From b344e24a8e8ceda83d1285d22e3e5baf4f5e42d3 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Sun, 16 Aug 2009 21:54:48 +0100 Subject: sh: unwinder: Introduce UNWINDER_BUG() and UNWINDER_BUG_ON() We can't assume that if we execute the unwinder code and the unwinder was already running that it has faulted. Clearly two kernel threads can invoke the unwinder at the same time and may be running simultaneously. The previous approach used BUG() and BUG_ON() in the unwinder code to detect whether the unwinder was incapable of unwinding the stack, and that the next available unwinder should be used instead. A better approach is to explicitly invoke a trap handler to switch unwinders when the current unwinder cannot continue. Signed-off-by: Matt Fleming --- arch/sh/kernel/traps.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'arch/sh/kernel/traps.c') diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c index b3e0067db358..881b9a32b7de 100644 --- a/arch/sh/kernel/traps.c +++ b/arch/sh/kernel/traps.c @@ -8,7 +8,7 @@ #include #ifdef CONFIG_BUG -static void handle_BUG(struct pt_regs *regs) +void handle_BUG(struct pt_regs *regs) { enum bug_trap_type tt; tt = report_bug(regs->pc, regs); @@ -29,7 +29,10 @@ int is_valid_bugaddr(unsigned long addr) if (probe_kernel_address((insn_size_t *)addr, opcode)) return 0; - return opcode == TRAPA_BUG_OPCODE; + if (opcode == TRAPA_BUG_OPCODE || opcode == TRAPA_UNWINDER_BUG_OPCODE) + return 1; + + return 0; } #endif -- cgit v1.2.1 From e115f2c17cbceee93b34d787a7a4a867fc73e7b4 Mon Sep 17 00:00:00 2001 From: Paul Mundt Date: Sat, 22 Aug 2009 05:28:25 +0900 Subject: sh: unwinder: Use a special bug flag for unwinder traps. This simplifies the unwinder trap handling, dropping the use of the special trapa vector and simply piggybacking on top of the BUG support. A new BUGFLAG_UNWINDER is added for flagging the unwinder fault, before continuing on with regular BUG dispatch. Signed-off-by: Paul Mundt --- arch/sh/kernel/traps.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'arch/sh/kernel/traps.c') diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c index 881b9a32b7de..f69bd968fcca 100644 --- a/arch/sh/kernel/traps.c +++ b/arch/sh/kernel/traps.c @@ -5,18 +5,32 @@ #include #include #include +#include #include #ifdef CONFIG_BUG void handle_BUG(struct pt_regs *regs) { + const struct bug_entry *bug; + unsigned long bugaddr = regs->pc; enum bug_trap_type tt; - tt = report_bug(regs->pc, regs); + + if (!is_valid_bugaddr(bugaddr)) + goto invalid; + + bug = find_bug(bugaddr); + + /* Switch unwinders when unwind_stack() is called */ + if (bug->flags & BUGFLAG_UNWINDER) + unwinder_faulted = 1; + + tt = report_bug(bugaddr, regs); if (tt == BUG_TRAP_TYPE_WARN) { - regs->pc += instruction_size(regs->pc); + regs->pc += instruction_size(bugaddr); return; } +invalid: die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff); } @@ -28,8 +42,7 @@ int is_valid_bugaddr(unsigned long addr) return 0; if (probe_kernel_address((insn_size_t *)addr, opcode)) return 0; - - if (opcode == TRAPA_BUG_OPCODE || opcode == TRAPA_UNWINDER_BUG_OPCODE) + if (opcode == TRAPA_BUG_OPCODE) return 1; return 0; -- cgit v1.2.1