From: Ziyang Zhang <functioner@sjtu.edu.cn>
To: qemu-devel <qemu-devel@nongnu.org>
Cc: Riku Voipio <riku.voipio@iki.fi>,
Laurent Vivier <laurent@vivier.eu>,
Alex Bennee <alex.bennee@linaro.org>,
Alexandre Iooss <erdnaxe@crans.org>,
Mahmoud Mandour <ma.mandourr@gmail.com>,
Pierrick Bouvier <pierrick.bouvier@linaro.org>,
Richard Henderson <richard.henderson@linaro.org>,
Zhengwei Qi <qizhwei@sjtu.edu.cn>,
Yun Wang <yunwang94@sjtu.edu.cn>,
Mingyuan Xia <xiamy@ultrarisc.com>,
Kailiang Xu <xukl2019@sjtu.edu.cn>,
Ziyang Zhang <functioner@sjtu.edu.cn>
Subject: [PATCH 1/1] plugins: use int64_t for the syscall filter return value
Date: Fri, 12 Jun 2026 13:56:42 +0800 [thread overview]
Message-ID: <20260612055642.589337-2-functioner@sjtu.edu.cn> (raw)
In-Reply-To: <20260612055642.589337-1-functioner@sjtu.edu.cn>
The syscall return value passed back through the syscall filter
callback is semantically signed: negative values encode errno codes.
Declaring the sysret pointer as uint64_t * is therefore misleading and
forces callers to launder the value through an unsigned temporary.
Change the sysret pointer to int64_t * across the public plugin API
typedef (qemu_plugin_vcpu_syscall_filter_cb_t), the internal
qemu_plugin_vcpu_syscall_filter() prototypes and stub, its
implementation in plugins/core.c, the linux-user caller, and the
in-tree example plugins.
Signed-off-by: Ziyang Zhang <functioner@sjtu.edu.cn>
---
include/plugins/qemu-plugin.h | 2 +-
include/qemu/plugin.h | 4 ++--
linux-user/syscall.c | 2 +-
plugins/core.c | 2 +-
tests/tcg/plugins/setpc.c | 2 +-
tests/tcg/plugins/syscall.c | 2 +-
6 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/plugins/qemu-plugin.h b/include/plugins/qemu-plugin.h
index 4eb1d2cd85..8eb10b1f48 100644
--- a/include/plugins/qemu-plugin.h
+++ b/include/plugins/qemu-plugin.h
@@ -870,7 +870,7 @@ typedef bool
int64_t num, uint64_t a1, uint64_t a2,
uint64_t a3, uint64_t a4, uint64_t a5,
uint64_t a6, uint64_t a7, uint64_t a8,
- uint64_t *sysret);
+ int64_t *sysret);
/**
* typedef qemu_plugin_vcpu_syscall_ret_cb_t - vCPU syscall return callback
diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
index ddd77bd82c..1ce4b281c1 100644
--- a/include/qemu/plugin.h
+++ b/include/qemu/plugin.h
@@ -174,7 +174,7 @@ bool
qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,
uint64_t a2, uint64_t a3, uint64_t a4,
uint64_t a5, uint64_t a6, uint64_t a7,
- uint64_t a8, uint64_t *sysret);
+ uint64_t a8, int64_t *sysret);
void qemu_plugin_vcpu_mem_cb(CPUState *cpu, uint64_t vaddr,
uint64_t value_low,
@@ -290,7 +290,7 @@ static inline bool
qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,
uint64_t a2, uint64_t a3, uint64_t a4,
uint64_t a5, uint64_t a6, uint64_t a7,
- uint64_t a8, uint64_t *sysret)
+ uint64_t a8, int64_t *sysret)
{
return false;
}
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index f4b74ad350..63c0a5f8f3 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -14378,7 +14378,7 @@ static bool send_through_syscall_filters(CPUState *cpu, int num,
abi_long arg7, abi_long arg8,
abi_long *sysret)
{
- uint64_t sysret64 = 0;
+ int64_t sysret64 = 0;
bool filtered = qemu_plugin_vcpu_syscall_filter(cpu, num, arg1, arg2,
arg3, arg4, arg5, arg6,
arg7, arg8, &sysret64);
diff --git a/plugins/core.c b/plugins/core.c
index 2324bbffa3..58f293462a 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -596,7 +596,7 @@ bool
qemu_plugin_vcpu_syscall_filter(CPUState *cpu, int64_t num, uint64_t a1,
uint64_t a2, uint64_t a3, uint64_t a4,
uint64_t a5, uint64_t a6, uint64_t a7,
- uint64_t a8, uint64_t *sysret)
+ uint64_t a8, int64_t *sysret)
{
struct qemu_plugin_cb *cb, *next;
enum qemu_plugin_event ev = QEMU_PLUGIN_EV_VCPU_SYSCALL_FILTER;
diff --git a/tests/tcg/plugins/setpc.c b/tests/tcg/plugins/setpc.c
index 8f2d025e24..23862eaaf0 100644
--- a/tests/tcg/plugins/setpc.c
+++ b/tests/tcg/plugins/setpc.c
@@ -27,7 +27,7 @@ static bool vcpu_syscall_filter(qemu_plugin_id_t id, unsigned int vcpu_index,
int64_t num, uint64_t a1, uint64_t a2,
uint64_t a3, uint64_t a4, uint64_t a5,
uint64_t a6, uint64_t a7, uint64_t a8,
- uint64_t *sysret)
+ int64_t *sysret)
{
if (num == MAGIC_SYSCALL) {
if (a1 == SETPC) {
diff --git a/tests/tcg/plugins/syscall.c b/tests/tcg/plugins/syscall.c
index 5658f83087..76d52b98aa 100644
--- a/tests/tcg/plugins/syscall.c
+++ b/tests/tcg/plugins/syscall.c
@@ -174,7 +174,7 @@ static bool vcpu_syscall_filter(qemu_plugin_id_t id, unsigned int vcpu_index,
int64_t num, uint64_t a1, uint64_t a2,
uint64_t a3, uint64_t a4, uint64_t a5,
uint64_t a6, uint64_t a7, uint64_t a8,
- uint64_t *sysret)
+ int64_t *sysret)
{
/* Special syscall to test the filter functionality. */
if (num == 4096 && a1 == 0x66CCFF) {
--
2.34.1
next prev parent reply other threads:[~2026-06-12 5:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 5:56 [PATCH 0/1] plugins: fix syscall filter return value type Ziyang Zhang
2026-06-12 5:56 ` Ziyang Zhang [this message]
2026-06-12 10:43 ` [PATCH 1/1] plugins: use int64_t for the syscall filter return value Alex Bennée
2026-06-12 12:48 ` Ziyang Zhang
2026-06-12 7:59 ` [PATCH 0/1] plugins: fix syscall filter return value type Ziyang Zhang
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