From: Jeff Dike <jdike@addtoit.com>
To: Andrew Morton <akpm@osdl.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
uml-devel <user-mode-linux-devel@lists.sourceforge.net>
Subject: [uml-devel] [ PATCH 2/4] UML - Kernel segfaults should dump proper registers
Date: Wed, 4 Apr 2007 20:34:02 -0400 [thread overview]
Message-ID: <20070405003402.GA13275@c2.user-mode-linux.org> (raw)
If there's a segfault inside the kernel, we want a dump of the registers
at the point of the segfault, not the registers at the point of
calling panic or the last userspace registers.
sig_handler_common_skas now uses a static register set in the case
of a SIGSEGV to avoid messing up the process registers if the
segfault turns out to be non-fatal.
The architecture sigcontext-to-pt_regs copying code was repurposed
to copy data out of the SEGV stack frame.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
--
arch/um/include/common-offsets.h | 2 +
arch/um/include/kern_util.h | 2 +
arch/um/kernel/trap.c | 10 ++++++---
arch/um/os-Linux/skas/trap.c | 15 ++++++++++++--
arch/um/sys-i386/signal.c | 41 ++++++++++++++++++++++-----------------
arch/um/sys-x86_64/signal.c | 30 ++++++++++++++++++++++++++++
6 files changed, 78 insertions(+), 22 deletions(-)
Index: linux-2.6.21-mm/arch/um/kernel/trap.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/kernel/trap.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/kernel/trap.c 2007-04-02 12:19:07.000000000 -0400
@@ -170,8 +170,10 @@ unsigned long segv(struct faultinfo fi,
flush_tlb_kernel_vm();
return 0;
}
- else if(current->mm == NULL)
- panic("Segfault with no mm");
+ else if(current->mm == NULL) {
+ show_regs(container_of(regs, struct pt_regs, regs));
+ panic("Segfault with no mm");
+ }
if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
@@ -194,9 +196,11 @@ unsigned long segv(struct faultinfo fi,
else if(!is_user && arch_fixup(ip, regs))
return 0;
- if(!is_user)
+ if(!is_user) {
+ show_regs(container_of(regs, struct pt_regs, regs));
panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
address, ip);
+ }
if (err == -EACCES) {
si.si_signo = SIGBUS;
Index: linux-2.6.21-mm/arch/um/include/kern_util.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/kern_util.h 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/kern_util.h 2007-04-02 12:19:07.000000000 -0400
@@ -116,4 +116,6 @@ extern void log_info(char *fmt, ...) __a
extern int __cant_sleep(void);
extern void sigio_handler(int sig, union uml_pt_regs *regs);
+extern void copy_sc(union uml_pt_regs *regs, void *from);
+
#endif
Index: linux-2.6.21-mm/arch/um/include/common-offsets.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/common-offsets.h 2007-04-02 12:18:49.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/common-offsets.h 2007-04-02 12:19:07.000000000 -0400
@@ -24,5 +24,7 @@ DEFINE(UM_ELF_CLASS, ELF_CLASS);
DEFINE(UM_ELFCLASS32, ELFCLASS32);
DEFINE(UM_ELFCLASS64, ELFCLASS64);
+DEFINE(UM_NR_CPUS, NR_CPUS);
+
/* For crypto assembler code. */
DEFINE(crypto_tfm_ctx_offset, offsetof(struct crypto_tfm, __crt_ctx));
Index: linux-2.6.21-mm/arch/um/os-Linux/skas/trap.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/skas/trap.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/skas/trap.c 2007-04-02 12:19:07.000000000 -0400
@@ -15,6 +15,8 @@
#include "sysdep/ptrace_user.h"
#include "os.h"
+static union uml_pt_regs ksig_regs[UM_NR_CPUS];
+
void sig_handler_common_skas(int sig, void *sc_ptr)
{
struct sigcontext *sc = sc_ptr;
@@ -27,10 +29,19 @@ void sig_handler_common_skas(int sig, vo
* the process will die.
