[PULL 28/38] linux-user: Introduce stubs for ELF AT_BASE_PLATFORM

[Laurent Vivier <laurent@vivier.eu>]

From: Jiaxun Yang <jiaxun.yang@flygoat.com>

AT_BASE_PLATFORM is a elf auxiliary vector pointing to a string
to pass some architecture information.
See getauxval(3) man-page.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220803103009.95972-2-jiaxun.yang@flygoat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/elfload.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index c7e3f1d47c16..581fbc858b48 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1776,6 +1776,10 @@ static inline void init_thread(struct target_pt_regs *regs,
 
 #endif /* TARGET_HEXAGON */
 
+#ifndef ELF_BASE_PLATFORM
+#define ELF_BASE_PLATFORM (NULL)
+#endif
+
 #ifndef ELF_PLATFORM
 #define ELF_PLATFORM (NULL)
 #endif
@@ -2220,8 +2224,8 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
     int i;
     abi_ulong u_rand_bytes;
     uint8_t k_rand_bytes[16];
-    abi_ulong u_platform;
-    const char *k_platform;
+    abi_ulong u_platform, u_base_platform;
+    const char *k_platform, *k_base_platform;
     const int n = sizeof(elf_addr_t);
 
     sp = p;
@@ -2243,6 +2247,22 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
         }
     }
 
+    u_base_platform = 0;
+    k_base_platform = ELF_BASE_PLATFORM;
+    if (k_base_platform) {
+        size_t len = strlen(k_base_platform) + 1;
+        if (STACK_GROWS_DOWN) {
+            sp -= (len + n - 1) & ~(n - 1);
+            u_base_platform = sp;
+            /* FIXME - check return value of memcpy_to_target() for failure */
+            memcpy_to_target(sp, k_base_platform, len);
+        } else {
+            memcpy_to_target(sp, k_base_platform, len);
+            u_base_platform = sp;
+            sp += len + 1;
+        }
+    }
+
     u_platform = 0;
     k_platform = ELF_PLATFORM;
     if (k_platform) {
@@ -2284,6 +2304,8 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
     }
 
     size = (DLINFO_ITEMS + 1) * 2;
+    if (k_base_platform)
+        size += 2;
     if (k_platform)
         size += 2;
 #ifdef DLINFO_ARCH_ITEMS
@@ -2361,6 +2383,9 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
     NEW_AUX_ENT(AT_HWCAP2, (abi_ulong) ELF_HWCAP2);
 #endif
 
+    if (u_base_platform) {
+        NEW_AUX_ENT(AT_BASE_PLATFORM, u_base_platform);
+    }
     if (u_platform) {
         NEW_AUX_ENT(AT_PLATFORM, u_platform);
     }
-- 
2.37.3