[PATCH v4 1/4] linux-user: Create vdso_sigreturn_region_{start,end}

[Richard Henderson]

These variables will be populated from the vdso, and used
for detecting whether we are executing the sigreturn.

Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
 linux-user/loader.h            | 2 ++
 linux-user/signal-common.h     | 2 ++
 linux-user/elfload.c           | 5 +++++
 linux-user/gen-vdso.c          | 6 ++++++
 linux-user/signal.c            | 2 ++
 linux-user/gen-vdso-elfn.c.inc | 7 +++++--
 6 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/linux-user/loader.h b/linux-user/loader.h
index e42b8fa1e3..da9ad28db5 100644
--- a/linux-user/loader.h
+++ b/linux-user/loader.h
@@ -117,6 +117,8 @@ typedef struct {
     unsigned reloc_count;
     unsigned sigreturn_ofs;
     unsigned rt_sigreturn_ofs;
+    unsigned sigreturn_region_start_ofs;
+    unsigned sigreturn_region_end_ofs;
 } VdsoImageInfo;
 
 /* Note that both Elf32_Word and Elf64_Word are uint32_t. */
diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
index 196d2406f8..0b04868727 100644
--- a/linux-user/signal-common.h
+++ b/linux-user/signal-common.h
@@ -25,6 +25,8 @@
 /* Fallback addresses into sigtramp page. */
 extern abi_ulong default_sigreturn;
 extern abi_ulong default_rt_sigreturn;
+extern abi_ulong vdso_sigreturn_region_start;
+extern abi_ulong vdso_sigreturn_region_end;
 
 void setup_sigtramp(abi_ulong tramp_page);
 
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 26c090c95d..28f0909d1a 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1659,6 +1659,11 @@ static void load_elf_vdso(struct image_info *info, const 
VdsoImageInfo *vdso)
     if (vdso->rt_sigreturn_ofs) {
         default_rt_sigreturn = load_addr + vdso->rt_sigreturn_ofs;
     }
+    if (vdso->sigreturn_region_start_ofs) {
+        vdso_sigreturn_region_start =
+            load_addr + vdso->sigreturn_region_start_ofs;
+        vdso_sigreturn_region_end = load_addr + vdso->sigreturn_region_end_ofs;
+    }
 
     /* Remove write from VDSO segment. */
     target_mprotect(info->start_data, info->end_data - info->start_data,
diff --git a/linux-user/gen-vdso.c b/linux-user/gen-vdso.c
index aeaa927db8..d6a2cdaa83 100644
--- a/linux-user/gen-vdso.c
+++ b/linux-user/gen-vdso.c
@@ -36,6 +36,8 @@ static const char *rt_sigreturn_sym;
 
 static unsigned sigreturn_addr;
 static unsigned rt_sigreturn_addr;
+static unsigned sigreturn_region_start_addr;
+static unsigned sigreturn_region_end_addr;
 
 #define N 32
 #define elfN(x)  elf32_##x
@@ -215,6 +217,10 @@ int main(int argc, char **argv)
     fprintf(outf, "    .reloc_count = ARRAY_SIZE(%s_relocs),\n", prefix);
     fprintf(outf, "    .sigreturn_ofs = 0x%x,\n", sigreturn_addr);
     fprintf(outf, "    .rt_sigreturn_ofs = 0x%x,\n", rt_sigreturn_addr);
+    fprintf(outf, "    .sigreturn_region_start_ofs = 0x%x,\n",
+            sigreturn_region_start_addr);
+    fprintf(outf, "    .sigreturn_region_end_ofs = 0x%x,\n",
+            sigreturn_region_end_addr);
     fprintf(outf, "};\n");
 
     ret = EXIT_SUCCESS;
diff --git a/linux-user/signal.c b/linux-user/signal.c
index cd0e7398aa..804096bd44 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -50,6 +50,8 @@ static void host_signal_handler(int host_signum, siginfo_t 
*info,
 /* Fallback addresses into sigtramp page. */
 abi_ulong default_sigreturn;
 abi_ulong default_rt_sigreturn;
+abi_ulong vdso_sigreturn_region_start;
+abi_ulong vdso_sigreturn_region_end;
 
 /*
  * System includes define _NSIG as SIGRTMAX + 1, but qemu (like the kernel)
diff --git a/linux-user/gen-vdso-elfn.c.inc b/linux-user/gen-vdso-elfn.c.inc
index b47019e136..c2677a146c 100644
--- a/linux-user/gen-vdso-elfn.c.inc
+++ b/linux-user/gen-vdso-elfn.c.inc
@@ -84,9 +84,12 @@ static void elfN(search_symtab)(ElfN(Shdr) *shdr, unsigned 
sym_idx,
 
         if (sigreturn_sym && strcmp(sigreturn_sym, name) == 0) {
             sigreturn_addr = sym.st_value;
-        }
-        if (rt_sigreturn_sym && strcmp(rt_sigreturn_sym, name) == 0) {
+        } else if (rt_sigreturn_sym && strcmp(rt_sigreturn_sym, name) == 0) {
             rt_sigreturn_addr = sym.st_value;
+        } else if (strcmp("sigreturn_region_start", name) == 0) {
+            sigreturn_region_start_addr = sym.st_value;
+        } else if (strcmp("sigreturn_region_end", name) == 0) {
+            sigreturn_region_end_addr = sym.st_value;
         }
     }
 }
-- 
2.43.0