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 correspondingly which this
patch handles. If user mode, the task is terminated with a SEGV, for
kernel mode die() called after register and stack dump.
Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
---
arch/arc/kernel/traps.c | 6 ++++++
arch/arc/kernel/troubleshoot.c | 3 +++
2 files changed, 9 insertions(+)
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index bcd7c9fc5d0f..004f4e4a4c10 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -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;
}
diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c
index 7d8c1d6c2f60..6e9a0a9a6a04 100644
--- a/arch/arc/kernel/troubleshoot.c
+++ b/arch/arc/kernel/troubleshoot.c
@@ -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");
}
--
2.7.4
