{"id":2220666,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2220666/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260407043614.372871-2-alistair.francis@wdc.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.1/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260407043614.372871-2-alistair.francis@wdc.com>","date":"2026-04-07T04:36:10","name":"[1/5] target/riscv: Generate access fault if sc comparison fails","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"f32469e8056b4a815a237a59bab3c5aad2019f76","submitter":{"id":64571,"url":"http://patchwork.ozlabs.org/api/1.1/people/64571/?format=json","name":"Alistair Francis","email":"alistair23@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260407043614.372871-2-alistair.francis@wdc.com/mbox/","series":[{"id":499030,"url":"http://patchwork.ozlabs.org/api/1.1/series/499030/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=499030","date":"2026-04-07T04:36:12","name":"target/riscv: A collection of bug fixes","version":1,"mbox":"http://patchwork.ozlabs.org/series/499030/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2220666/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2220666/checks/","tags":{},"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=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=NTxBsMjc;\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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helo=mail-pg1-x535.google.com","X-Spam_score_int":"-17","X-Spam_score":"-1.8","X-Spam_bar":"-","X-Spam_report":"(-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"From: Alistair Francis \n\nThe RISC-V spec states:\n\n\"For the purposes of memory protection, a failed SC.W may be treated\nlike a store.\"\n\nSo if the comparison in sc.w fails we should still check for alignment\nand do a probe access to check permissions.\n\nResolves: https://gitlab.com/qemu-project/qemu/-/work_items/3323\nResoves: https://gitlab.com/qemu-project/qemu/-/work_items/3136\nSigned-off-by: Alistair Francis \n---\n target/riscv/helper.h | 3 +++\n target/riscv/op_helper.c | 14 ++++++++++++++\n target/riscv/insn_trans/trans_rva.c.inc | 6 ++++++\n 3 files changed, 23 insertions(+)","diff":"diff --git a/target/riscv/helper.h b/target/riscv/helper.h\nindex b785456ee0..af6cfcfc27 100644\n--- a/target/riscv/helper.h\n+++ b/target/riscv/helper.h\n@@ -1289,3 +1289,6 @@ DEF_HELPER_4(vsm4r_vs, void, ptr, ptr, env, i32)\n #ifndef CONFIG_USER_ONLY\n DEF_HELPER_1(ssamoswap_disabled, void, env)\n #endif\n+\n+/* Zalrsc\" SC write probe */\n+DEF_HELPER_FLAGS_3(sc_probe_write, TCG_CALL_NO_WG, void, env, tl, tl)\ndiff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c\nindex 6ccc127c30..b569366369 100644\n--- a/target/riscv/op_helper.c\n+++ b/target/riscv/op_helper.c\n@@ -281,6 +281,20 @@ void helper_cbo_inval(CPURISCVState *env, target_ulong address)\n /* We don't emulate the cache-hierarchy, so we're done. */\n }\n \n+void helper_sc_probe_write(CPURISCVState *env, target_ulong addr,\n+ target_ulong size)\n+{\n+ uintptr_t ra = GETPC();\n+ int mmu_idx = riscv_env_mmu_index(env, false);\n+\n+ if (addr & (size - 1)) {\n+ env->badaddr = addr;\n+ riscv_raise_exception(env, RISCV_EXCP_STORE_AMO_ADDR_MIS, ra);\n+ }\n+\n+ probe_write(env, addr, size, mmu_idx, ra);\n+}\n+\n #ifndef CONFIG_USER_ONLY\n \n target_ulong helper_sret(CPURISCVState *env)\ndiff --git a/target/riscv/insn_trans/trans_rva.c.inc b/target/riscv/insn_trans/trans_rva.c.inc\nindex a7a3278d24..62c0fe673d 100644\n--- a/target/riscv/insn_trans/trans_rva.c.inc\n+++ b/target/riscv/insn_trans/trans_rva.c.inc\n@@ -90,6 +90,12 @@ static bool gen_sc(DisasContext *ctx, arg_atomic *a, MemOp mop)\n */\n TCGBar bar_strl = (ctx->ztso || a->rl) ? TCG_BAR_STRL : 0;\n tcg_gen_mb(TCG_MO_ALL + a->aq * TCG_BAR_LDAQ + bar_strl);\n+ /*\n+ * \"For the purposes of memory protection, a failed SC.W may be treated\n+ * like a store.\" so let's check the write access permissions\n+ */\n+ gen_helper_sc_probe_write(tcg_env, src1,\n+ tcg_constant_tl(memop_size(mop)));\n gen_set_gpr(ctx, a->rd, tcg_constant_tl(1));\n \n gen_set_label(l2);\n","prefixes":["1/5"]}