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ARC: handle gcc generated __builtin_trap() 

gcc toggle -fisolate-erroneous-paths-dereference (default at -O2
onwards) isolates faulty code paths such as null pointer access, divide
by zero etc by emitting __builtin_trap()

Newer ARC gcc generates TRAP_S 5 instruction which needs to be handled
and treated like any other unexpected exception
  - user mode  : task terminated with a SEGV
  - kernel mode: die() called after register and stack dump

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2017-12-20 12:37:54 -08:00
parent 79435ac78d
commit f5a16b93e6
2 changed files with 9 additions and 0 deletions
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6
arch/arc/kernel/traps.c
View File

@ -83,6 +83,7 @@ DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
/*
* Entry Point for Misaligned Data access Exception, for emulating in software
@ -115,6 +116,8 @@ void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
* Thus TRAP_S <n> can be used for specific purpose
* -1 used for software breakpointing (gdb)
* -2 used by kprobes
* -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
* -fno-isolate-erroneous-paths-dereference
*/
void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
{
@ -134,6 +137,9 @@ void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
kgdb_trap(regs);
break;
case 5:
do_trap5_error(address, regs);
break;
default:
break;
}

3
arch/arc/kernel/troubleshoot.c
View File

@ -163,6 +163,9 @@ static void show_ecr_verbose(struct pt_regs *regs)
else
pr_cont("Bus Error, check PRM\n");
#endif
} else if (vec == ECR_V_TRAP) {
if (regs->ecr_param == 5)
pr_cont("gcc generated __builtin_trap\n");
} else {
pr_cont("Check Programmer's Manual\n");
}