__tls_get_addr problem with recent current
Kostik Belousov
kostikbel at gmail.com
Sun Aug 31 09:16:53 UTC 2008
On Sun, Aug 31, 2008 at 10:16:18AM +0300, Kostik Belousov wrote:
> On Sat, Aug 30, 2008 at 02:03:00PM -0700, Artem Belevich wrote:
> > With the new patch kernel has crashed as soon as I ran i386 app,
> > though the crash happened within in-kernel thread g_up:
> >
> > Fatal trap 12: page fault while in kernel mode
> > cpuid = 2; apic id = 02
> > fault virtual address = 0x20
> > fault code = supervisor read data, page not present
> > instruction pointer = 0x8:0xffffffff804a821f
> > stack pointer = 0x10:0xffffffffac280b60
> > frame pointer = 0x10:0x0
> > code segment = base 0x0, limit 0xfffff, type 0x1b
> > = DPL 0, pres 1, long 1, def32 0, gran 1
> > processor eflags = resume, IOPL = 0
> > current process = 3 (g_up)
> > trap number = 12
> > panic: page fault
> > cpuid = 2
> > Uptime: 37s
> > Physical memory: 8169 MB
> > Dumping 380 MB: 365 349 333 317 301 285 269 253 237 221 205 189 173
> > 157 141 125 109 93 77 61 45 29 13
> Could you, please, show me the disassembled code around the faulted
> %rip ?
No need, it seems I found the problem. I trashed the %rdx that contains
the third cpu_switch argument. Please, try the updated patch.
Thanks for the testing !
diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index f34b0cc..03f0eca 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -249,6 +249,12 @@ store_seg:
1: movl %ds,PCB_DS(%r8)
movl %es,PCB_ES(%r8)
movl %fs,PCB_FS(%r8)
+ movq %rdx,%r11
+ movl $MSR_FSBASE,%ecx
+ rdmsr
+ shlq $32,%rdx
+ leaq (%rax,%rdx),%r9
+ movq %r11,%rdx
jmp done_store_seg
2: movq PCB_GS32P(%r8),%rax
movq (%rax),%rax
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