forked from luck/tmp_suning_uos_patched
ef3e035c3a
Meelis Roos reported that kernels built with gcc-4.9 do not boot, we eventually narrowed this down to only impacting machines using UltraSPARC-III and derivitive cpus. The crash happens right when the first user process is spawned: [ 54.451346] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 [ 54.451346] [ 54.571516] CPU: 1 PID: 1 Comm: init Not tainted 3.16.0-rc2-00211-gd7933ab #96 [ 54.666431] Call Trace: [ 54.698453] [0000000000762f8c] panic+0xb0/0x224 [ 54.759071] [000000000045cf68] do_exit+0x948/0x960 [ 54.823123] [000000000042cbc0] fault_in_user_windows+0xe0/0x100 [ 54.902036] [0000000000404ad0] __handle_user_windows+0x0/0x10 [ 54.978662] Press Stop-A (L1-A) to return to the boot prom [ 55.050713] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 Further investigation showed that compiling only per_cpu_patch() with an older compiler fixes the boot. Detailed analysis showed that the function is not being miscompiled by gcc-4.9, but it is using a different register allocation ordering. With the gcc-4.9 compiled function, something during the code patching causes some of the %i* input registers to get corrupted. Perhaps we have a TLB miss path into the firmware that is deep enough to cause a register window spill and subsequent restore when we get back from the TLB miss trap. Let's plug this up by doing two things: 1) Stop using the firmware stack for client interface calls into the firmware. Just use the kernel's stack. 2) As soon as we can, call into a new function "start_early_boot()" to put a one-register-window buffer between the firmware's deepest stack frame and the top-most initial kernel one. Reported-by: Meelis Roos <mroos@linux.ee> Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: David S. Miller <davem@davemloft.net>
137 lines
2.6 KiB
ArmAsm
137 lines
2.6 KiB
ArmAsm
/* hvtramp.S: Hypervisor start-cpu trampoline code.
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*
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* Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>
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*/
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#include <asm/thread_info.h>
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#include <asm/hypervisor.h>
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#include <asm/scratchpad.h>
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#include <asm/spitfire.h>
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#include <asm/hvtramp.h>
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#include <asm/pstate.h>
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#include <asm/ptrace.h>
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#include <asm/head.h>
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#include <asm/asi.h>
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#include <asm/pil.h>
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.align 8
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.globl hv_cpu_startup, hv_cpu_startup_end
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/* This code executes directly out of the hypervisor
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* with physical addressing (va==pa). %o0 contains
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* our client argument which for Linux points to
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* a descriptor data structure which defines the
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* MMU entries we need to load up.
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*
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* After we set things up we enable the MMU and call
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* into the kernel.
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*
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* First setup basic privileged cpu state.
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*/
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hv_cpu_startup:
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SET_GL(0)
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wrpr %g0, PIL_NORMAL_MAX, %pil
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wrpr %g0, 0, %canrestore
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wrpr %g0, 0, %otherwin
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wrpr %g0, 6, %cansave
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wrpr %g0, 6, %cleanwin
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wrpr %g0, 0, %cwp
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wrpr %g0, 0, %wstate
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wrpr %g0, 0, %tl
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sethi %hi(sparc64_ttable_tl0), %g1
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wrpr %g1, %tba
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mov %o0, %l0
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lduw [%l0 + HVTRAMP_DESCR_CPU], %g1
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mov SCRATCHPAD_CPUID, %g2
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stxa %g1, [%g2] ASI_SCRATCHPAD
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ldx [%l0 + HVTRAMP_DESCR_FAULT_INFO_VA], %g2
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stxa %g2, [%g0] ASI_SCRATCHPAD
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mov 0, %l1
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lduw [%l0 + HVTRAMP_DESCR_NUM_MAPPINGS], %l2
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add %l0, HVTRAMP_DESCR_MAPS, %l3
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1: ldx [%l3 + HVTRAMP_MAPPING_VADDR], %o0
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clr %o1
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ldx [%l3 + HVTRAMP_MAPPING_TTE], %o2
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mov HV_MMU_IMMU | HV_MMU_DMMU, %o3
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mov HV_FAST_MMU_MAP_PERM_ADDR, %o5
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ta HV_FAST_TRAP
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brnz,pn %o0, 80f
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nop
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add %l1, 1, %l1
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cmp %l1, %l2
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blt,a,pt %xcc, 1b
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add %l3, HVTRAMP_MAPPING_SIZE, %l3
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ldx [%l0 + HVTRAMP_DESCR_FAULT_INFO_PA], %o0
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mov HV_FAST_MMU_FAULT_AREA_CONF, %o5
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ta HV_FAST_TRAP
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brnz,pn %o0, 80f
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nop
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wrpr %g0, (PSTATE_PRIV | PSTATE_PEF), %pstate
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ldx [%l0 + HVTRAMP_DESCR_THREAD_REG], %l6
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mov 1, %o0
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set 1f, %o1
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mov HV_FAST_MMU_ENABLE, %o5
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ta HV_FAST_TRAP
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ba,pt %xcc, 80f
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nop
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1:
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wr %g0, 0, %fprs
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wr %g0, ASI_P, %asi
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mov PRIMARY_CONTEXT, %g7
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stxa %g0, [%g7] ASI_MMU
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membar #Sync
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mov SECONDARY_CONTEXT, %g7
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stxa %g0, [%g7] ASI_MMU
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membar #Sync
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mov %l6, %g6
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ldx [%g6 + TI_TASK], %g4
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mov 1, %g5
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sllx %g5, THREAD_SHIFT, %g5
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sub %g5, (STACKFRAME_SZ + STACK_BIAS), %g5
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add %g6, %g5, %sp
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call init_irqwork_curcpu
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nop
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call hard_smp_processor_id
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nop
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call sun4v_register_mondo_queues
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nop
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call init_cur_cpu_trap
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mov %g6, %o0
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wrpr %g0, (PSTATE_PRIV | PSTATE_PEF | PSTATE_IE), %pstate
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call smp_callin
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nop
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call cpu_panic
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nop
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80: ba,pt %xcc, 80b
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nop
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.align 8
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hv_cpu_startup_end:
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