Merge pull request #25388 from alexrp/ksigaction

`std.os.linux`: Fix `k_sigaction` ABI issue on platforms w/o `SA_RESTORER`

lib/libc/musl/arch/hexagon/bits/signal.h

@@ -61,7 +61,6 @@ typedef struct __ucontext {
 #define SA_RESTART    0x10000000
 #define SA_NODEFER    0x40000000
 #define SA_RESETHAND  0x80000000
-#define SA_RESTORER   0x04000000
 
 #endif
 

lib/libc/musl/arch/riscv32/bits/signal.h

@@ -78,7 +78,6 @@ typedef struct __ucontext
 #define SA_RESTART   0x10000000
 #define SA_NODEFER   0x40000000
 #define SA_RESETHAND 0x80000000
-#define SA_RESTORER  0x04000000
 
 #endif
 

lib/libc/musl/src/signal/hexagon/restore.s

@@ -1,11 +0,0 @@
-// TODO - Test this if sa_restorer is ever supported in our kernel
-.global __restore
-.type __restore,%function
-.global __restore_rt
-.type __restore_rt,%function
-__restore:
-__restore_rt:
-	r6 = #139				// SYS_rt_sigreturn
-	trap0(#0)
-.size __restore, .-__restore
-.size __restore_rt, .-__restore_rt

lib/libc/musl/src/signal/loongarch64/restore.s

@@ -1,10 +0,0 @@
-.global __restore_rt
-.global __restore
-.hidden __restore_rt
-.hidden __restore
-.type   __restore_rt,@function
-.type   __restore,@function
-__restore_rt:
-__restore:
-	li.w    $a7, 139
-	syscall 0

lib/libc/musl/src/signal/riscv32/restore.s

@@ -1,10 +0,0 @@
-.global __restore
-.hidden __restore
-.type __restore, %function
-__restore:
-.global __restore_rt
-.hidden __restore_rt
-.type __restore_rt, %function
-__restore_rt:
-	li a7, 139 # SYS_rt_sigreturn
-	ecall

lib/libc/musl/src/signal/riscv64/restore.s

@@ -1,10 +0,0 @@
-.global __restore
-.hidden __restore
-.type __restore, %function
-__restore:
-.global __restore_rt
-.hidden __restore_rt
-.type __restore_rt, %function
-__restore_rt:
-	li a7, 139 # SYS_rt_sigreturn
-	ecall

lib/std/os/linux.zig

@@ -15,8 +15,10 @@ const dl = @import("../dynamic_library.zig");
 const native_arch = builtin.cpu.arch;
 const native_abi = builtin.abi;
 const native_endian = native_arch.endian();
+const is_loongarch = native_arch.isLoongArch();
 const is_mips = native_arch.isMIPS();
 const is_ppc = native_arch.isPowerPC();
+const is_riscv = native_arch.isRISCV();
 const is_sparc = native_arch.isSPARC();
 const iovec = std.posix.iovec;
 const iovec_const = std.posix.iovec_const;
@@ -1868,15 +1870,23 @@ pub fn sigaction(sig: u8, noalias act: ?*const Sigaction, noalias oact: ?*Sigact
     const mask_size = @sizeOf(@TypeOf(ksa.mask));
 
     if (act) |new| {
-        // Zig needs to install our arch restorer function with any signal handler, so
-        // must copy the Sigaction struct
-        const restorer_fn = if ((new.flags & SA.SIGINFO) != 0) &restore_rt else &restore;
-        ksa = k_sigaction{
-            .handler = new.handler.handler,
-            .flags = new.flags | SA.RESTORER,
-            .mask = new.mask,
-            .restorer = @ptrCast(restorer_fn),
-        };
+        if (native_arch == .hexagon or is_loongarch or is_mips or is_riscv) {
+            ksa = .{
+                .handler = new.handler.handler,
+                .flags = new.flags,
+                .mask = new.mask,
+            };
+        } else {
+            // Zig needs to install our arch restorer function with any signal handler, so
+            // must copy the Sigaction struct
+            const restorer_fn = if ((new.flags & SA.SIGINFO) != 0) &restore_rt else &restore;
+            ksa = .{
+                .handler = new.handler.handler,
+                .flags = new.flags | SA.RESTORER,
+                .mask = new.mask,
+                .restorer = @ptrCast(restorer_fn),
+            };
+        }
     }
 
     const ksa_arg = if (act != null) @intFromPtr(&ksa) else 0;
@@ -3668,7 +3678,6 @@ pub const SA = if (is_mips) struct {
     pub const RESETHAND = 0x80000000;
     pub const ONSTACK = 0x08000000;
     pub const NODEFER = 0x40000000;
-    pub const RESTORER = 0x04000000;
 } else if (is_sparc) struct {
     pub const NOCLDSTOP = 0x8;
     pub const NOCLDWAIT = 0x100;
@@ -3678,6 +3687,14 @@ pub const SA = if (is_mips) struct {
     pub const ONSTACK = 0x1;
     pub const NODEFER = 0x20;
     pub const RESTORER = 0x04000000;
+} else if (native_arch == .hexagon or is_loongarch or is_riscv) struct {
+    pub const NOCLDSTOP = 1;
+    pub const NOCLDWAIT = 2;
+    pub const SIGINFO = 4;
+    pub const RESTART = 0x10000000;
+    pub const RESETHAND = 0x80000000;
+    pub const ONSTACK = 0x08000000;
+    pub const NODEFER = 0x40000000;
 } else struct {
     pub const NOCLDSTOP = 1;
     pub const NOCLDWAIT = 2;
@@ -5743,13 +5760,18 @@ const k_sigaction_funcs = struct {
     const restorer = *const fn () callconv(.c) void;
 };
 
