um/include/sysdep-i386/stub.h 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/include/sysdep-i386/stub.h 2005-11-17 14:59:55.000000000 -0500 > @@ -16,6 +16,15 @@ > #define STUB_MMAP_NR __NR_mmap2 > #define MMAP_OFFSET(o) ((o) >> PAGE_SHIFT) > > +static inline long stub_syscall0(long syscall) > +{ > + long ret; > + > + __asm__ volatile ("int $0x80" : "=a" (ret) : "0" (syscall)); > + > + return ret; > +} > + > static inline long stub_syscall1(long syscall, long arg1) > { > long ret; > Index: linux-2.6.15/arch/um/include/sysdep-x86_64/stub.h > =================================================================== > --- linux-2.6.15.orig/arch/um/include/sysdep-x86_64/stub.h 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/include/sysdep-x86_64/stub.h 2005-11-17 14:59:55.000000000 -0500 > @@ -6,7 +6,6 @@ > #ifndef __SYSDEP_STUB_H > #define __SYSDEP_STUB_H > > -#include > #include > #include > > @@ -20,6 +19,17 @@ > #define __syscall_clobber "r11","rcx","memory" > #define __syscall "syscall" > > +static inline long stub_syscall0(long syscall) > +{ > + long ret; > + > + __asm__ volatile (__syscall > + : "=a" (ret) > + : "0" (syscall) : __syscall_clobber ); > + > + return ret; > +} > + > static inline long stub_syscall2(long syscall, long arg1, long arg2) > { > long ret; > Index: linux-2.6.15/arch/um/sys-i386/Makefile > =================================================================== > --- linux-2.6.15.orig/arch/um/sys-i386/Makefile 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/sys-i386/Makefile 2005-11-17 14:59:55.000000000 -0500 > @@ -5,7 +5,7 @@ > obj-$(CONFIG_HIGHMEM) += highmem.o > obj-$(CONFIG_MODULES) += module.o > > -USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o > +USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o stub_segv.o > > SYMLINKS = bitops.c semaphore.c highmem.c module.c > > Index: linux-2.6.15/arch/um/sys-i386/stub_segv.c > =================================================================== > --- linux-2.6.15.orig/arch/um/sys-i386/stub_segv.c 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/sys-i386/stub_segv.c 2005-11-17 14:59:55.000000000 -0500 > @@ -3,9 +3,11 @@ > * Licensed under the GPL > */ > > -#include > +#include > +#include /* The only way I can see to get sigset_t */ > #include > #include "uml-config.h" > +#include "sysdep/stub.h" > #include "sysdep/sigcontext.h" > #include "sysdep/faultinfo.h" > > @@ -13,13 +15,14 @@ > stub_segv_handler(int sig) > { > struct sigcontext *sc = (struct sigcontext *) (&sig + 1); > + int pid; > > GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA), > sc); > > - __asm__("movl %0, %%eax ; int $0x80": : "g" (__NR_getpid)); > - __asm__("movl %%eax, %%ebx ; movl %0, %%eax ; movl %1, %%ecx ;" > - "int $0x80": : "g" (__NR_kill), "g" (SIGUSR1)); > + pid = stub_syscall0(__NR_getpid); > + stub_syscall2(__NR_kill, pid, SIGUSR1); > + > /* Load pointer to sigcontext into esp, since we need to leave > * the stack in its original form when we do the sigreturn here, by > * hand. > Index: linux-2.6.15/arch/um/sys-x86_64/Makefile > =================================================================== > --- linux-2.6.15.orig/arch/um/sys-x86_64/Makefile 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/sys-x86_64/Makefile 2005-11-17 14:59:55.000000000 -0500 > @@ -12,7 +12,7 @@ > obj-y := ksyms.o > obj-$(CONFIG_MODULES) += module.o um_module.o > > -USER_OBJS := ptrace_user.o sigcontext.o > +USER_OBJS := ptrace_user.o sigcontext.o stub_segv.o > > SYMLINKS = bitops.c csum-copy.S csum-partial.c csum-wrappers.c ldt.c memcpy.S \ > thunk.S module.c > Index: linux-2.6.15/arch/um/sys-x86_64/stub_segv.c > =================================================================== > --- linux-2.6.15.orig/arch/um/sys-x86_64/stub_segv.c 2005-11-17 14:59:30.000000000 -0500 > +++ linux-2.6.15/arch/um/sys-x86_64/stub_segv.c 2005-11-17 15:12:23.000000000 -0500 > @@ -3,14 +3,14 @@ > * Licensed under the GPL > */ > > -#include > +#include > +#include > #include > #include > -#include > #include "uml-config.h" > #include "sysdep/sigcontext.h" > #include "sysdep/faultinfo.h" > -#include > +#include "sysdep/stub.h" > > /* Copied from sys-x86_64/signal.c - Can't find an equivalent definition > * in the libc headers anywhere. > @@ -31,21 +31,21 @@ > stub_segv_handler(int sig) > { > struct ucontext *uc; > + int pid; > > __asm__("movq %%rdx, %0" : "=g" (uc) :); > GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA), > &uc->uc_mcontext); > > - __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid)); > - __asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;" > - "syscall": : "g" (__NR_kill), "g" (SIGUSR1) : > - "%rdi", "%rax", "%rsi"); > + pid = stub_syscall0(__NR_getpid); > + stub_syscall2(__NR_kill, pid, SIGUSR1); > + > /* sys_sigreturn expects that the stack pointer will be 8 bytes into > * the signal frame. So, we use the ucontext pointer, which we know > * already, to get the signal frame pointer, and add 8 to that. > */ > - __asm__("movq %0, %%rsp": : > + __asm__("movq %0, %%rsp; movq %1, %%rax ; syscall": : > "g" ((unsigned long) container_of(uc, struct rt_sigframe, > - uc) + 8)); > - __asm__("movq %0, %%rax ; syscall" : : "g" (__NR_rt_sigreturn)); > + uc) + 8), > + "g" (__NR_rt_sigreturn)); > } > > - > 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/ > Cheers, Dick Johnson Penguin : Linux version 2.6.13.4 on an i686 machine (5589.44 BogoMips). Warning : 98.36% of all statistics are fiction. . **************************************************************** The information transmitted in this message is confidential and may be privileged. 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