Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 2551e9b..b8cecb6 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -422,16 +422,22 @@
 })
 
 /* startup code */
+/*
+ * x86-64 System V ABI mandates:
+ * 1) %rsp must be 16-byte aligned right before the function call.
+ * 2) The deepest stack frame should be zero (the %rbp).
+ *
+ */
 asm(".section .text\n"
     ".global _start\n"
     "_start:\n"
     "pop %rdi\n"                // argc   (first arg, %rdi)
     "mov %rsp, %rsi\n"          // argv[] (second arg, %rsi)
     "lea 8(%rsi,%rdi,8),%rdx\n" // then a NULL then envp (third arg, %rdx)
-    "and $-16, %rsp\n"          // x86 ABI : esp must be 16-byte aligned when
-    "sub $8, %rsp\n"            // entering the callee
+    "xor %ebp, %ebp\n"          // zero the stack frame
+    "and $-16, %rsp\n"          // x86 ABI : esp must be 16-byte aligned before call
     "call main\n"               // main() returns the status code, we'll exit with it.
-    "movzb %al, %rdi\n"         // retrieve exit code from 8 lower bits
+    "mov %eax, %edi\n"          // retrieve exit code (32 bit)
     "mov $60, %rax\n"           // NR_exit == 60
     "syscall\n"                 // really exit
     "hlt\n"                     // ensure it does not return
@@ -600,20 +606,28 @@
 })
 
 /* startup code */
+/*
+ * i386 System V ABI mandates:
+ * 1) last pushed argument must be 16-byte aligned.
+ * 2) The deepest stack frame should be set to zero
+ *
+ */
 asm(".section .text\n"
     ".global _start\n"
     "_start:\n"
     "pop %eax\n"                // argc   (first arg, %eax)
     "mov %esp, %ebx\n"          // argv[] (second arg, %ebx)
     "lea 4(%ebx,%eax,4),%ecx\n" // then a NULL then envp (third arg, %ecx)
-    "and $-16, %esp\n"          // x86 ABI : esp must be 16-byte aligned when
+    "xor %ebp, %ebp\n"          // zero the stack frame
+    "and $-16, %esp\n"          // x86 ABI : esp must be 16-byte aligned before
+    "sub $4, %esp\n"            // the call instruction (args are aligned)
     "push %ecx\n"               // push all registers on the stack so that we
     "push %ebx\n"               // support both regparm and plain stack modes
     "push %eax\n"
     "call main\n"               // main() returns the status code in %eax
-    "movzbl %al, %ebx\n"        // retrieve exit code from lower 8 bits
-    "movl   $1, %eax\n"         // NR_exit == 1
-    "int    $0x80\n"            // exit now
+    "mov %eax, %ebx\n"          // retrieve exit code (32-bit int)
+    "movl $1, %eax\n"           // NR_exit == 1
+    "int $0x80\n"               // exit now
     "hlt\n"                     // ensure it does not
     "");
 
@@ -797,7 +811,6 @@
     "and %r3, %r1, $-8\n"         // AAPCS : sp must be 8-byte aligned in the
     "mov %sp, %r3\n"              //         callee, an bl doesn't push (lr=pc)
     "bl main\n"                   // main() returns the status code, we'll exit with it.
-    "and %r0, %r0, $0xff\n"       // limit exit code to 8 bits
     "movs r7, $1\n"               // NR_exit == 1
     "svc $0x00\n"
     "");
@@ -994,7 +1007,6 @@
     "add x2, x2, x1\n"            //           + argv
     "and sp, x1, -16\n"           // sp must be 16-byte aligned in the callee
     "bl main\n"                   // main() returns the status code, we'll exit with it.
-    "and x0, x0, 0xff\n"          // limit exit code to 8 bits
     "mov x8, 93\n"                // NR_exit == 93
     "svc #0\n"
     "");
@@ -1199,7 +1211,7 @@
     "addiu $sp,$sp,-16\n"         // the callee expects to save a0..a3 there!
     "jal main\n"                  // main() returns the status code, we'll exit with it.
     "nop\n"                       // delayed slot
-    "and $a0, $v0, 0xff\n"        // limit exit code to 8 bits
+    "move $a0, $v0\n"             // retrieve 32-bit exit code from v0
     "li $v0, 4001\n"              // NR_exit == 4001
     "syscall\n"
     ".end __start\n"
@@ -1397,7 +1409,6 @@
     "add   a2,a2,a1\n"           //             + argv
     "andi  sp,a1,-16\n"          // sp must be 16-byte aligned
     "call  main\n"               // main() returns the status code, we'll exit with it.
-    "andi  a0, a0, 0xff\n"       // limit exit code to 8 bits
     "li a7, 93\n"                // NR_exit == 93
     "ecall\n"
     "");