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From:   Zhangjin Wu <falcon@tinylab.org>
To:     w@1wt.eu
Cc:     arnd@arndb.de, falcon@tinylab.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, thomas@t-8ch.de
Subject: [PATCH v4 12/18] tools/nolibc: loongarch: shrink _start with _start_c
Date:   Sun, 16 Jul 2023 02:30:02 +0800
Message-Id: <774441edc010cc55f11546635dc04fc5604dc29a.1689444638.git.falcon@tinylab.org>
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move most of the _start operations to _start_c(), include the
stackprotector initialization.

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/include/nolibc/arch-loongarch.h | 44 +++------------------------
 1 file changed, 4 insertions(+), 40 deletions(-)

diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h
index 590155a4e543..bf98f6220195 100644
--- a/tools/include/nolibc/arch-loongarch.h
+++ b/tools/include/nolibc/arch-loongarch.h
@@ -8,6 +8,7 @@
 #define _NOLIBC_ARCH_LOONGARCH_H
 
 #include "compiler.h"
+#include "crt.h"
 
 /* Syscalls for LoongArch :
  *   - stack is 16-byte aligned
@@ -143,26 +144,9 @@
 	_arg1;                                                                \
 })
 
-char **environ __attribute__((weak));
-const unsigned long *_auxv __attribute__((weak));
-
 #if __loongarch_grlen == 32
-#define LONGLOG      "2"
-#define SZREG        "4"
-#define REG_L        "ld.w"
-#define LONG_S       "st.w"
-#define LONG_ADD     "add.w"
-#define LONG_ADDI    "addi.w"
-#define LONG_SLL     "slli.w"
 #define LONG_BSTRINS "bstrins.w"
 #else /* __loongarch_grlen == 64 */
-#define LONGLOG      "3"
-#define SZREG        "8"
-#define REG_L        "ld.d"
-#define LONG_S       "st.d"
-#define LONG_ADD     "add.d"
-#define LONG_ADDI    "addi.d"
-#define LONG_SLL     "slli.d"
 #define LONG_BSTRINS "bstrins.d"
 #endif
 
@@ -170,29 +154,9 @@ const unsigned long *_auxv __attribute__((weak));
 void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
 {
 	__asm__ volatile (
-#ifdef _NOLIBC_STACKPROTECTOR
-		"bl __stack_chk_init\n"               /* initialize stack protector                          */
-#endif
-		REG_L        " $a0, $sp, 0\n"         /* argc (a0) was in the stack                          */
-		LONG_ADDI    " $a1, $sp, "SZREG"\n"   /* argv (a1) = sp + SZREG                              */
-		LONG_SLL     " $a2, $a0, "LONGLOG"\n" /* envp (a2) = SZREG*argc ...                          */
-		LONG_ADDI    " $a2, $a2, "SZREG"\n"   /*             + SZREG (skip null)                     */
-		LONG_ADD     " $a2, $a2, $a1\n"       /*             + argv                                  */
-
-		"move          $a3, $a2\n"            /* iterate a3 over envp to find auxv (after NULL)      */
-		"0:\n"                                /* do {                                                */
-		REG_L        " $a4, $a3, 0\n"         /*   a4 = *a3;                                         */
-		LONG_ADDI    " $a3, $a3, "SZREG"\n"   /*   a3 += sizeof(void*);                              */
-		"bne           $a4, $zero, 0b\n"      /* } while (a4);                                       */
-		"la.pcrel      $a4, _auxv\n"          /* a4 = &_auxv                                         */
-		LONG_S       " $a3, $a4, 0\n"         /* store a3 into _auxv                                 */
-
-		"la.pcrel      $a3, environ\n"        /* a3 = &environ                                       */
-		LONG_S       " $a2, $a3, 0\n"         /* store envp(a2) into environ                         */
-		LONG_BSTRINS " $sp, $zero, 3, 0\n"    /* sp must be 16-byte aligned                          */
-		"bl            main\n"                /* main() returns the status code, we'll exit with it. */
-		"li.w          $a7, 93\n"             /* NR_exit == 93                                       */
-		"syscall       0\n"
+		"move          $a0, $sp\n"         /* save stack pointer to $a0, as arg1 of _start_c */
+		LONG_BSTRINS " $sp, $zero, 3, 0\n" /* $sp must be 16-byte aligned                    */
+		"bl            _start_c\n"         /* transfer to c runtime                          */
 	);
 	__builtin_unreachable();
 }
-- 
2.25.1