[PATCH] linux-user: Emulate the Anonymous: keyword in /proc/self/smaps

[Ilya Leoshkevich <iii@linux.ibm.com>]

Core dumps produced by gdb's gcore when connected to qemu's gdbstub
lack stack. The reason is that gdb includes only anonymous memory in
core dumps, which is distinguished by a non-0 Anonymous: value.

Consider the mappings with PAGE_ANON fully anonymous, and the mappings
without it fully non-anonymous.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 linux-user/syscall.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 95727a816ad..150be661dba 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8078,7 +8078,7 @@ static int open_self_cmdline(CPUArchState *cpu_env, int fd)
     return 0;
 }
 
-static void show_smaps(int fd, unsigned long size)
+static void show_smaps(int fd, unsigned long size, int flags)
 {
     unsigned long page_size_kb = TARGET_PAGE_SIZE >> 10;
     unsigned long size_kb = size >> 10;
@@ -8094,7 +8094,7 @@ static void show_smaps(int fd, unsigned long size)
                 "Private_Clean:         0 kB\n"
                 "Private_Dirty:         0 kB\n"
                 "Referenced:            0 kB\n"
-                "Anonymous:             0 kB\n"
+                "Anonymous:             %lu kB\n"
                 "LazyFree:              0 kB\n"
                 "AnonHugePages:         0 kB\n"
                 "ShmemPmdMapped:        0 kB\n"
@@ -8104,7 +8104,9 @@ static void show_smaps(int fd, unsigned long size)
                 "Swap:                  0 kB\n"
                 "SwapPss:               0 kB\n"
                 "Locked:                0 kB\n"
-                "THPeligible:    0\n", size_kb, page_size_kb, page_size_kb);
+                "THPeligible:    0\n",
+            size_kb, page_size_kb, page_size_kb,
+            (flags & PAGE_ANON) ? size_kb : 0);
 }
 
 static int open_self_maps_1(CPUArchState *cpu_env, int fd, bool smaps)
@@ -8155,7 +8157,7 @@ static int open_self_maps_1(CPUArchState *cpu_env, int fd, bool smaps)
                 dprintf(fd, "\n");
             }
             if (smaps) {
-                show_smaps(fd, max - min);
+                show_smaps(fd, max - min, flags);
                 dprintf(fd, "VmFlags:%s%s%s%s%s%s%s%s\n",
                         (flags & PAGE_READ) ? " rd" : "",
                         (flags & PAGE_WRITE_ORG) ? " wr" : "",
-- 
2.41.0