* XXX Figure out why this is better than SA_NODEFER
*/
- if(sig == SIGSEGV)
+ if(sig == SIGSEGV) {
change_sig(SIGSEGV, 1);
+ /* For segfaults, we want the data from the
+ * sigcontext. In this case, we don't want to mangle
+ * the process registers, so use a static set of
+ * registers. For other signals, the process
+ * registers are OK.
+ */
+ r = &ksig_regs[cpu()];
+ copy_sc(r, sc_ptr);
+ }
+ else r = TASK_REGS(get_current());
- r = TASK_REGS(get_current());
save_user = r->skas.is_user;
r->skas.is_user = 0;
if ( sig == SIGFPE || sig == SIGSEGV ||
Index: linux-2.6.21-mm/arch/um/sys-i386/signal.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/sys-i386/signal.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/sys-i386/signal.c 2007-04-02 12:19:07.000000000 -0400
@@ -18,6 +18,28 @@
#include "skas.h"
+void copy_sc(union uml_pt_regs *regs, void *from)
+{
+ struct sigcontext *sc = from;
+
+ REGS_GS(regs->skas.regs) = sc->gs;
+ REGS_FS(regs->skas.regs) = sc->fs;
+ REGS_ES(regs->skas.regs) = sc->es;
+ REGS_DS(regs->skas.regs) = sc->ds;
+ REGS_EDI(regs->skas.regs) = sc->edi;
+ REGS_ESI(regs->skas.regs) = sc->esi;
+ REGS_EBP(regs->skas.regs) = sc->ebp;
+ REGS_SP(regs->skas.regs) = sc->esp;
+ REGS_EBX(regs->skas.regs) = sc->ebx;
+ REGS_EDX(regs->skas.regs) = sc->edx;
+ REGS_ECX(regs->skas.regs) = sc->ecx;
+ REGS_EAX(regs->skas.regs) = sc->eax;
+ REGS_IP(regs->skas.regs) = sc->eip;
+ REGS_CS(regs->skas.regs) = sc->cs;
+ REGS_EFLAGS(regs->skas.regs) = sc->eflags;
+ REGS_SS(regs->skas.regs) = sc->ss;
+}
+
static int copy_sc_from_user_skas(struct pt_regs *regs,
struct sigcontext __user *from)
{
@@ -30,25 +52,10 @@ static int copy_sc_from_user_skas(struct
if(err)
return err;
- REGS_GS(regs->regs.skas.regs) = sc.gs;
- REGS_FS(regs->regs.skas.regs) = sc.fs;
- REGS_ES(regs->regs.skas.regs) = sc.es;
- REGS_DS(regs->regs.skas.regs) = sc.ds;
- REGS_EDI(regs->regs.skas.regs) = sc.edi;
- REGS_ESI(regs->regs.skas.regs) = sc.esi;
- REGS_EBP(regs->regs.skas.regs) = sc.ebp;
- REGS_SP(regs->regs.skas.regs) = sc.esp;
- REGS_EBX(regs->regs.skas.regs) = sc.ebx;
- REGS_EDX(regs->regs.skas.regs) = sc.edx;
- REGS_ECX(regs->regs.skas.regs) = sc.ecx;
- REGS_EAX(regs->regs.skas.regs) = sc.eax;
- REGS_IP(regs->regs.skas.regs) = sc.eip;
- REGS_CS(regs->regs.skas.regs) = sc.cs;
- REGS_EFLAGS(regs->regs.skas.regs) = sc.eflags;
- REGS_SS(regs->regs.skas.regs) = sc.ss;
+ copy_sc(®s->regs, &sc);
err = restore_fp_registers(userspace_pid[0], fpregs);
- if(err < 0){
+ if(err < 0) {
printk("copy_sc_from_user_skas - PTRACE_SETFPREGS failed, "
"errno = %d\n", -err);
return err;
Index: linux-2.6.21-mm/arch/um/sys-x86_64/signal.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/sys-x86_64/signal.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/sys-x86_64/signal.c 2007-04-02 12:19:07.000000000 -0400
@@ -20,6 +20,36 @@
#include "skas.h"
+void copy_sc(union uml_pt_regs *regs, void *from)
+{
