[PATCH v3 16/20] bsd-user: Implement SIGSYS on arm

[Warner Losh <imp@bsdimp.com>]

When a system call returns ENOSYS, send a SIGSYS to the process (to
generate a core dump).

Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 bsd-user/arm/target_arch_cpu.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/bsd-user/arm/target_arch_cpu.h b/bsd-user/arm/target_arch_cpu.h
index 517d0087644..c4b21fef713 100644
--- a/bsd-user/arm/target_arch_cpu.h
+++ b/bsd-user/arm/target_arch_cpu.h
@@ -127,6 +127,14 @@ static inline void target_cpu_loop(CPUARMState *env)
                     env->regs[15] -= env->thumb ? 2 : 4;
                     break;
                 }
+                /*
+                 * Emulate BSD's sigsys behavior on unimplemented system calls.
+                 * XXX may need to gate this somehow or arrange for sigsys to be
+                 * masked in some use cases.
+                 */
+                if (ret == -TARGET_ENOSYS) {
+                    force_sig_fault(TARGET_SIGSYS, SI_KERNEL, env->regs[15]);
+                }
                 if ((unsigned int)ret >= (unsigned int)(-515)) {
                     ret = -ret;
                     cpsr_write(env, CPSR_C, CPSR_C, CPSRWriteByInstr);
-- 
2.40.0