[Bengt Ahlgren] 8.3-PRERELEASE panic in linux emulation

[Konstantin Belousov]

On Fri, Feb 24, 2012 at 01:27:24PM +0100, Bengt Ahlgren wrote:
> Hello!
> 
> Perhaps emulation@ is a better place to report this problem?
> 
> Bengt
> 

> From: Bengt Ahlgren <bengta at sics.se>
> To: stable at freebsd.org
> Subject: 8.3-PRERELEASE panic in linux emulation
> Date: Thu, 23 Feb 2012 17:26:32 +0100
> 
> Hi!
> 
> I get a consistent panic when starting acroread after updating to
> 8.3-PRERELEASE.  An 8.2-STABLE from Feb 4th was OK.  Can provide more
> info if needed.
> 
> Bengt
> 
> FreeBSD xx.yy.zz 8.3-PRERELEASE FreeBSD 8.3-PRERELEASE #13 r231999: Wed Feb 22 21:01:38 CET 2012     bengta at P142.sics.se:/usr/obj/usr/src/sys/P142-82  i386
> 
> Fatal trap 12: page fault while in kernel mode
> fault virtual address   = 0xbfbfdffc
> fault code              = supervisor write, page not present
> instruction pointer     = 0x20:0xc50b396c
> stack pointer           = 0x28:0xe7481a6c
> frame pointer           = 0x28:0xe7481a90
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, def32 1, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 1997 (bash)
> trap number             = 12
> panic: page fault
> KDB: stack backtrace:
> db_trace_self_wrapper(c091af2a,70797420,78302065,a0d6231,c5d6b600,...) at db_trace_self_wrapper+0x26
> kdb_backtrace(c0919061,c09b49a0,c0900251,e7481910,e7481910,...) at kdb_backtrace+0x2a
> panic(c0900251,c0941cab,c5c246e8,1,1,...) at panic+0xaf
> trap_fatal(c0670d02,0,e7481964,80400,c5c24580,...) at trap_fatal+0x353
> trap_pfault(e74819cc,bfbfe190,c5c24580,202,c5cecac0,...) at trap_pfault+0x87
> trap(e7481a2c) at trap+0x453
> calltrap() at calltrap+0x6
> --- trap 0xc, eip = 0xc50b396c, esp = 0xe7481a6c, ebp = 0xe7481a90 ---
> elf_linux_fixup(e7481c0c,e7481b98,c065ca92,c60ffce8,100000,...) at elf_linux_fixup+0x33c
> kern_execve(c5c24580,e7481c3c,0,8112710,8116cd8,...) at kern_execve+0x7d6
> linux_execve(c5c24580,e7481cec,c,c,c,...) at linux_execve+0xa7
> syscall(e7481d28) at syscall+0x372
> Xint0x80_syscall() at Xint0x80_syscall+0x21
> --- syscall (11, Linux ELF, linux_execve), eip = 0x281e0d4a, esp = 0xbfbfd644, ebp = 0xbfbfd7e8 ---
> 
> #0  doadump () at pcpu.h:244
> #1  0xc05de609 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:441
> #2  0xc05de84f in panic (fmt=Variable "fmt" is not available.
> ) at /usr/src/sys/kern/kern_shutdown.c:614
> #3  0xc08b22c3 in trap_fatal (frame=0xe7481a2c, eva=3217022972) at /usr/src/sys/i386/i386/trap.c:981
> #4  0xc08b2357 in trap_pfault (frame=0xe7481a2c, usermode=0, eva=3217022972) at /usr/src/sys/i386/i386/trap.c:843
> #5  0xc08b3133 in trap (frame=0xe7481a2c) at /usr/src/sys/i386/i386/trap.c:562
> #6  0xc089bedc in calltrap () at /usr/src/sys/i386/i386/exception.s:168
> #7  0xc50b396c in elf_linux_fixup (stack_base=0xe7481c0c, imgp=0xe7481b98) at /usr/src/sys/modules/linux/../../i386/linux/linux_sysvec.c:288
> #8  0xc05ac636 in kern_execve (td=0xc5c24580, args=0xe7481c3c, mac_p=0x0) at /usr/src/sys/kern/kern_exec.c:551
> #9  0xc50ab387 in linux_execve (td=0xc5c24580, args=0xe7481cec) at /usr/src/sys/modules/linux/../../i386/linux/linux_machdep.c:143
> #10 0xc08b2902 in syscall (frame=0xe7481d28) at subr_syscall.c:114
> #11 0xc089bf41 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:266
> #12 0x00000033 in ?? ()
> 
I am not sure if this is the real cause of your panic, but the line from
the backtrace indeed has a bug. Please try the change below.

diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 7634138..d4e23e1 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -227,11 +227,11 @@ linux_fixup(register_t **stack_base, struct image_params *imgp)
 	argv = *stack_base;
 	envp = *stack_base + (imgp->args->argc + 1);
 	(*stack_base)--;
-	**stack_base = (intptr_t)(void *)envp;
+	suword(*stack_base, (intptr_t)(void *)envp);
 	(*stack_base)--;
-	**stack_base = (intptr_t)(void *)argv;
+	suword(*stack_base, (intptr_t)(void *)argv);
 	(*stack_base)--;
-	**stack_base = imgp->args->argc;
+	suword(*stack_base, imgp->args->argc);
 	return (0);
 }
 
@@ -286,7 +286,7 @@ elf_linux_fixup(register_t **stack_base, struct image_params *imgp)
 	imgp->auxargs = NULL;
 
 	(*stack_base)--;
-	**stack_base = (register_t)imgp->args->argc;
+	suword(*stack_base, (register_t)imgp->args->argc);
 	return (0);
 }
 
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