[{"id":3687103,"web_url":"http://patchwork.ozlabs.org/comment/3687103/","msgid":"<5357761f-be70-4543-99d5-9fda2303811f@linaro.org>","list_archive_url":null,"date":"2026-05-06T14:08:35","subject":"Re: [PATCH v5 10/15] target/arm: fault on tag store to canonical tag","submitter":{"id":72104,"url":"http://patchwork.ozlabs.org/api/people/72104/","name":"Richard Henderson","email":"richard.henderson@linaro.org"},"content":"On 5/4/26 10:50, Gabriel Brookman wrote:\n> +static void canonical_tag_write_fail(CPUARMState *env,\n> + uint64_t dirty_ptr, uintptr_t ra)\n> +{\n> + uint64_t syn;\n> +\n> + env->exception.vaddress = dirty_ptr;\n> +\n> + syn = syn_data_abort_no_iss(arm_current_el(env) != 0, 0, 0, 0, 0, 1, 0);\n> + syn |= BIT_ULL(42); /* TnD is bit 42 */\n> +\n> + raise_exception_ra(env, EXCP_DATA_ABORT, syn, exception_target_el(env), ra);\n> + g_assert_not_reached();\n> +}\n> +\n\nCould be marked G_NORETURN for documentation, though I'd expect the compiler to notice and \ngenerate the same code either way. No need for the assert, because raise_exception_ra is \nalready marked NORETURN.\n\n\n> @@ -433,18 +454,23 @@ static inline void do_st2g(CPUARMState *env, uint64_t ptr, uint64_t xt,\n> if (mem1) {\n> tag |= tag << 4;\n> qatomic_set(mem1, tag);\n> + } else if (mtx) {\n> + /* Writing tags to canonically tagged memory region: faults */\n> + canonical_tag_write_fail(env, ptr, ra);\n> + return;\n> }\n\nNo need for return after noreturn function, and you're likely to get a static code \nanalysis warning for unreachable code.\n\nWith that,\nReviewed-by: Richard Henderson \n\nr~","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=tD5lBB/a;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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