diff mbox series

[PULL,3/7] linux-user/arm: Use force_sig() to deliver fpa11 emulation SIGFPE

Message ID 20210924135631.2067582-4-laurent@vivier.eu
State Accepted
Commit babe6d5c88b587d30f72f31a81ce87610b68e952
Headers show
Series [PULL,1/7] linux-user/aarch64: Set siginfo_t addr field for SIGTRAP signals | expand

Commit Message

Laurent Vivier Sept. 24, 2021, 1:56 p.m. UTC 
From: Peter Maydell <peter.maydell@linaro.org>


In the Arm target code, when the fpa11 emulation code tells us we
need to send the guest a SIGFPE, we do this with queue_signal(), but
we are using the wrong si_type, and we aren't setting the _sifields
union members corresponding to either the si_type we are using or the
si_type we should be using.

As the existing comment notes, the kernel code for this calls the old
send_sig() function to deliver the signal.  This eventually results
in the kernel's signal handling code fabricating a siginfo_t with a
SI_KERNEL code and a zero pid and uid.  For QEMU this means we need
to use QEMU_SI_KILL.  We already have a function for that:
force_sig() sets up the whole target_siginfo_t the way we need it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Message-Id: <20210813131809.28655-4-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

---
 linux-user/arm/cpu_loop.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

-- 
2.31.1
diff mbox series

Patch

diff --git a/linux-user/arm/cpu_loop.c b/linux-user/arm/cpu_loop.c
index 0900d18105a1..fb78a1aab308 100644
--- a/linux-user/arm/cpu_loop.c
+++ b/linux-user/arm/cpu_loop.c
@@ -268,16 +268,13 @@  static bool emulate_arm_fpa11(CPUARMState *env, uint32_t opcode)
     ts->fpa.fpsr |= raise & ~enabled;
 
     if (raise & enabled) {
-        target_siginfo_t info = { };
-
         /*
          * The kernel's nwfpe emulator does not pass a real si_code.
-         * It merely uses send_sig(SIGFPE, current, 1).
+         * It merely uses send_sig(SIGFPE, current, 1), which results in
+         * __send_signal() filling out SI_KERNEL with pid and uid 0 (under
+         * the "SEND_SIG_PRIV" case). That's what our force_sig() does.
          */
-        info.si_signo = TARGET_SIGFPE;
-        info.si_code = TARGET_SI_KERNEL;
-
-        queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
+        force_sig(TARGET_SIGFPE);
     } else {
         env->regs[15] += 4;
     }