+ struct sigcontext *sc = from;
+
+#define GETREG(regs, regno, sc, regname) \
+ (regs)->skas.regs[(regno) / sizeof(unsigned long)] = (sc)->regname
+
+ GETREG(regs, R8, sc, r8);
+ GETREG(regs, R9, sc, r9);
+ GETREG(regs, R10, sc, r10);
+ GETREG(regs, R11, sc, r11);
+ GETREG(regs, R12, sc, r12);
+ GETREG(regs, R13, sc, r13);
+ GETREG(regs, R14, sc, r14);
+ GETREG(regs, R15, sc, r15);
+ GETREG(regs, RDI, sc, rdi);
+ GETREG(regs, RSI, sc, rsi);
+ GETREG(regs, RBP, sc, rbp);
+ GETREG(regs, RBX, sc, rbx);
+ GETREG(regs, RDX, sc, rdx);
+ GETREG(regs, RAX, sc, rax);
+ GETREG(regs, RCX, sc, rcx);
+ GETREG(regs, RSP, sc, rsp);
+ GETREG(regs, RIP, sc, rip);
+ GETREG(regs, EFLAGS, sc, eflags);
+ GETREG(regs, CS, sc, cs);
+
+#undef GETREG
+}
+
static int copy_sc_from_user_skas(struct pt_regs *regs,
struct sigcontext __user *from)
{
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
WARNING: multiple messages have this Message-ID (diff)
From: Jeff Dike <jdike@addtoit.com>
To: Andrew Morton <akpm@osdl.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
uml-devel <user-mode-linux-devel@lists.sourceforge.net>
Subject: [ PATCH 2/4] UML - Kernel segfaults should dump proper registers
Date: Wed, 4 Apr 2007 20:34:02 -0400 [thread overview]
Message-ID: <20070405003402.GA13275@c2.user-mode-linux.org> (raw)
If there's a segfault inside the kernel, we want a dump of the registers
at the point of the segfault, not the registers at the point of
calling panic or the last userspace registers.
sig_handler_common_skas now uses a static register set in the case
of a SIGSEGV to avoid messing up the process registers if the
segfault turns out to be non-fatal.
The architecture sigcontext-to-pt_regs copying code was repurposed
to copy data out of the SEGV stack frame.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
--
arch/um/include/common-offsets.h | 2 +
arch/um/include/kern_util.h | 2 +
arch/um/kernel/trap.c | 10 ++++++---
arch/um/os-Linux/skas/trap.c | 15 ++++++++++++--
arch/um/sys-i386/signal.c | 41 ++++++++++++++++++++++-----------------
arch/um/sys-x86_64/signal.c | 30 ++++++++++++++++++++++++++++
6 files changed, 78 insertions(+), 22 deletions(-)
Index: linux-2.6.21-mm/arch/um/kernel/trap.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/kernel/trap.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/kernel/trap.c 2007-04-02 12:19:07.000000000 -0400
@@ -170,8 +170,10 @@ unsigned long segv(struct faultinfo fi,
flush_tlb_kernel_vm();
return 0;
}
- else if(current->mm == NULL)
- panic("Segfault with no mm");
+ else if(current->mm == NULL) {
+ show_regs(container_of(regs, struct pt_regs, regs));
+ panic("Segfault with no mm");
+ }
if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
@@ -194,9 +196,11 @@ unsigned long segv(struct faultinfo fi,
else if(!is_user && arch_fixup(ip, regs))
return 0;
- if(!is_user)
+ if(!is_user) {
+ show_regs(container_of(regs, struct pt_regs, regs));
panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
address, ip);
+ }
if (err == -EACCES) {
si.si_signo = SIGBUS;
Index: linux-2.6.21-mm/arch/um/include/kern_util.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/kern_util.h 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/kern_util.h 2007-04-02 12:19:07.000000000 -0400
@@ -116,4 +116,6 @@ extern void log_info(char *fmt, ...) __a
extern int __cant_sleep(void);
extern void sigio_handler(int sig, union uml_pt_regs *regs);
+extern void copy_sc(union uml_pt_regs *regs, void *from);
+
#endif
Index: linux-2.6.21-mm/arch/um/include/common-offsets.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/common-offsets.h 2007-04-02 12:18:49.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/common-offsets.h 2007-04-02 12:19:07.000000000 -0400
@@ -24,5 +24,7 @@ DEFINE(UM_ELF_CLASS, ELF_CLASS);
DEFINE(UM_ELFCLASS32, ELFCLASS32);
DEFINE(UM_ELFCLASS64, ELFCLASS64);
+DEFINE(UM_NR_CPUS, NR_CPUS);
+
/* For crypto assembler code. */
DEFINE(crypto_tfm_ctx_offset, offsetof(struct crypto_tfm, __crt_ctx));
Index: linux-2.6.21-mm/arch/um/os-Linux/skas/trap.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/skas/trap.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/skas/trap.c 2007-04-02 12:19:07.000000000 -0400
@@ -15,6 +15,8 @@
#include "sysdep/ptrace_user.h"
#include "os.h"
+static union uml_pt_regs ksig_regs[UM_NR_CPUS];
+
void sig_handler_common_skas(int sig, void *sc_ptr)
{
struct sigcontext *sc = sc_ptr;
@@ -27,10 +29,19 @@ void sig_handler_common_skas(int sig, vo
* the process will die.
* XXX Figure out why this is better than SA_NODEFER
*/
- if(sig == SIGSEGV)
+ if(sig == SIGSEGV) {
change_sig(SIGSEGV, 1);
+ /* For segfaults, we want the data from the
+ * sigcontext. In this case, we don't want to mangle
+ * the process registers, so use a static set of
+ * registers. For other signals, the process
+ * registers are OK.
+ */
+ r = &ksig_regs[cpu()];
+ copy_sc(r, sc_ptr);
+ }
+ else r = TASK_REGS(get_current());
- r = TASK_REGS(get_current());
save_user = r->skas.is_user;
r->skas.is_user = 0;
if ( sig == SIGFPE || sig == SIGSEGV ||
Index: linux-2.6.21-mm/arch/um/sys-i386/signal.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/sys-i386/signal.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/sys-i386/signal.c 2007-04-02 12:19:07.000000000 -0400
@@ -18,6 +18,28 @@
#include "skas.h"
+void copy_sc(union uml_pt_regs *regs, void *from)
+{
+ struct sigcontext *sc = from;
+
+ REGS_GS(regs->skas.regs) = sc->gs;
+ REGS_FS(regs->skas.regs) = sc->fs;
+ REGS_ES(regs->skas.regs) = sc->es;
+ REGS_DS(regs->skas.regs) = sc->ds;
+ REGS_EDI(regs->skas.regs) = sc->edi;
+ REGS_ESI(regs->skas.regs) = sc->esi;
+ REGS_EBP(regs->skas.regs) = sc->ebp;
+ REGS_SP(regs->skas.regs) = sc->esp;
+ REGS_EBX(regs->skas.regs) = sc->ebx;
+ REGS_EDX(regs->skas.regs) = sc->edx;
+ REGS_ECX(regs->skas.regs) = sc->ecx;
