linux-toradex.git/arch/powerpc/kernel/misc_32.S, branch v3.14.57

powerpc: Set the correct ksp_limit on ppc32 when switching to irq stack

2014-02-17T00:19:34+00:00

Guenter Roeck has got the following call trace on a p2020 board:
  Kernel stack overflow in process eb3e5a00, r1=eb79df90
  CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
  task: eb3e5a00 ti: c0616000 task.ti: ef440000
  NIP: c003a420 LR: c003a410 CTR: c0017518
  REGS: eb79dee0 TRAP: 0901   Not tainted (3.13.0-rc8-juniper-00146-g19eca00)
  MSR: 00029000   CR: 24008444  XER: 00000000
  GPR00: c003a410 eb79df90 eb3e5a00 00000000 eb05d900 00000001 65d87646 00000000
  GPR08: 00000000 020b8000 00000000 00000000 44008442
  NIP [c003a420] __do_softirq+0x94/0x1ec
  LR [c003a410] __do_softirq+0x84/0x1ec
  Call Trace:
  [eb79df90] [c003a410] __do_softirq+0x84/0x1ec (unreliable)
  [eb79dfe0] [c003a970] irq_exit+0xbc/0xc8
  [eb79dff0] [c000cc1c] call_do_irq+0x24/0x3c
  [ef441f20] [c00046a8] do_IRQ+0x8c/0xf8
  [ef441f40] [c000e7f4] ret_from_except+0x0/0x18
  --- Exception: 501 at 0xfcda524
      LR = 0x10024900
  Instruction dump:
  7c781b78 3b40000a 3a73b040 543c0024 3a800000 3b3913a0 7ef5bb78 48201bf9
  5463103a 7d3b182e 7e89b92e 7c008146 <3ba00000> 7e7e9b78 48000014 57fff87f
  Kernel panic - not syncing: kernel stack overflow
  CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
  Call Trace:

The reason is that we have used the wrong register to calculate the
ksp_limit in commit cbc9565ee826 (powerpc: Remove ksp_limit on ppc64).
Just fix it.

As suggested by Benjamin Herrenschmidt, also add the C prototype of the
function in the comment in order to avoid such kind of errors in the
future.

Cc: stable@vger.kernel.org # 3.12
Reported-by: Guenter Roeck 
Tested-by: Guenter Roeck 
Signed-off-by: Kevin Hao 
Signed-off-by: Benjamin Herrenschmidt

powerpc: purge all the prefetched instructions for the coherent icache flush

2013-12-02T03:13:47+00:00

As Benjamin Herrenschmidt has indicated, we still need a dummy icbi to
purge all the prefetched instructions from the ifetch buffers for the
snooping icache. We also need a sync before the icbi to order the
actual stores to memory that might have modified instructions with
the icbi.

Signed-off-by: Kevin Hao 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Added __cmpdi2 for signed 64bit comparision

2013-10-11T05:49:27+00:00

This was missing on powerpc and I am getting compilation error
drivers/vfio/pci/vfio_pci_rdwr.c:193: undefined reference to `__cmpdi2'
drivers/vfio/pci/vfio_pci_rdwr.c:193: undefined reference to `__cmpdi2'

Signed-off-by: Bharat Bhushan 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove ksp_limit on ppc64

2013-09-25T04:15:51+00:00

We've been keeping that field in thread_struct for a while, it contains
the "limit" of the current stack pointer and is meant to be used for
detecting stack overflows.

It has a few problems however:

 - First, it was never actually *used* on 64-bit. Set and updated but
not actually exploited

 - When switching stack to/from irq and softirq stacks, it's update
is racy unless we hard disable interrupts, which is costly. This
is fine on 32-bit as we don't soft-disable there but not on 64-bit.

Thus rather than fixing 2 in order to implement 1 in some hypothetical
future, let's remove the code completely from 64-bit. In order to avoid
a clutter of ifdef's, we remove the updates from C code completely
during interrupt stack switching, and instead maintain it from the
asm helper that is used to do the stack switching in the first place.

Signed-off-by: Benjamin Herrenschmidt

powerpc/irq: Run softirqs off the top of the irq stack

2013-09-25T04:15:36+00:00

Nowadays, irq_exit() calls __do_softirq() pretty much directly
instead of calling do_softirq() which switches to the decicated
softirq stack.

This has lead to observed stack overflows on powerpc since we call
irq_enter() and irq_exit() outside of the scope that switches to
the irq stack.

This fixes it by moving the stack switching up a level, making
irq_enter() and irq_exit() run off the irq stack.

Signed-off-by: Benjamin Herrenschmidt

powerpc: Remove the symbol __flush_icache_range

2013-08-14T04:56:44+00:00

And now the function flush_icache_range() is just a wrapper which
only invoke the function __flush_icache_range() directly. So we
don't have reason to keep it anymore.

Signed-off-by: Kevin Hao 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Move the testing of CPU_FTR_COHERENT_ICACHE into __flush_icache_range

2013-08-14T04:56:06+00:00

In function flush_icache_range(), we use cpu_has_feature() to test
the feature bit of CPU_FTR_COHERENT_ICACHE. But this seems not optimal
for two reasons:
 a) For ppc32, the function __flush_icache_range() already do this
    check with the macro END_FTR_SECTION_IFSET.
 b) Compare with the cpu_has_feature(), the method of using macro
    END_FTR_SECTION_IFSET will not introduce any runtime overhead.

[And while at it, add the missing required isync] -- BenH

Signed-off-by: Kevin Hao 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Provide __bswapdi2

2013-05-14T06:00:17+00:00

Some versions of GCC apparently expect this to be provided by libgcc.

Updates from Mikey to fix 32 bit version and adding "r" to registers.

Signed-off-by: David Woodhouse 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: split ret_from_fork

2012-10-01T03:31:19+00:00

... and get rid of in-kernel syscalls in kernel_thread()

Signed-off-by: Al Viro

powerpc: Use CURRENT_THREAD_INFO instead of open coded assembly

2012-07-11T04:18:22+00:00

Signed-off-by: Stuart Yoder 
Signed-off-by: Benjamin Herrenschmidt