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|
Turns off syscall emulation patch for ptrace (SYSEMU) on.
SYSEMU is a performance-patch introduced by Laurent Vivier. It changes
behaviour of ptrace() and helps reducing host context switch rate.
To make it working, you need a kernel patch for your host, too.
See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
---
uml-linux-2.6.7-paolo/arch/um/kernel/process.c | 35 ++++++++++
uml-linux-2.6.7-paolo/arch/um/kernel/skas/include/ptrace-skas.h | 7 ++
uml-linux-2.6.7-paolo/arch/um/kernel/skas/process.c | 22 ++++++
3 files changed, 64 insertions(+)
diff -puN arch/um/kernel/process.c~um-sysemu arch/um/kernel/process.c
--- uml-linux-2.6.7/arch/um/kernel/process.c~um-sysemu 2004-06-29 21:03:03.801059520 +0200
+++ uml-linux-2.6.7-paolo/arch/um/kernel/process.c 2004-06-29 21:03:03.806058760 +0200
@@ -19,6 +19,7 @@
#include <asm/sigcontext.h>
#include <asm/unistd.h>
#include <asm/page.h>
+#include <asm/user.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
@@ -227,6 +228,40 @@ void __init check_ptrace(void)
}
stop_ptraced_child(pid, stack, 0);
printk("OK\n");
+
+#ifdef PTRACE_SYSEMU
+ printk("Checking syscall emulation patch for ptrace...");
+ use_sysemu = 0;
+ pid = start_ptraced_child(&stack);
+ if(ptrace(PTRACE_SYSEMU, pid, 0, 0) >= 0) {
+ struct user_regs_struct regs;
+
+ if (waitpid(pid, &status, WUNTRACED) < 0)
+ panic("check_ptrace : wait failed, errno = %d", errno);
+ if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
+ 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);
+
+ stop_ptraced_child(pid, stack, 0);
+
+ printk("OK\n");
+ use_sysemu = 1;
+ }
+ else
+ {
+ printk("missing\n");
+ stop_ptraced_child(pid, stack, 1);
+ }
+
+# endif /* PTRACE_SYSEMU */
}
int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
diff -puN arch/um/kernel/skas/include/ptrace-skas.h~um-sysemu arch/um/kernel/skas/include/ptrace-skas.h
--- uml-linux-2.6.7/arch/um/kernel/skas/include/ptrace-skas.h~um-sysemu 2004-06-29 21:03:03.802059368 +0200
+++ uml-linux-2.6.7-paolo/arch/um/kernel/skas/include/ptrace-skas.h 2004-06-29 21:03:03.806058760 +0200
@@ -10,6 +10,13 @@
#ifdef UML_CONFIG_MODE_SKAS
+/* syscall emulation path in ptrace */
+
+#ifndef PTRACE_SYSEMU
+#define PTRACE_SYSEMU 31
+#endif
+extern int use_sysemu;
+
#include "skas_ptregs.h"
#define HOST_FRAME_SIZE 17
diff -puN arch/um/kernel/skas/process.c~um-sysemu arch/um/kernel/skas/process.c
--- uml-linux-2.6.7/arch/um/kernel/skas/process.c~um-sysemu 2004-06-29 21:03:03.803059216 +0200
+++ uml-linux-2.6.7-paolo/arch/um/kernel/skas/process.c 2004-06-29 21:03:03.806058760 +0200
@@ -28,6 +28,10 @@
#include "chan_user.h"
#include "signal_user.h"
+#ifdef PTRACE_SYSEMU
+int use_sysemu = 0;
+#endif
+
int is_skas_winch(int pid, int fd, void *data)
{
if(pid != getpid())
@@ -68,6 +72,10 @@ static void handle_trap(int pid, union u
return;
}
+#ifdef PTRACE_SYSEMU
+ if (!use_sysemu)
+ {
+#endif
err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
if(err < 0)
panic("handle_trap - nullifying syscall failed errno = %d\n",
@@ -82,6 +90,9 @@ static void handle_trap(int pid, union u
if((err < 0) || !WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
panic("handle_trap - failed to wait at end of syscall, "
"errno = %d, status = %d\n", errno, status);
+#ifdef PTRACE_SYSEMU
+ }
+#endif
handle_syscall(regs);
}
@@ -139,6 +150,11 @@ void userspace(union uml_pt_regs *regs)
restore_registers(regs);
+#ifdef PTRACE_SYSEMU
+ if (use_sysemu)
+ err = ptrace(PTRACE_SYSEMU, pid, 0, 0);
+ else
+#endif
err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
if(err)
panic("userspace - PTRACE_SYSCALL failed, errno = %d\n",
@@ -177,6 +193,12 @@ void userspace(union uml_pt_regs *regs)
restore_registers(regs);
+#ifdef PTRACE_SYSEMU
+ if (use_sysemu)
+ op = singlestepping_skas() ? PTRACE_SINGLESTEP :
+ PTRACE_SYSEMU;
+ else
+#endif
op = singlestepping_skas() ? PTRACE_SINGLESTEP :
PTRACE_SYSCALL;
err = ptrace(op, pid, 0, 0);
_
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