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For non-profiling kernels, there were two symbols assigned to the same

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address.  One was alltraps_with_regs_pushed, the other was calltrap.

When the stack tracer walks up, it looks for magic symbol names to
determine how to parse non-standard stack frames, such as a trapframe.
It was looking for "calltrap".  Which of the two symbols you got depended
on things like Phase of moon, etc.  If you were unlucky, you got a
garbage stack trace for things like 'debug.trace_on_panic', which would
completely hide the actual source of the problem.
This commit is contained in:
peter 2005-05-21 00:02:12 +00:00
parent b10ae11bf9
commit 591c5c4045
1 changed files with 4 additions and 2 deletions
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6
sys/amd64/amd64/exception.S
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@ -165,8 +165,9 @@ alltraps_pushregs_no_rdi:
movq %r13,TF_R13(%rsp)
movq %r14,TF_R14(%rsp)
movq %r15,TF_R15(%rsp)
alltraps_with_regs_pushed:
FAKE_MCOUNT(TF_RIP(%rsp))
.globl calltrap
.type calltrap,@function
calltrap:
call trap
MEXITCOUNT
@ -434,4 +435,5 @@ doreti_iret_fault:
movq %r15,TF_R15(%rsp)
movq $T_PROTFLT,TF_TRAPNO(%rsp)
movq $0,TF_ERR(%rsp) /* XXX should be the error code */
jmp alltraps_with_regs_pushed
FAKE_MCOUNT(TF_RIP(%rsp))
jmp calltrap