* [PULL 1/1] plugins: use int64_t for the syscall filter return value
2026-06-18 23:47 [PULL 0/1] Plugins update for 2026-06-18 Pierrick Bouvier
@ 2026-06-18 23:47 ` Pierrick Bouvier
2026-06-20 12:40 ` [PULL 0/1] Plugins update for 2026-06-18 Stefan Hajnoczi
1 sibling, 0 replies; 3+ messages in thread
From: Pierrick Bouvier @ 2026-06-18 23:47 UTC (permalink / raw)
To: qemu-devel, peter.maydell, richard.henderson, pbonzini, stefanha
Cc: pierrick.bouvier
From: Ziyang Zhang <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>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
Link: https://lore.kernel.org/qemu-devel/20260618082426.790315-2-functioner@sjtu.edu.cn
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>
---
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 d8d4b373842..3e913cd89ce 100644
--- a/include/plugins/qemu-plugin.h
+++ b/include/plugins/qemu-plugin.h
@@ -871,7 +871,7 @@ 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,
void *userdata);
/**
diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h
index 9356ee836ac..9c2ec8ceaeb 100644
--- a/include/qemu/plugin.h
+++ b/include/qemu/plugin.h
@@ -172,7 +172,7 @@ 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,
@@ -288,7 +288,7 @@ 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 fbe357b7e0f..d257fb9ca90 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -14619,7 +14619,7 @@ 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 4b55aacd2d7..1113bfe5673 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -573,7 +573,7 @@ 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 7c78f182f01..76b2efc61b2 100644
--- a/tests/tcg/plugins/setpc.c
+++ b/tests/tcg/plugins/setpc.c
@@ -27,7 +27,7 @@ static bool vcpu_syscall_filter(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, void *userdata)
+ int64_t *sysret, void *userdata)
{
if (num == MAGIC_SYSCALL) {
if (a1 == SETPC) {
diff --git a/tests/tcg/plugins/syscall.c b/tests/tcg/plugins/syscall.c
index a28d1087840..debec9f09b5 100644
--- a/tests/tcg/plugins/syscall.c
+++ b/tests/tcg/plugins/syscall.c
@@ -176,7 +176,7 @@ static bool vcpu_syscall_filter(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, void *userdata)
+ int64_t *sysret, void *userdata)
{
/* Special syscall to test the filter functionality. */
if (num == 4096 && a1 == 0x66CCFF) {
--
2.47.3
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