-/// Kernel sigaction struct, as expected by the `rt_sigaction` syscall.  Includes restorer.
+/// Kernel sigaction struct, as expected by the `rt_sigaction` syscall.  Includes `restorer` on
+/// targets where userspace is responsible for hooking up `rt_sigreturn`.
 pub const k_sigaction = switch (native_arch) {
     .mips, .mipsel, .mips64, .mips64el => extern struct {
         flags: c_uint,
         handler: k_sigaction_funcs.handler,
         mask: sigset_t,
-        restorer: k_sigaction_funcs.restorer,
+    },
+    .hexagon, .loongarch32, .loongarch64, .riscv32, .riscv64 => extern struct {
+        handler: k_sigaction_funcs.handler,
+        flags: c_ulong,
+        mask: sigset_t,
     },
     else => extern struct {
         handler: k_sigaction_funcs.handler,

lib/std/os/linux/hexagon.zig

@@ -128,16 +128,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub const restore = restore_rt;
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ trap0(#0)
-        :
-        : [number] "{r6}" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const F = struct {
     pub const DUPFD = 0;
     pub const GETFD = 1;

lib/std/os/linux/loongarch64.zig

@@ -135,17 +135,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub const restore = restore_rt;
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ or $a7, $zero, %[number]
-        \\ syscall 0
-        :
-        : [number] "r" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const msghdr = extern struct {
     name: ?*sockaddr,
     namelen: socklen_t,

lib/std/os/linux/mips.zig

@@ -241,22 +241,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub fn restore() callconv(.naked) noreturn {
-    asm volatile (
-        \\ syscall
-        :
-        : [number] "{$2}" (@intFromEnum(SYS.sigreturn)),
-        : .{ .r1 = true, .r3 = true, .r4 = true, .r5 = true, .r6 = true, .r7 = true, .r8 = true, .r9 = true, .r10 = true, .r11 = true, .r12 = true, .r13 = true, .r14 = true, .r15 = true, .r24 = true, .r25 = true, .hi = true, .lo = true, .memory = true });
-}
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ syscall
-        :
-        : [number] "{$2}" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const F = struct {
     pub const DUPFD = 0;
     pub const GETFD = 1;

lib/std/os/linux/mips64.zig

@@ -220,22 +220,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub fn restore() callconv(.naked) noreturn {
-    asm volatile (
-        \\ syscall
-        :
-        : [number] "{$2}" (@intFromEnum(SYS.rt_sigreturn)),
-        : .{ .r1 = true, .r3 = true, .r4 = true, .r5 = true, .r6 = true, .r7 = true, .r8 = true, .r9 = true, .r10 = true, .r11 = true, .r12 = true, .r13 = true, .r14 = true, .r15 = true, .r24 = true, .r25 = true, .hi = true, .lo = true, .memory = true });
-}
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ syscall
-        :
-        : [number] "{$2}" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const F = struct {
     pub const DUPFD = 0;
     pub const GETFD = 1;

lib/std/os/linux/riscv32.zig

@@ -135,16 +135,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub const restore = restore_rt;
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ ecall
-        :
-        : [number] "{x17}" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const F = struct {
     pub const DUPFD = 0;
     pub const GETFD = 1;

lib/std/os/linux/riscv64.zig

@@ -135,16 +135,6 @@ pub fn clone() callconv(.naked) usize {
     );
 }
 
-pub const restore = restore_rt;
-
-pub fn restore_rt() callconv(.naked) noreturn {
-    asm volatile (
-        \\ ecall
-        :
-        : [number] "{x17}" (@intFromEnum(SYS.rt_sigreturn)),
-    );
-}
-
 pub const F = struct {
     pub const DUPFD = 0;
     pub const GETFD = 1;

src/libs/musl.zig

@@ -1538,13 +1538,11 @@ const src_files = [_][]const u8{
     "musl/src/signal/arm/sigsetjmp.s",
     "musl/src/signal/block.c",
     "musl/src/signal/getitimer.c",
-    "musl/src/signal/hexagon/restore.s",
     "musl/src/signal/hexagon/sigsetjmp.s",
     "musl/src/signal/i386/restore.s",
     "musl/src/signal/i386/sigsetjmp.s",
     "musl/src/signal/kill.c",
     "musl/src/signal/killpg.c",
-    "musl/src/signal/loongarch64/restore.s",
     "musl/src/signal/loongarch64/sigsetjmp.s",
     "musl/src/signal/m68k/sigsetjmp.s",
     "musl/src/signal/mips64/sigsetjmp.s",
@@ -1558,9 +1556,7 @@ const src_files = [_][]const u8{
     "musl/src/signal/psignal.c",
     "musl/src/signal/raise.c",
     "musl/src/signal/restore.c",
-    "musl/src/signal/riscv32/restore.s",
     "musl/src/signal/riscv32/sigsetjmp.s",
-    "musl/src/signal/riscv64/restore.s",
     "musl/src/signal/riscv64/sigsetjmp.s",
     "musl/src/signal/s390x/restore.s",
     "musl/src/signal/s390x/sigsetjmp.s",