runtime: use explicit NOFRAME on linux/amd64

This CL marks some linux assembly functions as NOFRAME to avoid relying
on the implicit amd64 NOFRAME heuristic, where NOSPLIT functions
without stack were also marked as NOFRAME.

Updates #58378

Change-Id: I7792cff4f6e539bfa56c02868f2965088ca1975a
Reviewed-on: https://go-review.googlesource.com/c/go/+/466316
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index 8b62120d19d6cd139d15e55a0118558680265fe5..c6fe3279c4ede33cbc3d774cd86dbf9ab558b05f 100644 (file)
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -611,17 +611,23 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                }
        }
 
+       var usefpheuristic bool
+       switch ctxt.Headtype {
+       case objabi.Hwindows, objabi.Hdarwin, objabi.Hlinux:
+       default:
+               usefpheuristic = true
+       }
+
        var bpsize int
        if ctxt.Arch.Family == sys.AMD64 &&
                !p.From.Sym.NoFrame() && // (1) below
-               !(autoffset == 0 && p.From.Sym.NoSplit() && ctxt.Headtype != objabi.Hwindows && ctxt.Headtype != objabi.Hdarwin) && // (2) below
+               !(autoffset == 0 && p.From.Sym.NoSplit() && usefpheuristic) && // (2) below
                !(autoffset == 0 && !hasCall) { // (3) below
                // Make room to save a base pointer.
                // There are 2 cases we must avoid:
                // 1) If noframe is set (which we do for functions which tail call).
                // 2) Scary runtime internals which would be all messed up by frame pointers.
                //    We detect these using a heuristic: frameless nosplit functions.
-               //    Windows and Darwin do not use this heuristic anymore.
                //    TODO: Maybe someday we label them all with NOFRAME and get rid of this heuristic.
                // For performance, we also want to avoid:
                // 3) Frameless leaf functions

diff --git a/src/cmd/link/internal/ld/testdata/stackcheck/main.s b/src/cmd/link/internal/ld/testdata/stackcheck/main.s
index 10f6a3f4c2f492cafc42a86c0633b1a94f04d1e9..623fdda7020a48e12a02decb3b4191b19dd1940d 100644 (file)
--- a/src/cmd/link/internal/ld/testdata/stackcheck/main.s
+++ b/src/cmd/link/internal/ld/testdata/stackcheck/main.s
@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #define NOSPLIT 7
+#define NOFRAME 512
 
 TEXT ·asmMain(SB),0,$0-0
        CALL ·startSelf(SB)
@@ -32,9 +33,9 @@ TEXT ·chainEnd(SB),NOSPLIT,$1000-0 // Should be reported twice
        RET
 
 // Test reporting of rootless recursion
-TEXT ·startRec(SB),NOSPLIT,$0-0
+TEXT ·startRec(SB),NOSPLIT|NOFRAME,$0-0
        CALL ·startRec0(SB)
        RET
-TEXT ·startRec0(SB),NOSPLIT,$0-0
+TEXT ·startRec0(SB),NOSPLIT|NOFRAME,$0-0
        CALL ·startRec(SB)
        RET

diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index c7a89ba5363405c7f9903d9bcbfd14f299ff6e02..9f18d2d7cd0063cfc29d55d1e913c15dd4627b22 100644 (file)
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -325,16 +325,14 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
        MOVL    sig+8(FP),   DI
        MOVQ    info+16(FP), SI
        MOVQ    ctx+24(FP),  DX
-       PUSHQ   BP
-       MOVQ    SP, BP
+       MOVQ    SP, BX          // callee-saved
        ANDQ    $~15, SP     // alignment for x86_64 ABI
        CALL    AX
-       MOVQ    BP, SP
-       POPQ    BP
+       MOVQ    BX, SP
        RET
 
 // Called using C ABI.
-TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME,$0
+TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME|NOFRAME,$0
        // Transition from C ABI to Go ABI.
        PUSH_REGS_HOST_TO_ABI0()
 
@@ -359,7 +357,7 @@ TEXT runtime·sigtramp(SB),NOSPLIT|TOPFRAME,$0
        RET
 
 // Called using C ABI.
-TEXT runtime·sigprofNonGoWrapper<>(SB),NOSPLIT,$0
+TEXT runtime·sigprofNonGoWrapper<>(SB),NOSPLIT|NOFRAME,$0
        // Transition from C ABI to Go ABI.
        PUSH_REGS_HOST_TO_ABI0()
 
@@ -556,7 +554,7 @@ TEXT runtime·futex(SB),NOSPLIT,$0
        RET
 
 // int32 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
-TEXT runtime·clone(SB),NOSPLIT,$0
+TEXT runtime·clone(SB),NOSPLIT|NOFRAME,$0
        MOVL    flags+0(FP), DI
        MOVQ    stk+8(FP), SI
        MOVQ    $0, DX
@@ -620,7 +618,7 @@ nog2:
        SYSCALL
        JMP     -3(PC)  // keep exiting
 
-TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
+TEXT runtime·sigaltstack(SB),NOSPLIT,$0
        MOVQ    new+0(FP), DI
        MOVQ    old+8(FP), SI
        MOVQ    $SYS_sigaltstack, AX