From 557dbbac8e6a344d44fedff75e16008fa8a5ffb7 Mon Sep 17 00:00:00 2001
From: YunQiang Su <yunqiang.su@cipunited.com>
Date: Wed, 17 Jan 2024 15:11:33 +0800
Subject: [PATCH] Sanitizer/MIPS: Use $t9 for preemptible function call

Currently, almost all of the shared libraries of MIPS, rely on $t9
to get the address of current function, instead of PCREL instructions,
even on MIPSr6. So we have to set $t9 properly.

To get the address of preemptible function, we need the help of GOT.
MIPS/O32 has .cpload, which can help to generate 3 instructions to get GOT.
For __mips64, we can get GOT by:

lui $t8, %hi(%neg(%gp_rel(SANITIZER_STRINGIFY(TRAMPOLINE(func)))))
daddu $t8, $t8, $t9
daddiu $t8, $t8, %hi(%neg(%gp_rel(SANITIZER_STRINGIFY(TRAMPOLINE(func)))))

And then get the address of __interceptor_func, and jump to it

ld $t9, %got_disp(_interceptor" SANITIZER_STRINGIFY(func) ")($t8)
jr $t9

Upstream-Commit: 0a64367a72f1634321f5051221f05f2f364bd882

libsanitizer

	* interception/interception.h (substitution_##func_name):
	Use macro C_ASM_TAIL_CALL.
	* sanitizer_common/sanitizer_asm.h: Define C_ASM_TAIL_CALL
	for MIPS with help of t9.
---
 libsanitizer/interception/interception.h      |  5 ++--
 libsanitizer/sanitizer_common/sanitizer_asm.h | 23 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/libsanitizer/interception/interception.h b/libsanitizer/interception/interception.h
index 9d8b60b2eef..58e969378a9 100644
--- a/libsanitizer/interception/interception.h
+++ b/libsanitizer/interception/interception.h
@@ -205,8 +205,9 @@ const interpose_substitution substitution_##func_name[]             \
          ASM_TYPE_FUNCTION_STR "\n"                                            \
        SANITIZER_STRINGIFY(TRAMPOLINE(func)) ":\n"                             \
        SANITIZER_STRINGIFY(CFI_STARTPROC) "\n"                                 \
-       SANITIZER_STRINGIFY(ASM_TAIL_CALL) " __interceptor_"                    \
-         SANITIZER_STRINGIFY(ASM_PREEMPTIBLE_SYM(func)) "\n"                   \
+       C_ASM_TAIL_CALL(SANITIZER_STRINGIFY(TRAMPOLINE(func)),                  \
+                       "__interceptor_"                                        \
+                         SANITIZER_STRINGIFY(ASM_PREEMPTIBLE_SYM(func))) "\n"  \
        SANITIZER_STRINGIFY(CFI_ENDPROC) "\n"                                   \
        ".size  " SANITIZER_STRINGIFY(TRAMPOLINE(func)) ", "                    \
             ".-" SANITIZER_STRINGIFY(TRAMPOLINE(func)) "\n"                    \
diff --git a/libsanitizer/sanitizer_common/sanitizer_asm.h b/libsanitizer/sanitizer_common/sanitizer_asm.h
index bbb18cfbdf1..3af66a4e449 100644
--- a/libsanitizer/sanitizer_common/sanitizer_asm.h
+++ b/libsanitizer/sanitizer_common/sanitizer_asm.h
@@ -53,6 +53,29 @@
 # define ASM_TAIL_CALL tail
 #endif
 
+// Currently, almost all of the shared libraries rely on the value of
+// $t9 to get the address of current function, instead of PCREL, even
+// on MIPSr6. To be compatiable with them, we have to set $t9 properly.
+// MIPS uses GOT to get the address of preemptible functions.
+#if defined(__mips64)
+#  define C_ASM_TAIL_CALL(t_func, i_func)                       \
+    "lui $t8, %hi(%neg(%gp_rel(" t_func ")))\n"                 \
+    "daddu $t8, $t8, $t9\n"                                     \
+    "daddiu $t8, $t8, %lo(%neg(%gp_rel(" t_func ")))\n"         \
+    "ld $t9, %got_disp(" i_func ")($t8)\n"                      \
+    "jr $t9\n"
+#elif defined(__mips__)
+#  define C_ASM_TAIL_CALL(t_func, i_func)                       \
+    ".set    noreorder\n"                                       \
+    ".cpload $t9\n"                                             \
+    ".set    reorder\n"                                         \
+    "lw $t9, %got(" i_func ")($gp)\n"                           \
+    "jr $t9\n"
+#elif defined(ASM_TAIL_CALL)
+#  define C_ASM_TAIL_CALL(t_func, i_func)                       \
+    SANITIZER_STRINGIFY(ASM_TAIL_CALL) " " i_func
+#endif
+
 #if defined(__ELF__) && defined(__x86_64__) || defined(__i386__) || \
     defined(__riscv)
 # define ASM_PREEMPTIBLE_SYM(sym) sym@plt