On Thu, 20 Apr 2023, Finn Thain wrote:
I modified the test program to execute rec() to full depth with no
forking, then do it again with forking.
root@(none):/root# while ./stack-test 5000 ; do : ; done
starting recursion
done.
starting recursion with fork
done.
starting recursion
done.
starting recursion with fork
Illegal instruction
root@(none):/root#
I can't get this to crash during the first descent. The second descent
always crashes, given sufficient depth:
root@(none):/root# while ./stack-test 50000 ; do : ; done
starting recursion
done.
starting recursion with fork
Illegal instruction
So all the stack pages would have been faulted in well before the
failure shows up. It appears to be the signal that's the problem and not
the page fault.
Sorry, I was mistaken when I infered the absence of bus errors. I should
have enabled ignore_loglevel and checked the printk output from my patched
bus_error030():
# ./stack-test 5000
[ 47.430000] bus_error030: page fault: pc 80000642, addr 80072fe0
[ 47.440000] bus_error030: descriptor address 005a3dc8, contents 00000000
[ 47.460000] bus_error030: page fault: pc 8000064a, addr 8006ddc8
[ 47.470000] bus_error030: descriptor address 005a3db4, contents 011b300d
[ 47.750000] bus_error030: page fault: pc 8001a952, addr 80073068
[ 47.760000] bus_error030: descriptor address 005a3dcc, contents 00000000
[ 47.790000] bus_error030: page fault: pc 8001a99c, addr 8006fb14
[ 47.800000] bus_error030: descriptor address 005a3dbc, contents 011b800d
[ 47.880000] bus_error030: page fault: pc 80013e9e, addr 800744e0
[ 47.890000] bus_error030: descriptor address 005a3dd0, contents 00000000
[ 48.150000] bus_error030: page fault: pc 80038d14, addr efffee38
[ 48.160000] bus_error030: descriptor address 005a3bf8, contents 00000000
[ 48.600000] bus_error030: page fault: pc 80011d08, addr 80075adc
[ 48.620000] bus_error030: descriptor address 005a3dd4, contents 00000000
starting recursion
[ 48.650000] bus_error030: page fault: pc 8000038c, addr efffdffc
[ 48.660000] bus_error030: descriptor address 005a3bf4, contents 00000000
[ 48.670000] bus_error030: page fault: pc 8000038c, addr efffcffc
[ 48.690000] bus_error030: descriptor address 005a3bf0, contents 00000000
[ 48.710000] bus_error030: page fault: pc 8000038c, addr efffbffc
[ 48.720000] bus_error030: descriptor address 005a3bec, contents 00000000
[ 48.730000] bus_error030: page fault: pc 8000038c, addr efffaffc
[ 48.760000] bus_error030: descriptor address 005a3be8, contents 00000000
[ 48.770000] bus_error030: page fault: pc 8000038c, addr efff9ffc
[ 48.780000] bus_error030: descriptor address 005a3be4, contents 00000000
[ 48.790000] bus_error030: page fault: pc 80000388, addr efff8ffc
[ 48.820000] bus_error030: descriptor address 005a3be0, contents 00000000
[ 48.830000] bus_error030: page fault: pc 8000038c, addr efff7ffc
[ 48.840000] bus_error030: descriptor address 005a3bdc, contents 00000000
[ 48.850000] bus_error030: page fault: pc 8000038c, addr efff6ffc
[ 48.880000] bus_error030: descriptor address 005a3bd8, contents 00000000
[ 48.890000] bus_error030: page fault: pc 8000038c, addr efff5ffc
[ 48.900000] bus_error030: descriptor address 005a3bd4, contents 00000000
[ 48.920000] bus_error030: page fault: pc 8000038c, addr efff4ffc
[ 48.930000] bus_error030: descriptor address 005a3bd0, contents 00000000
[ 48.940000] bus_error030: page fault: pc 8000038c, addr efff3ffc
[ 48.950000] bus_error030: descriptor address 005a3bcc, contents 00000000
[ 48.970000] bus_error030: page fault: pc 8000038c, addr efff2ffc
[ 48.980000] bus_error030: descriptor address 005a3bc8, contents 00000000
[ 48.990000] bus_error030: page fault: pc 8000038c, addr efff1ffc
[ 49.000000] bus_error030: descriptor address 005a3bc4, contents 00000000
[ 49.020000] bus_error030: page fault: pc 8000038c, addr efff0ffc
[ 49.030000] bus_error030: descriptor address 005a3bc0, contents 00000000
[ 49.040000] bus_error030: page fault: pc 80000388, addr effefffc
