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- Properly unwind stack for functions with __noreturn__ attribute

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Submitted by:	Neelkanth Natu <neelnatu@yahoo.com>
This commit is contained in:
Oleksandr Tymoshenko 2009-07-30 23:48:29 +00:00
parent 1367982697
commit 13a77922c8
1 changed files with 33 additions and 4 deletions
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37
sys/mips/mips/trap.c
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@ -1229,8 +1229,25 @@ MipsEmulateBranch(struct trapframe *framePtr, int instPC, int fpcCSR,
#if defined(DDB) || defined(DEBUG)
#define MIPS_JR_RA 0x03e00008 /* instruction code for jr ra */
/*
* A function using a stack frame has the following instruction as the first
* one: addiu sp,sp,-<frame_size>
*
* We make use of this to detect starting address of a function. This works
* better than using 'j ra' instruction to signify end of the previous
* function (for e.g. functions like boot() or panic() do not actually
* emit a 'j ra' instruction).
*
* XXX the abi does not require that the addiu instruction be the first one.
*/
#define MIPS_START_OF_FUNCTION(ins) (((ins) & 0xffff8000) == 0x27bd8000)
/*
* MIPS ABI 3.0 requires that all functions return using the 'j ra' instruction
*
* XXX gcc doesn't do this true for functions with __noreturn__ attribute.
*/
#define MIPS_END_OF_FUNCTION(ins) ((ins) == 0x03e00008)
/* forward */
char *fn_name(unsigned addr);
@ -1326,9 +1343,21 @@ loop:
*/
if (!subr) {
va = pc - sizeof(int);
while ((instr = kdbpeek((int *)va)) != MIPS_JR_RA)
va -= sizeof(int);
va += 2 * sizeof(int); /* skip back over branch & delay slot */
while (1) {
instr = kdbpeek((int *)va);
if (MIPS_START_OF_FUNCTION(instr))
break;
if (MIPS_END_OF_FUNCTION(instr)) {
/* skip over branch-delay slot instruction */
va += 2 * sizeof(int);
break;
}
va -= sizeof(int);
}
/* skip over nulls which might separate .o files */
while ((instr = kdbpeek((int *)va)) == 0)
va += sizeof(int);