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Mark the return address of the call to ast() in the generic trap

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handling code so the stack trace unwinders don't start trying to
go into user-space.

Found by trying to create core dumps with a KTR_COMPILE/KTR_GEOM
kernel, which results in a stack_save() call in the ast() coredump
path - this created a panic, and then calling 'trace' in ddb resulted
in the black screen of death after printing out most of the backtrace.
This commit is contained in:
Peter Grehan 2005-12-23 13:05:27 +00:00
parent 866196b69d
commit 78cb82148f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=153685
3 changed files with 13 additions and 5 deletions
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2
sys/powerpc/aim/trap_subr.S
View File

@ -438,6 +438,8 @@ CNAME(trapexit):
isync
addi %r3,%r1,8
bl CNAME(ast)
.globl CNAME(asttrapexit) /* backtrace code sentinel #2 */
CNAME(asttrapexit):
b trapexit /* test ast ret value ? */
1:
FRAME_LEAVE(PC_TEMPSAVE)

14
sys/powerpc/powerpc/db_trace.c
View File

@ -97,6 +97,7 @@ struct db_variable db_regs[] = {
struct db_variable *db_eregs = db_regs + sizeof (db_regs)/sizeof (db_regs[0]);
extern int trapexit[];
extern int asttrapexit[];
extern int end[];
/*
@ -186,11 +187,13 @@ db_backtrace(struct thread *td, db_addr_t fp, int count)
db_printf("0x%08x: ", stackframe);
/*
* The trap code labels the return address from the
* call to C code as 'trapexit'. Use this to determine
* if the callframe has to traverse a saved trap context
* The trap code labels the return addresses from the
* call to C code as 'trapexit' and 'asttrapexit. Use this
* to determine if the callframe has to traverse a saved
* trap context
*/
if (lr + 4 == (db_addr_t) &trapexit) {
if ((lr + 4 == (db_addr_t) &trapexit) ||
(lr + 4 == (db_addr_t) &asttrapexit)) {
const char *trapstr;
struct trapframe *tf = (struct trapframe *)
(stackframe+8);
@ -312,7 +315,8 @@ stack_save(struct stack *st)
* things are going wrong. Plus, prevents this shortened
* version of code from accessing user-space frames
*/
if (callpc + 4 == (db_addr_t) &trapexit)
if (callpc + 4 == (db_addr_t) &trapexit ||
callpc + 4 == (db_addr_t) &asttrapexit)
break;
if (stack_put(st, callpc) == -1)

2
sys/powerpc/powerpc/trap_subr.S
View File

@ -438,6 +438,8 @@ CNAME(trapexit):
isync
addi %r3,%r1,8
bl CNAME(ast)
.globl CNAME(asttrapexit) /* backtrace code sentinel #2 */
CNAME(asttrapexit):
b trapexit /* test ast ret value ? */
1:
FRAME_LEAVE(PC_TEMPSAVE)