[ 49.050000] bus_error030: descriptor address 005a3bbc, contents 00000000
[ 49.070000] bus_error030: page fault: pc 8000038c, addr effeeffc
[ 49.080000] bus_error030: descriptor address 005a3bb8, contents 00000000
[ 49.090000] bus_error030: page fault: pc 8000038c, addr effedffc
[ 49.100000] bus_error030: descriptor address 005a3bb4, contents 00000000
[ 49.120000] bus_error030: page fault: pc 8000038c, addr effecffc
[ 49.130000] bus_error030: descriptor address 005a3bb0, contents 00000000
[ 49.140000] bus_error030: page fault: pc 8000038c, addr effebffc
[ 49.150000] bus_error030: descriptor address 005a3bac, contents 00000000
[ 49.170000] bus_error030: page fault: pc 8000038c, addr effeaffc
[ 49.180000] bus_error030: descriptor address 005a3ba8, contents 00000000
[ 49.190000] bus_error030: page fault: pc 8000038c, addr effe9ffc
[ 49.200000] bus_error030: descriptor address 005a3ba4, contents 00000000
[ 49.220000] bus_error030: page fault: pc 8000038c, addr effe8ffc
[ 49.230000] bus_error030: descriptor address 005a3ba0, contents 00000000
[ 49.240000] bus_error030: page fault: pc 8000038c, addr effe7ffc
[ 49.250000] bus_error030: descriptor address 005a3b9c, contents 00000000
[ 49.270000] bus_error030: page fault: pc 80000388, addr effe6ffc
[ 49.280000] bus_error030: descriptor address 005a3b98, contents 00000000
[ 49.290000] bus_error030: page fault: pc 8000038c, addr effe5ffc
[ 49.300000] bus_error030: descriptor address 005a3b94, contents 00000000
[ 49.320000] bus_error030: page fault: pc 8000038c, addr effe4ffc
[ 49.330000] bus_error030: descriptor address 005a3b90, contents 00000000
[ 49.340000] bus_error030: page fault: pc 8000038c, addr effe3ffc
[ 49.360000] bus_error030: descriptor address 005a3b8c, contents 00000000
[ 49.380000] bus_error030: page fault: pc 8000038c, addr effe2ffc
[ 49.390000] bus_error030: descriptor address 005a3b88, contents 00000000
[ 49.400000] bus_error030: page fault: pc 8000038c, addr effe1ffc
[ 49.420000] bus_error030: descriptor address 005a3b84, contents 00000000
[ 49.440000] bus_error030: page fault: pc 8000038c, addr effe0ffc
[ 49.450000] bus_error030: descriptor address 005a3b80, contents 00000000
[ 49.460000] bus_error030: page fault: pc 8000038c, addr effdfffc
[ 49.490000] bus_error030: descriptor address 005a3b7c, contents 00000000
[ 49.500000] bus_error030: page fault: pc 8000038c, addr effdeffc
[ 49.510000] bus_error030: descriptor address 005a3b78, contents 00000000
[ 49.530000] bus_error030: page fault: pc 80000388, addr effddffc
[ 49.540000] bus_error030: descriptor address 005a3b74, contents 00000000
[ 49.550000] bus_error030: page fault: pc 8000038c, addr effdcffc
[ 49.560000] bus_error030: descriptor address 005a3b70, contents 00000000
[ 49.580000] bus_error030: page fault: pc 8000038c, addr effdbffc
[ 49.590000] bus_error030: descriptor address 005a3b6c, contents 00000000
[ 49.600000] bus_error030: page fault: pc 8000038c, addr effdaffc
[ 49.610000] bus_error030: descriptor address 005a3b68, contents 00000000
[ 49.630000] bus_error030: page fault: pc 8000038c, addr effd9ffc
[ 49.640000] bus_error030: descriptor address 005a3b64, contents 00000000
[ 49.650000] bus_error030: page fault: pc 8000038c, addr effd8ffc
[ 49.680000] bus_error030: descriptor address 005a3b60, contents 00000000
[ 49.690000] bus_error030: page fault: pc 8000038c, addr effd7ffc
[ 49.700000] bus_error030: descriptor address 005a3b5c, contents 00000000
[ 49.720000] bus_error030: page fault: pc 8000038c, addr effd6ffc
[ 49.730000] bus_error030: descriptor address 005a3b58, contents 00000000
[ 49.740000] bus_error030: page fault: pc 8000038c, addr effd5ffc
[ 49.750000] bus_error030: descriptor address 005a3b54, contents 00000000
[ 49.770000] bus_error030: page fault: pc 80000388, addr effd4ffc
[ 49.780000] bus_error030: descriptor address 005a3b50, contents 00000000
[ 49.800000] bus_error030: page fault: pc 8000038c, addr effd3ffc
[ 49.820000] bus_error030: descriptor address 005a3b4c, contents 00000000
done.
