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-rw-r--r--src/runtime/malloc.go15
-rw-r--r--src/runtime/stubs_linux.go9
-rw-r--r--src/runtime/stubs_nonlinux.go12
-rw-r--r--src/runtime/sys_linux_386.s9
-rw-r--r--src/runtime/sys_linux_amd64.s9
-rw-r--r--src/runtime/sys_linux_arm.s10
-rw-r--r--src/runtime/sys_linux_arm64.s10
-rw-r--r--src/runtime/sys_linux_mips64x.s10
-rw-r--r--src/runtime/sys_linux_mipsx.s10
-rw-r--r--src/runtime/sys_linux_ppc64x.s9
-rw-r--r--src/runtime/sys_linux_s390x.s10
11 files changed, 113 insertions, 0 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index 7517f1284e..2e6c3aca0a 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -312,6 +312,15 @@ func mallocinit() {
// When that gets used up, we'll start asking the kernel
// for any memory anywhere.
+ // We want to start the arena low, but if we're linked
+ // against C code, it's possible global constructors
+ // have called malloc and adjusted the process' brk.
+ // Query the brk so we can avoid trying to map the
+ // arena over it (which will cause the kernel to put
+ // the arena somewhere else, likely at a high
+ // address).
+ procBrk := sbrk0()
+
// If we fail to allocate, try again with a smaller arena.
// This is necessary on Android L where we share a process
// with ART, which reserves virtual memory aggressively.
@@ -336,6 +345,12 @@ func mallocinit() {
// to a MB boundary.
p = round(firstmoduledata.end+(1<<18), 1<<20)
pSize = bitmapSize + spansSize + arenaSize + _PageSize
+ if p <= procBrk && procBrk < p+pSize {
+ // Move the start above the brk,
+ // leaving some room for future brk
+ // expansion.
+ p = round(procBrk+(1<<20), 1<<20)
+ }
p = uintptr(sysReserve(unsafe.Pointer(p), pSize, &reserved))
if p != 0 {
break
diff --git a/src/runtime/stubs_linux.go b/src/runtime/stubs_linux.go
new file mode 100644
index 0000000000..d10f657197
--- /dev/null
+++ b/src/runtime/stubs_linux.go
@@ -0,0 +1,9 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux
+
+package runtime
+
+func sbrk0() uintptr
diff --git a/src/runtime/stubs_nonlinux.go b/src/runtime/stubs_nonlinux.go
new file mode 100644
index 0000000000..e1ea05cf0b
--- /dev/null
+++ b/src/runtime/stubs_nonlinux.go
@@ -0,0 +1,12 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !linux
+
+package runtime
+
+// sbrk0 returns the current process brk, or 0 if not implemented.
+func sbrk0() uintptr {
+ return 0
+}
diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
index a369792d78..2eb4b1e665 100644
--- a/src/runtime/sys_linux_386.s
+++ b/src/runtime/sys_linux_386.s
@@ -596,3 +596,12 @@ TEXT runtime·socket(SB),NOSPLIT,$0-16
INVOKE_SYSCALL
MOVL AX, ret+12(FP)
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-4
+ // Implemented as brk(NULL).
+ MOVL $45, AX // syscall - brk
+ MOVL $0, BX // NULL
+ INVOKE_SYSCALL
+ MOVL AX, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index be6f396cfa..c2b1376fa9 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -598,3 +598,12 @@ TEXT runtime·socket(SB),NOSPLIT,$0-20
SYSCALL
MOVL AX, ret+16(FP)
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-8
+ // Implemented as brk(NULL).
+ MOVQ $0, DI
+ MOVL $12, AX // syscall entry
+ SYSCALL
+ MOVQ AX, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_arm.s b/src/runtime/sys_linux_arm.s
index 8afc71f059..0244613e67 100644
--- a/src/runtime/sys_linux_arm.s
+++ b/src/runtime/sys_linux_arm.s
@@ -48,6 +48,7 @@
#define SYS_access (SYS_BASE + 33)
#define SYS_connect (SYS_BASE + 283)
#define SYS_socket (SYS_BASE + 281)
+#define SYS_brk (SYS_BASE + 45)
#define ARM_BASE (SYS_BASE + 0x0f0000)
@@ -504,3 +505,12 @@ TEXT runtime·socket(SB),NOSPLIT,$0
SWI $0
MOVW R0, ret+12(FP)
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-4
+ // Implemented as brk(NULL).
