[glibc/release/2.34/master] Linux: Introduce __brk_call for invoking the brk system call

[glibc/release/2.34/master] Linux: Introduce __brk_call for invoking the brk system call

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=43d77ef9b87533221890423e491eed1b8ca81f0c

commit 43d77ef9b87533221890423e491eed1b8ca81f0c
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon May 16 18:41:43 2022 +0200

    Linux: Introduce __brk_call for invoking the brk system call
    
    Alpha and sparc can now use the generic implementation.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
    (cherry picked from commit b57ab258c1140bc45464b4b9908713e3e0ee35aa)

Diff:
---
 sysdeps/unix/sysv/linux/alpha/brk_call.h           | 28 +++++++++++++++++
 sysdeps/unix/sysv/linux/brk.c                      |  3 +-
 sysdeps/unix/sysv/linux/brk_call.h                 | 25 ++++++++++++++++
 .../sysv/linux/{alpha/brk.c => sparc/brk_call.h}   | 35 ++++++++++------------
 4 files changed, 71 insertions(+), 20 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/alpha/brk_call.h b/sysdeps/unix/sysv/linux/alpha/brk_call.h
new file mode 100644
index 0000000000..b8088cf13f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/alpha/brk_call.h
@@ -0,0 +1,28 @@
+/* Invoke the brk system call.  Alpha version.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+static inline void *
+__brk_call (void *addr)
+{
+  unsigned long int result = INTERNAL_SYSCALL_CALL (brk, addr);
+  if (result == -ENOMEM)
+    /* Mimic the default error reporting behavior.  */
+    return addr;
+  else
+    return (void *) result;
+}
diff --git a/sysdeps/unix/sysv/linux/brk.c b/sysdeps/unix/sysv/linux/brk.c
index 2d70d824fc..20b11c15ca 100644
--- a/sysdeps/unix/sysv/linux/brk.c
+++ b/sysdeps/unix/sysv/linux/brk.c
@@ -19,6 +19,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <sysdep.h>
+#include <brk_call.h>
 
 /* This must be initialized data because commons can't have aliases.  */
 void *__curbrk = 0;
@@ -33,7 +34,7 @@ weak_alias (__curbrk, ___brk_addr)
 int
 __brk (void *addr)
 {
-  __curbrk = (void *) INTERNAL_SYSCALL_CALL (brk, addr);
+  __curbrk = __brk_call (addr);
   if (__curbrk < addr)
     {
       __set_errno (ENOMEM);
diff --git a/sysdeps/unix/sysv/linux/brk_call.h b/sysdeps/unix/sysv/linux/brk_call.h
new file mode 100644
index 0000000000..72370c25d7
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/brk_call.h
@@ -0,0 +1,25 @@
+/* Invoke the brk system call.  Generic Linux version.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+static inline void *
+__brk_call (void *addr)
+{
+  /* The default implementation reports errors through an unchanged
+     break.  */
+  return (void *) INTERNAL_SYSCALL_CALL (brk, addr);
+}
diff --git a/sysdeps/unix/sysv/linux/alpha/brk.c b/sysdeps/unix/sysv/linux/sparc/brk_call.h
similarity index 61%
rename from sysdeps/unix/sysv/linux/alpha/brk.c
rename to sysdeps/unix/sysv/linux/sparc/brk_call.h
index 074c47e054..59ce521660 100644
--- a/sysdeps/unix/sysv/linux/alpha/brk.c
+++ b/sysdeps/unix/sysv/linux/sparc/brk_call.h
@@ -1,5 +1,5 @@
-/* Change data segment size.  Linux/Alpha.
-   Copyright (C) 2020-2021 Free Software Foundation, Inc.
+/* Invoke the brk system call.  Sparc version.
+   Copyright (C) 2022 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -16,23 +16,20 @@
    License along with the GNU C Library.  If not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
-#include <unistd.h>
-#include <sysdep.h>
+#ifdef __arch64__
+# define SYSCALL_NUM "0x6d"
+#else
+# define SYSCALL_NUM "0x10"
+#endif
 
-void *__curbrk = 0;
-
-int
-__brk (void *addr)
+static inline void *
+__brk_call (void *addr)
 {
-  /* Alpha brk returns -ENOMEM in case of failure.  */
-  __curbrk = (void *) INTERNAL_SYSCALL_CALL (brk, addr);
-  if ((unsigned long) __curbrk == -ENOMEM)
-    {
-      __set_errno (ENOMEM);
-      return -1;
-    }
-
-  return 0;
+  register long int g1 asm ("g1") = __NR_brk;
+  register long int o0 asm ("o0") = (long int) addr;
+  asm volatile ("ta " SYSCALL_NUM
+		: "=r"(o0)
+		: "r"(g1), "0"(o0)
+		: "cc");
+  return (void *) o0;
 }
-weak_alias (__brk, brk)