starting recursion with fork
[ 49.910000] bus_error030: page fault: pc 8001599c, addr efff7d3c
[ 49.930000] bus_error030: descriptor address 005a3bdc, contents 0182e01d
[ 49.940000] bus_error030: page fault: pc 80000b3c, addr efff7d24
[ 49.970000] bus_error030: descriptor address 014280dc, contents 0182e01d
[ 49.980000] bus_error030: page fault: pc 800003ea, addr 800703a0
[ 49.990000] bus_error030: descriptor address 005a3dc0, contents 011aa01d
[ 50.000000] bus_error030: page fault: pc 80015730, addr 800731d0
[ 50.030000] bus_error030: descriptor address 005a3fcc, contents 0132201d
[ 50.040000] bus_error030: page fault: pc 8000038c, addr efff6ffc
[ 50.050000] bus_error030: descriptor address 005a3bd8, contents 0182f01d
[ 50.070000] bus_error030: page fault: pc 8000038c, addr efff5ffc
[ 50.080000] bus_error030: descriptor address 005a3bd4, contents 0183001d
[ 50.090000] bus_error030: page fault: pc 80015736, addr 8006faf0
[ 50.100000] bus_error030: descriptor address 005a3fbc, contents 0132301d
[ 50.120000] bus_error030: page fault: pc 8000038c, addr efff4ffc
[ 50.130000] bus_error030: descriptor address 005a3bd0, contents 0183101d
[ 50.150000] bus_error030: page fault: pc 8000038c, addr efff3ffc
[ 50.160000] bus_error030: descriptor address 005a3bcc, contents 0183201d
[ 50.190000] bus_error030: page fault: pc 8000038c, addr efff2ffc
[ 50.200000] bus_error030: descriptor address 005a3bc8, contents 0183301d
[ 50.210000] bus_error030: page fault: pc 8000038c, addr efff1ffc
[ 50.240000] bus_error030: descriptor address 005a3bc4, contents 0183401d
[ 50.250000] bus_error030: page fault: pc 8000038c, addr efff0ffc
[ 50.260000] bus_error030: descriptor address 005a3bc0, contents 0183501d
[ 50.270000] bus_error030: page fault: pc 80000388, addr effefffc
[ 50.290000] bus_error030: descriptor address 005a3bbc, contents 0183601d
[ 50.310000] bus_error030: page fault: pc 8000038c, addr effeeffc
[ 50.320000] bus_error030: descriptor address 005a3bb8, contents 0183701d
[ 50.330000] bus_error030: page fault: pc 8000038c, addr effedffc
[ 50.360000] bus_error030: descriptor address 005a3bb4, contents 0183801d
[ 50.370000] bus_error030: page fault: pc 8000038c, addr effecffc
[ 50.380000] bus_error030: descriptor address 005a3bb0, contents 0183901d
[ 50.390000] bus_error030: page fault: pc 8000038c, addr effebffc
[ 50.420000] bus_error030: descriptor address 005a3bac, contents 0183a01d
[ 50.430000] bus_error030: page fault: pc 8000038c, addr effeaffc
[ 50.440000] bus_error030: descriptor address 005a3ba8, contents 0183b01d
[ 50.450000] bus_error030: page fault: pc 8000038c, addr effe9ffc
[ 50.480000] bus_error030: descriptor address 005a3ba4, contents 0183c01d
[ 50.490000] bus_error030: page fault: pc 8000038c, addr effe8ffc
[ 50.500000] bus_error030: descriptor address 005a3ba0, contents 0183d01d
[ 50.510000] bus_error030: page fault: pc 8000038c, addr effe7ffc