+ REGS_EAX(regs->skas.regs) = sc->eax;
+ REGS_IP(regs->skas.regs) = sc->eip;
+ REGS_CS(regs->skas.regs) = sc->cs;
+ REGS_EFLAGS(regs->skas.regs) = sc->eflags;
+ REGS_SS(regs->skas.regs) = sc->ss;
+}
+
static int copy_sc_from_user_skas(struct pt_regs *regs,
struct sigcontext __user *from)
{
@@ -30,25 +52,10 @@ static int copy_sc_from_user_skas(struct
if(err)
return err;
- REGS_GS(regs->regs.skas.regs) = sc.gs;
- REGS_FS(regs->regs.skas.regs) = sc.fs;
- REGS_ES(regs->regs.skas.regs) = sc.es;
- REGS_DS(regs->regs.skas.regs) = sc.ds;
- REGS_EDI(regs->regs.skas.regs) = sc.edi;
- REGS_ESI(regs->regs.skas.regs) = sc.esi;
- REGS_EBP(regs->regs.skas.regs) = sc.ebp;
- REGS_SP(regs->regs.skas.regs) = sc.esp;
- REGS_EBX(regs->regs.skas.regs) = sc.ebx;
- REGS_EDX(regs->regs.skas.regs) = sc.edx;
- REGS_ECX(regs->regs.skas.regs) = sc.ecx;
- REGS_EAX(regs->regs.skas.regs) = sc.eax;
- REGS_IP(regs->regs.skas.regs) = sc.eip;
- REGS_CS(regs->regs.skas.regs) = sc.cs;
- REGS_EFLAGS(regs->regs.skas.regs) = sc.eflags;
- REGS_SS(regs->regs.skas.regs) = sc.ss;
+ copy_sc(®s->regs, &sc);
err = restore_fp_registers(userspace_pid[0], fpregs);
- if(err < 0){
+ if(err < 0) {
printk("copy_sc_from_user_skas - PTRACE_SETFPREGS failed, "
"errno = %d\n", -err);
return err;
Index: linux-2.6.21-mm/arch/um/sys-x86_64/signal.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/sys-x86_64/signal.c 2007-04-02 12:19:04.000000000 -0400
+++ linux-2.6.21-mm/arch/um/sys-x86_64/signal.c 2007-04-02 12:19:07.000000000 -0400
@@ -20,6 +20,36 @@
#include "skas.h"
+void copy_sc(union uml_pt_regs *regs, void *from)
+{
+ struct sigcontext *sc = from;
+
+#define GETREG(regs, regno, sc, regname) \
+ (regs)->skas.regs[(regno) / sizeof(unsigned long)] = (sc)->regname
+
+ GETREG(regs, R8, sc, r8);
+ GETREG(regs, R9, sc, r9);
+ GETREG(regs, R10, sc, r10);
+ GETREG(regs, R11, sc, r11);
+ GETREG(regs, R12, sc, r12);
+ GETREG(regs, R13, sc, r13);
+ GETREG(regs, R14, sc, r14);
+ GETREG(regs, R15, sc, r15);
+ GETREG(regs, RDI, sc, rdi);
+ GETREG(regs, RSI, sc, rsi);
+ GETREG(regs, RBP, sc, rbp);
+ GETREG(regs, RBX, sc, rbx);
+ GETREG(regs, RDX, sc, rdx);
+ GETREG(regs, RAX, sc, rax);
+ GETREG(regs, RCX, sc, rcx);
+ GETREG(regs, RSP, sc, rsp);
+ GETREG(regs, RIP, sc, rip);
+ GETREG(regs, EFLAGS, sc, eflags);
+ GETREG(regs, CS, sc, cs);
+
+#undef GETREG
+}
+
static int copy_sc_from_user_skas(struct pt_regs *regs,
struct sigcontext __user *from)
{
next reply other threads:[~2007-04-05 0:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-05 0:34 Jeff Dike [this message]
2007-04-05 0:34 ` [ PATCH 2/4] UML - Kernel segfaults should dump proper registers Jeff Dike
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070405003402.GA13275@c2.user-mode-linux.org \
--to=jdike@addtoit.com \
--cc=akpm@osdl.org \
--cc=linux-kernel@vger.kernel.org \
--cc=user-mode-linux-devel@lists.sourceforge.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.