+ MOVW $0, R0
+ MOVW $SYS_brk, R7
+ SWI $0
+ MOVW R0, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_arm64.s b/src/runtime/sys_linux_arm64.s
index 204aee7c51..e921f9906c 100644
--- a/src/runtime/sys_linux_arm64.s
+++ b/src/runtime/sys_linux_arm64.s
@@ -46,6 +46,7 @@
#define SYS_faccessat 48
#define SYS_socket 198
#define SYS_connect 203
+#define SYS_brk 214
TEXT runtime·exit(SB),NOSPLIT,$-8-4
MOVW code+0(FP), R0
@@ -483,3 +484,12 @@ TEXT runtime·socket(SB),NOSPLIT,$0-20
SVC
MOVW R0, ret+16(FP)
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-8
+ // Implemented as brk(NULL).
+ MOVD $0, R0
+ MOVD $SYS_brk, R8
+ SVC
+ MOVD R0, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_mips64x.s b/src/runtime/sys_linux_mips64x.s
index a4bcc72dd8..27de7b0901 100644
--- a/src/runtime/sys_linux_mips64x.s
+++ b/src/runtime/sys_linux_mips64x.s
@@ -45,6 +45,7 @@
#define SYS_epoll_wait 5209
#define SYS_clock_gettime 5222
#define SYS_epoll_create1 5285
+#define SYS_brk 5012
TEXT runtime·exit(SB),NOSPLIT,$-8-4
MOVW code+0(FP), R4
@@ -426,3 +427,12 @@ TEXT runtime·closeonexec(SB),NOSPLIT,$-8
MOVV $SYS_fcntl, R2
SYSCALL
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$-8-8
+ // Implemented as brk(NULL).
+ MOVV $0, R4
+ MOVV $SYS_brk, R2
+ SYSCALL
+ MOVV R2, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_mipsx.s b/src/runtime/sys_linux_mipsx.s
index a9c556dd78..39bd731a4d 100644
--- a/src/runtime/sys_linux_mipsx.s
+++ b/src/runtime/sys_linux_mipsx.s
@@ -45,6 +45,7 @@
#define SYS_epoll_wait 4250
#define SYS_clock_gettime 4263
#define SYS_epoll_create1 4326
+#define SYS_brk 4045
TEXT runtime·exit(SB),NOSPLIT,$0-4
MOVW code+0(FP), R4
@@ -465,3 +466,12 @@ TEXT runtime·closeonexec(SB),NOSPLIT,$0-4
MOVW $SYS_fcntl, R2
SYSCALL
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT,$0-4
+ // Implemented as brk(NULL).
+ MOVW $0, R4
+ MOVW $SYS_brk, R2
+ SYSCALL
+ MOVW R2, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index ef7dab21b7..2b2aa61d06 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -21,6 +21,7 @@
#define SYS_close 6
#define SYS_getpid 20
#define SYS_kill 37
+#define SYS_brk 45
#define SYS_fcntl 55
#define SYS_gettimeofday 78
#define SYS_select 82 // always return -ENOSYS
@@ -422,3 +423,11 @@ TEXT runtime·closeonexec(SB),NOSPLIT|NOFRAME,$0
MOVD $1, R5 // FD_CLOEXEC
SYSCALL $SYS_fcntl
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT|NOFRAME,$0
+ // Implemented as brk(NULL).
+ MOVD $0, R3
+ SYSCALL $SYS_brk
+ MOVD R3, ret+0(FP)
+ RET
diff --git a/src/runtime/sys_linux_s390x.s b/src/runtime/sys_linux_s390x.s
index 2291718074..b8099e2553 100644
--- a/src/runtime/sys_linux_s390x.s
+++ b/src/runtime/sys_linux_s390x.s
@@ -16,6 +16,7 @@
#define SYS_close 6
#define SYS_getpid 20
#define SYS_kill 37
+#define SYS_brk 45
#define SYS_fcntl 55
#define SYS_gettimeofday 78
#define SYS_mmap 90
@@ -434,3 +435,12 @@ TEXT runtime·closeonexec(SB),NOSPLIT|NOFRAME,$0
MOVW $SYS_fcntl, R1
SYSCALL
RET
+
+// func sbrk0() uintptr
+TEXT runtime·sbrk0(SB),NOSPLIT|NOFRAME,$0-8
+ // Implemented as brk(NULL).
+ MOVD $0, R2
+ MOVW $SYS_brk, R1
+ SYSCALL
+ MOVD R2, ret+0(FP)
+ RET
generated by cgit v1.3-5-g9baa (git 2.53.0) at 2026-04-17 14:32:01 +0000