[ 50.530000] bus_error030: descriptor address 005a3b9c, contents 0183e01d
[ 50.550000] bus_error030: page fault: pc 80000388, addr effe6ffc
[ 50.560000] bus_error030: descriptor address 005a3b98, contents 0183f01d
[ 50.570000] bus_error030: page fault: pc 8000038c, addr effe5ffc
[ 50.590000] bus_error030: descriptor address 005a3b94, contents 0184001d
[ 50.620000] bus_error030: page fault: pc 8001599c, addr effe5d3c
[ 50.630000] bus_error030: descriptor address 005a3b94, contents 0184001d
[ 50.650000] bus_error030: page fault: pc 80000b3c, addr effe5d24
[ 50.660000] bus_error030: descriptor address 01429094, contents 0184001d
[ 50.670000] bus_error030: page fault: pc 800003ea, addr 800703a0
[ 50.680000] bus_error030: descriptor address 005a3dc0, contents 0185501d
[ 50.700000] bus_error030: page fault: pc 80015730, addr 800731d0
[ 50.710000] bus_error030: descriptor address 005a3fcc, contents 0132201d
[ 50.720000] bus_error030: page fault: pc 8000038c, addr effe4ffc
[ 50.730000] bus_error030: descriptor address 005a3b90, contents 0184101d
[ 50.750000] bus_error030: page fault: pc 80015736, addr 8006faf0
[ 50.760000] bus_error030: descriptor address 005a3fbc, contents 0132301d
[ 50.780000] bus_error030: page fault: pc 8000038c, addr effe3ffc
[ 50.790000] bus_error030: descriptor address 005a3b8c, contents 0184201d
[ 50.820000] bus_error030: page fault: pc 8000038c, addr effe2ffc
[ 50.830000] bus_error030: descriptor address 005a3b88, contents 0184301d
[ 50.840000] bus_error030: page fault: pc 8000038c, addr effe1ffc
[ 50.860000] bus_error030: descriptor address 005a3b84, contents 0184401d
[ 50.880000] bus_error030: page fault: pc 8000038c, addr effe0ffc
[ 50.890000] bus_error030: descriptor address 005a3b80, contents 0184501d
[ 50.900000] bus_error030: page fault: pc 8000038c, addr effdfffc
[ 50.920000] bus_error030: descriptor address 005a3b7c, contents 0184601d
[ 50.940000] bus_error030: page fault: pc 8000038c, addr effdeffc
[ 50.950000] bus_error030: descriptor address 005a3b78, contents 0184701d
[ 50.960000] bus_error030: page fault: pc 80000388, addr effddffc
[ 50.990000] bus_error030: descriptor address 005a3b74, contents 0184801d
[ 51.000000] bus_error030: page fault: pc 8000038c, addr effdcffc
[ 51.010000] bus_error030: descriptor address 005a3b70, contents 0184901d
[ 51.030000] bus_error030: page fault: pc 8000038c, addr effdbffc
[ 51.040000] bus_error030: descriptor address 005a3b6c, contents 0184a01d
[ 51.050000] bus_error030: page fault: pc 8000038c, addr effdaffc
[ 51.060000] bus_error030: descriptor address 005a3b68, contents 0184b01d
[ 51.070000] bus_error030: page fault: pc 8000038c, addr effd9ffc
[ 51.100000] bus_error030: descriptor address 005a3b64, contents 0184c01d
[ 51.110000] bus_error030: page fault: pc 8000038c, addr effd8ffc
[ 51.120000] bus_error030: descriptor address 005a3b60, contents 0184d01d
[ 51.130000] bus_error030: page fault: pc 8000038c, addr effd7ffc
