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| author | Will Deacon <will.deacon@arm.com> | 2016-02-10 17:05:28 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-02-10 17:05:28 +0100 |
| commit | e04a28d45ff343b47a4ffc4dee3a3e279e76ddfa (patch) | |
| tree | 0122e91fd0d3d506298658f7b7dbeced83b69bc3 /arch | |
| parent | arm64: disable kasan when accessing frame->fp in unwind_frame (diff) | |
| download | linux-e04a28d45ff343b47a4ffc4dee3a3e279e76ddfa.tar.xz linux-e04a28d45ff343b47a4ffc4dee3a3e279e76ddfa.zip | |
arm64: debug: re-enable irqs before sending breakpoint SIGTRAP
force_sig_info can sleep under an -rt kernel, so attempting to send a
breakpoint SIGTRAP with interrupts disabled yields the following BUG:
BUG: sleeping function called from invalid context at
/kernel-source/kernel/locking/rtmutex.c:917
in_atomic(): 0, irqs_disabled(): 128, pid: 551, name: test.sh
CPU: 5 PID: 551 Comm: test.sh Not tainted 4.1.13-rt13 #7
Hardware name: Freescale Layerscape 2085a RDB Board (DT)
Call trace:
dump_backtrace+0x0/0x128
show_stack+0x24/0x30
dump_stack+0x80/0xa0
___might_sleep+0x128/0x1a0
rt_spin_lock+0x2c/0x40
force_sig_info+0xcc/0x210
brk_handler.part.2+0x6c/0x80
brk_handler+0xd8/0xe8
do_debug_exception+0x58/0xb8
This patch fixes the problem by ensuring that interrupts are enabled
prior to sending the SIGTRAP if they were already enabled in the user
context.
Reported-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/debug-monitors.c | 48 |
1 files changed, 22 insertions, 26 deletions
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 8aee3aeec3e6..c536c9e307b9 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -226,11 +226,28 @@ static int call_step_hook(struct pt_regs *regs, unsigned int esr) return retval; } +static void send_user_sigtrap(int si_code) +{ + struct pt_regs *regs = current_pt_regs(); + siginfo_t info = { + .si_signo = SIGTRAP, + .si_errno = 0, + .si_code = si_code, + .si_addr = (void __user *)instruction_pointer(regs), + }; + + if (WARN_ON(!user_mode(regs))) + return; + + if (interrupts_enabled(regs)) + local_irq_enable(); + + force_sig_info(SIGTRAP, &info, current); +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { - siginfo_t info; - /* * If we are stepping a pending breakpoint, call the hw_breakpoint * handler first. @@ -239,11 +256,7 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; if (user_mode(regs)) { - info.si_signo = SIGTRAP; - info.si_errno = 0; - info.si_code = TRAP_HWBKPT; - info.si_addr = (void __user *)instruction_pointer(regs); - force_sig_info(SIGTRAP, &info, current); + send_user_sigtrap(TRAP_HWBKPT); /* * ptrace will disable single step unless explicitly @@ -307,17 +320,8 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr) static int brk_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { - siginfo_t info; - if (user_mode(regs)) { - info = (siginfo_t) { - .si_signo = SIGTRAP, - .si_errno = 0, - .si_code = TRAP_BRKPT, - .si_addr = (void __user *)instruction_pointer(regs), - }; - - force_sig_info(SIGTRAP, &info, current); + send_user_sigtrap(TRAP_BRKPT); } else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { pr_warning("Unexpected kernel BRK exception at EL1\n"); return -EFAULT; @@ -328,7 +332,6 @@ static int brk_handler(unsigned long addr, unsigned int esr, int aarch32_break_handler(struct pt_regs *regs) { - siginfo_t info; u32 arm_instr; u16 thumb_instr; bool bp = false; @@ -359,14 +362,7 @@ int aarch32_break_handler(struct pt_regs *regs) if (!bp) return -EFAULT; - info = (siginfo_t) { - .si_signo = SIGTRAP, - .si_errno = 0, - .si_code = TRAP_BRKPT, - .si_addr = pc, - }; - - force_sig_info(SIGTRAP, &info, current); + send_user_sigtrap(TRAP_BRKPT); return 0; } |