[v3] Unaligned access for user-only

[PATCH v3 49/66] linux-user: Add code for PR_GET/SET_UNALIGN

Richard Henderson posted 66 patches 2 years, 10 months ago

Diff against v2
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Maintainers: Alistair Francis <Alistair.Francis@wdc.com>, Eduardo Habkost <ehabkost@redhat.com>, Artyom Tarasenko <atar4qemu@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, Richard Henderson <richard.henderson@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Marek Vasut <marex@denx.de>, Alistair Francis <alistair.francis@wdc.com>, Greg Kurz <groug@kaod.org>, Michael Rolnik <mrolnik@gmail.com>, Stefan Weil <sw@weilnetz.de>, Yoshinori Sato <ysato@users.sourceforge.jp>, Mahmoud Mandour <ma.mandourr@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Stafford Horne <shorne@gmail.com>, Alexandre Iooss <erdnaxe@crans.org>, David Hildenbrand <david@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>, Palmer Dabbelt <palmer@dabbelt.com>, Aurelien Jarno <aurelien@aurel32.net>, "Alex Bennée" <alex.bennee@linaro.org>, Chris Wulff <crwulff@gmail.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Riku Voipio <riku.voipio@iki.fi>, Laurent Vivier <laurent@vivier.eu>, Paolo Bonzini <pbonzini@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Bin Meng <bin.meng@windriver.com>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Max Filippov <jcmvbkbc@gmail.com>, Thomas Huth <thuth@redhat.com>, Taylor Simpson <tsimpson@quicinc.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Cornelia Huck <cohuck@redhat.com>

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[PATCH v3 49/66] linux-user: Add code for PR_GET/SET_UNALIGN

Posted by Richard Henderson 2 years, 10 months ago

This requires extra work for each target, but adds the
common syscall code, and the necessary flag in CPUState.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/hw/core/cpu.h |  3 +++
 linux-user/syscall.c  | 21 +++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index b7d5bc1200..088b2d1adf 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -412,6 +412,9 @@ struct CPUState {
 
     bool ignore_memory_transaction_failures;
 
+    /* Used for user-only emulation of prctl(PR_SET_UNALIGN). */
+    bool prctl_unalign_sigbus;
+
     struct hax_vcpu_state *hax_vcpu;
 
     struct hvf_vcpu_state *hvf;
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index e303a9da7f..b2e3c28b41 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6640,6 +6640,25 @@ static abi_long do_prctl(CPUArchState *env, abi_long option, abi_long arg2,
         }
         return do_prctl_get_tagged_addr_ctrl(env);
 
+    /*
+     * We only implement PR_UNALIGN_SIGBUS, and only for those targets
+     * who have had their translator updated to insert MO_ALIGN.
+     */
+#if 0
+    case PR_GET_UNALIGN:
+        {
+            CPUState *cs = env_cpu(env);
+            uint32_t res = PR_UNALIGN_NOPRINT;
+            if (cs->prctl_unalign_sigbus) {
+                res |= PR_UNALIGN_SIGBUS;
+            }
+            return put_user_u32(res, arg2);
+        }
+    case PR_SET_UNALIGN:
+        env_cpu(env)->prctl_unalign_sigbus = arg2 & PR_UNALIGN_SIGBUS;
+        return 0;
+#endif
+
     case PR_GET_DUMPABLE:
     case PR_SET_DUMPABLE:
     case PR_GET_KEEPCAPS:
@@ -6682,8 +6701,6 @@ static abi_long do_prctl(CPUArchState *env, abi_long option, abi_long arg2,
     case PR_SET_THP_DISABLE:
     case PR_GET_TSC:
     case PR_SET_TSC:
-    case PR_GET_UNALIGN:
-    case PR_SET_UNALIGN:
     default:
         /* Disable to prevent the target disabling stuff we need. */
         return -TARGET_EINVAL;
-- 
2.25.1