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[RFC 2/4] linux-user/signal.c: Create a common rewind_if_in_safe_syscall


From: Warner Losh
Subject: [RFC 2/4] linux-user/signal.c: Create a common rewind_if_in_safe_syscall
Date: Sun, 7 Nov 2021 19:37:36 -0700

All instances of rewind_if_in_safe_syscall are the same, differing only
in how the instruction point is fetched from the ucontext and the size
of the registers. Use host_signal_pc and new host_signal_set_pc
interfaces to fetch the pointer to the PC and adjust if needed. Delete
all the old copies of rewind_if_in_safe_syscall.

Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 linux-user/host/aarch64/hostdep.h | 20 --------------------
 linux-user/host/arm/hostdep.h     | 20 --------------------
 linux-user/host/i386/hostdep.h    | 20 --------------------
 linux-user/host/ppc64/hostdep.h   | 20 --------------------
 linux-user/host/riscv/hostdep.h   | 20 --------------------
 linux-user/host/s390x/hostdep.h   | 20 --------------------
 linux-user/host/x86_64/hostdep.h  | 20 --------------------
 linux-user/signal.c               | 18 +++++++++++++++++-
 8 files changed, 17 insertions(+), 141 deletions(-)

diff --git a/linux-user/host/aarch64/hostdep.h 
b/linux-user/host/aarch64/hostdep.h
index a8d41a21ad..39299d798a 100644
--- a/linux-user/host/aarch64/hostdep.h
+++ b/linux-user/host/aarch64/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    __u64 *pcreg = &uc->uc_mcontext.pc;
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/arm/hostdep.h b/linux-user/host/arm/hostdep.h
index 9276fe6ceb..86b137875a 100644
--- a/linux-user/host/arm/hostdep.h
+++ b/linux-user/host/arm/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    unsigned long *pcreg = &uc->uc_mcontext.arm_pc;
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/i386/hostdep.h b/linux-user/host/i386/hostdep.h
index 073be74d87..ce7136501f 100644
--- a/linux-user/host/i386/hostdep.h
+++ b/linux-user/host/i386/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    greg_t *pcreg = &uc->uc_mcontext.gregs[REG_EIP];
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/ppc64/hostdep.h b/linux-user/host/ppc64/hostdep.h
index 98979ad917..0c290dd904 100644
--- a/linux-user/host/ppc64/hostdep.h
+++ b/linux-user/host/ppc64/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    unsigned long *pcreg = &uc->uc_mcontext.gp_regs[PT_NIP];
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/riscv/hostdep.h b/linux-user/host/riscv/hostdep.h
index 2ba07456ae..7f67c22868 100644
--- a/linux-user/host/riscv/hostdep.h
+++ b/linux-user/host/riscv/hostdep.h
@@ -11,24 +11,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    unsigned long *pcreg = &uc->uc_mcontext.__gregs[REG_PC];
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/s390x/hostdep.h b/linux-user/host/s390x/hostdep.h
index 4f0171f36f..d801145854 100644
--- a/linux-user/host/s390x/hostdep.h
+++ b/linux-user/host/s390x/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    unsigned long *pcreg = &uc->uc_mcontext.psw.addr;
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/host/x86_64/hostdep.h b/linux-user/host/x86_64/hostdep.h
index a4fefb5114..9c62bd26bd 100644
--- a/linux-user/host/x86_64/hostdep.h
+++ b/linux-user/host/x86_64/hostdep.h
@@ -15,24 +15,4 @@
 /* We have a safe-syscall.inc.S */
 #define HAVE_SAFE_SYSCALL
 
-#ifndef __ASSEMBLER__
-
-/* These are defined by the safe-syscall.inc.S file */
-extern char safe_syscall_start[];
-extern char safe_syscall_end[];
-
-/* Adjust the signal context to rewind out of safe-syscall if we're in it */
-static inline void rewind_if_in_safe_syscall(void *puc)
-{
-    ucontext_t *uc = puc;
-    greg_t *pcreg = &uc->uc_mcontext.gregs[REG_RIP];
-
-    if (*pcreg > (uintptr_t)safe_syscall_start
-        && *pcreg < (uintptr_t)safe_syscall_end) {
-        *pcreg = (uintptr_t)safe_syscall_start;
-    }
-}
-
-#endif /* __ASSEMBLER__ */
-
 #endif
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 81c45bfce9..dafdf46b93 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -793,7 +793,23 @@ int queue_signal(CPUArchState *env, int sig, int si_type,
     return 1; /* indicates that the signal was queued */
 }
 
-#ifndef HAVE_SAFE_SYSCALL
+#ifdef HAVE_SAFE_SYSCALL
+/* These are defined by the safe-syscall.inc.S file */
+extern char safe_syscall_start[];
+extern char safe_syscall_end[];
+
+/* Adjust the signal context to rewind out of safe-syscall if we're in it */
+static inline void rewind_if_in_safe_syscall(void *puc)
+{
+    ucontext_t *uc = (ucontext_t *)puc;
+    uintptr_t pcreg = host_signal_pc(uc);
+
+    if (pcreg > (uintptr_t)safe_syscall_start
+        && pcreg < (uintptr_t)safe_syscall_end) {
+        host_signal_set_pc(uc, (uintptr_t)safe_syscall_start);
+    }
+}
+#else
 static inline void rewind_if_in_safe_syscall(void *puc)
 {
     /* Default version: never rewind */
-- 
2.33.0




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