target-m68k/m68k-semi.c: Log when put_user for returning values fails
Abstract out the use of put_user for returning semihosting call results, so that we can log when a guest erroneously attempts a semihosting call with an unwritable argument block. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
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				@ -133,24 +133,44 @@ static void translate_stat(CPUM68KState *env, target_ulong addr, struct stat *s)
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    unlock_user(p, addr, sizeof(struct m68k_gdb_stat));
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}
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static void m68k_semi_return_u32(CPUM68KState *env, uint32_t ret, uint32_t err)
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{
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    target_ulong args = env->dregs[1];
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    if (put_user_u32(ret, args) ||
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        put_user_u32(err, args + 4)) {
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        /* The m68k semihosting ABI does not provide any way to report this
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         * error to the guest, so the best we can do is log it in qemu.
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         * It is always a guest error not to pass us a valid argument block.
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         */
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        qemu_log_mask(LOG_GUEST_ERROR, "m68k-semihosting: return value "
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                      "discarded because argument block not writable\n");
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    }
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}
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static void m68k_semi_return_u64(CPUM68KState *env, uint64_t ret, uint32_t err)
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{
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    target_ulong args = env->dregs[1];
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    if (put_user_u32(ret >> 32, args) ||
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        put_user_u32(ret, args + 4) ||
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        put_user_u32(err, args + 8)) {
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        /* No way to report this via m68k semihosting ABI; just log it */
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        qemu_log_mask(LOG_GUEST_ERROR, "m68k-semihosting: return value "
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                      "discarded because argument block not writable\n");
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    }
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}
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static int m68k_semi_is_fseek;
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static void m68k_semi_cb(CPUM68KState *env, target_ulong ret, target_ulong err)
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{
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    target_ulong args;
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    args = env->dregs[1];
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    if (m68k_semi_is_fseek) {
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        /* FIXME: We've already lost the high bits of the fseek
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           return value.  */
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        /* FIXME - handle put_user() failure */
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        put_user_u32(0, args);
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        args += 4;
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        m68k_semi_return_u64(env, ret, err);
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        m68k_semi_is_fseek = 0;
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    } else {
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        m68k_semi_return_u32(env, ret, err);
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    }
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    /* FIXME - handle put_user() failure */
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    put_user_u32(ret, args);
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    put_user_u32(err, args + 4);
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}
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/* Read the input value from the argument block; fail the semihosting
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@ -269,10 +289,7 @@ void do_m68k_semihosting(CPUM68KState *env, int nr)
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                               arg0, off, arg3);
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            } else {
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                off = lseek(arg0, off, arg3);
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                /* FIXME - handle put_user() failure */
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                put_user_u32(off >> 32, args);
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                put_user_u32(off, args + 4);
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                put_user_u32(errno, args + 8);
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                m68k_semi_return_u64(env, off, errno);
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            }
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            return;
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        }
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@ -444,7 +461,5 @@ void do_m68k_semihosting(CPUM68KState *env, int nr)
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        result = 0;
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    }
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failed:
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    /* FIXME - handle put_user() failure */
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    put_user_u32(result, args);
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    put_user_u32(errno, args + 4);
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    m68k_semi_return_u32(env, result, errno);
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}
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