libc: Add ftruncate64 and improve 64-bit parameter syscall handling.

This patch improves the handling of 64-bit parameters in syscalls on ARM.
The ARM EABI mandates that 64-bit quantities be passed in even/odd register
pairs, which requires special treatment.

This allows us to simplify our implementations of pread() and pwrite()
and remove the C stubs for pread64() and pwrite64().

Also add ftruncate64() to <unistd.h>

Change-Id: I407e2fd223ba0093dd2d0b04c6152fadfc9ce3ef

Bug 3107933

libc/arch-arm/syscalls.mk

@@ -41,8 +41,8 @@ syscall_src += arch-arm/syscalls/sigaltstack.S
 syscall_src += arch-arm/syscalls/acct.S
 syscall_src += arch-arm/syscalls/read.S
 syscall_src += arch-arm/syscalls/write.S
-syscall_src += arch-arm/syscalls/__pread64.S
-syscall_src += arch-arm/syscalls/__pwrite64.S
+syscall_src += arch-arm/syscalls/pread64.S
+syscall_src += arch-arm/syscalls/pwrite64.S
 syscall_src += arch-arm/syscalls/__open.S
 syscall_src += arch-arm/syscalls/__openat.S
 syscall_src += arch-arm/syscalls/close.S
@@ -70,6 +70,7 @@ syscall_src += arch-arm/syscalls/pipe2.S
 syscall_src += arch-arm/syscalls/dup2.S
 syscall_src += arch-arm/syscalls/select.S
 syscall_src += arch-arm/syscalls/ftruncate.S
+syscall_src += arch-arm/syscalls/ftruncate64.S
 syscall_src += arch-arm/syscalls/getdents.S
 syscall_src += arch-arm/syscalls/fsync.S
 syscall_src += arch-arm/syscalls/fdatasync.S

libc/arch-arm/syscalls/ftruncate64.S

@@ -0,0 +1,19 @@
+/* autogenerated by gensyscalls.py */
+#include <sys/linux-syscalls.h>
+
+    .text
+    .type ftruncate64, #function
+    .globl ftruncate64
+    .align 4
+    .fnstart
+
+ftruncate64:
+    .save   {r4, r7}
+    stmfd   sp!, {r4, r7}
+    ldr     r7, =__NR_ftruncate64
+    swi     #0
+    ldmfd   sp!, {r4, r7}
+    movs    r0, r0
+    bxpl    lr
+    b       __set_syscall_errno
+    .fnend

libc/arch-arm/syscalls/pread64.S

@@ -2,12 +2,12 @@
 #include <sys/linux-syscalls.h>
 
     .text
-    .type __pread64, #function
-    .globl __pread64
+    .type pread64, #function
+    .globl pread64
     .align 4
     .fnstart
 
-__pread64:
+pread64:
     mov     ip, sp
     .save   {r4, r5, r6, r7}
     stmfd   sp!, {r4, r5, r6, r7}

libc/arch-arm/syscalls/pwrite64.S

@@ -2,12 +2,12 @@
 #include <sys/linux-syscalls.h>
 
     .text
-    .type __pwrite64, #function
-    .globl __pwrite64
+    .type pwrite64, #function
+    .globl pwrite64
     .align 4
     .fnstart
 
-__pwrite64:
+pwrite64:
     mov     ip, sp
     .save   {r4, r5, r6, r7}
     stmfd   sp!, {r4, r5, r6, r7}