[ 51.160000] bus_error030: descriptor address 005a3b5c, contents 0184e01d
[ 51.170000] bus_error030: page fault: pc 8000038c, addr effd6ffc
[ 51.180000] bus_error030: descriptor address 005a3b58, contents 0184f01d
[ 51.190000] bus_error030: page fault: pc 8000038c, addr effd5ffc
[ 51.220000] bus_error030: descriptor address 005a3b54, contents 0185001d
[ 51.230000] bus_error030: page fault: pc 80000388, addr effd4ffc
[ 51.240000] bus_error030: descriptor address 005a3b50, contents 0185101d
[ 51.260000] bus_error030: page fault: pc 8000038c, addr effd3ffc
[ 51.270000] bus_error030: descriptor address 005a3b4c, contents 0185201d
[ 51.290000] bus_error030: page fault: pc 8001599c, addr effd3d3c
[ 51.300000] bus_error030: descriptor address 005a3b4c, contents 0185201d
[ 51.320000] bus_error030: page fault: pc 80000b3c, addr effd3d24
[ 51.330000] bus_error030: descriptor address 0142804c, contents 0185201d
[ 51.340000] bus_error030: page fault: pc 800003ea, addr 800703a0
[ 51.360000] bus_error030: descriptor address 005a3dc0, contents 0185601d
[ 51.380000] bus_error030: page fault: pc 80015730, addr 800731d0
[ 51.390000] bus_error030: descriptor address 005a3fcc, contents 0132201d
[ 51.400000] bus_error030: page fault: pc 80015736, addr 8006faf0
[ 51.430000] bus_error030: descriptor address 005a3fbc, contents 0132301d
Illegal instruction
#
diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index a700807c9b6d..4820d5e7dd8d 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -500,9 +500,7 @@ static inline void bus_error030 (struct frame *fp)
unsigned short mmusr;
unsigned long addr, errorcode;
unsigned short ssw = fp->un.fmtb.ssw;
-#ifdef DEBUG
unsigned long desc;
-#endif
pr_debug("pid = %x ", current->pid);
pr_debug("SSW=%#06x ", ssw);
@@ -526,25 +524,24 @@ static inline void bus_error030 (struct frame *fp)
if (ssw & DF) {
addr = fp->un.fmtb.daddr;
-#ifdef DEBUG
asm volatile ("ptestr %3,%2@,#7,%0\n\t"
"pmove %%psr,%1"
: "=a&" (desc), "=m" (temp)
: "a" (addr), "d" (ssw));
- pr_debug("mmusr is %#x for addr %#lx in task %p\n",
- temp, addr, current);
- pr_debug("descriptor address is 0x%p, contents %#lx\n",
- __va(desc), *(unsigned long *)__va(desc));
-#else
- asm volatile ("ptestr %2,%1@,#7\n\t"
- "pmove %%psr,%0"
- : "=m" (temp) : "a" (addr), "d" (ssw));
-#endif
mmusr = temp;
errorcode = (mmusr & MMU_I) ? 0 : 1;
if (!(ssw & RW) || (ssw & RM))
errorcode |= 2;
+ if ((ssw & RW) == 0) {
+ u16 inst;
+ if (get_user(inst, (u16 *)fp->ptregs.pc) == 0 &&
+ memcmp(current->comm, "stack-test", 10) == 0) {
+ printk(KERN_DEBUG "%s: page fault: pc %08lx, addr %08lx\n", __func__, fp->ptregs.pc, addr);
+ printk(KERN_DEBUG "%s: descriptor address %08lx, contents %08lx\n", __func__, (unsigned long)__va(desc), *(unsigned long *)__va(desc));
+ }
+ }
+
if (mmusr & (MMU_I | MMU_WP)) {
/* We might have an exception table for this PC */
if (ssw & 4 && !search_exception_tables(fp->ptregs.pc)) {
