From f5a16b93e6291ba1f65f55647cb4cd8d75ed1b35 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Wed, 20 Dec 2017 12:37:54 -0800 Subject: [PATCH] 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 --- 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 bcd7c9f..004f4e4 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 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 7d8c1d6..6e9a0a9 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