From 969174e155d4bddcec7a2c6c1f4e7e4d3c293f93 Mon Sep 17 00:00:00 2001
From: Justine Tunney <jtunney@gmail.com>
Date: Sat, 4 Sep 2021 00:58:21 -0700
Subject: [PATCH] Add APE interpreter example (#263)
---
examples/examples.mk | 12 +++++-
examples/loader.c | 98 ++++++++++++++++++++++++++++++++++++++++++++
examples/loader.lds | 66 +++++++++++++++++++++++++++++
libc/elf/def.h | 6 +--
libc/linux/execve.h | 16 ++++++++
libc/linux/mmap.h | 14 +++----
libc/str/wmemset.c | 12 ++++--
7 files changed, 210 insertions(+), 14 deletions(-)
create mode 100644 examples/loader.c
create mode 100644 examples/loader.lds
create mode 100644 libc/linux/execve.h
diff --git a/examples/examples.mk b/examples/examples.mk
index f904ba104..006ce46f6 100644
--- a/examples/examples.mk
+++ b/examples/examples.mk
@@ -30,7 +30,8 @@ EXAMPLES_COMS = \
EXAMPLES_BINS = \
$(EXAMPLES_COMS) \
- $(EXAMPLES_COMS:%=%.dbg)
+ $(EXAMPLES_COMS:%=%.dbg) \
+ o/$(MODE)/examples/loader.elf
EXAMPLES_DIRECTDEPS = \
DSP_CORE \
@@ -130,6 +131,15 @@ o/$(MODE)/examples/nesemu1.com.dbg: \
$(APE)
@$(APELINK)
+o/$(MODE)/examples/loader.o: \
+ OVERRIDE_CCFLAGS += \
+ -fno-record-gcc-switches
+
+o/$(MODE)/examples/loader.elf: \
+ o/$(MODE)/examples/loader.o \
+ examples/loader.lds
+ @$(ELFLINK) -s -z max-page-size=0x10
+
$(EXAMPLES_OBJS): examples/examples.mk
usr/share/dict/words: usr/share/dict/words.gz
diff --git a/examples/loader.c b/examples/loader.c
new file mode 100644
index 000000000..382c89e51
--- /dev/null
+++ b/examples/loader.c
@@ -0,0 +1,98 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived │
+│ all copyright and related or neighboring rights to this file, │
+│ as it is written in the following disclaimers: │
+│ • http://unlicense.org/ │
+│ • http://creativecommons.org/publicdomain/zero/1.0/ │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include "libc/bits/bits.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/stat.h"
+#include "libc/elf/def.h"
+#include "libc/elf/struct/ehdr.h"
+#include "libc/elf/struct/phdr.h"
+#include "libc/linux/close.h"
+#include "libc/linux/exit.h"
+#include "libc/linux/fstat.h"
+#include "libc/linux/mmap.h"
+#include "libc/linux/open.h"
+
+/**
+ * @fileoverview 704-byte APE executing payload for Linux, e.g.
+ *
+ * m=tiny
+ * make -j8 MODE=$m o/$m/examples
+ * o/$m/examples/loader.elf o/$m/examples/printargs.com
+ *
+ * @note this can probably be used as a binfmt_misc interpreter
+ */
+
+#define O_RDONLY 0
+#define PROT_READ 1
+#define PROT_WRITE 2
+#define PROT_EXEC 4
+#define MAP_SHARED 1
+#define MAP_PRIVATE 2
+#define MAP_FIXED 16
+#define MAP_ANONYMOUS 32
+
+asm(".globl\t_start\n\t"
+ "_start:\n\t"
+ "mov\t%rsp,%rdi\n\t"
+ "jmp\tloader");
+
+static noasan noubsan void spawn(long *sp, char *b) {
+ struct Elf64_Ehdr *e;
+ struct Elf64_Phdr *h;
+ e = (void *)b;
+ h = (void *)(b + e->e_phoff);
+ if (LinuxMmap((void *)(h[1].p_vaddr + h[1].p_filesz),
+ h[1].p_memsz - h[1].p_filesz, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1, 0) > 0) {
+ sp[1] = sp[0] - 1;
+ asm volatile("mov\t%2,%%rsp\n\t"
+ "jmpq\t*%1"
+ : /* no outputs */
+ : "D"(0), "S"((void *)e->e_entry), "d"(sp + 1)
+ : "memory");
+ unreachable;
+ }
+}
+
+noasan noubsan void loader(long *sp) {
+ struct stat st;
+ int c, i, fd, argc;
+ char *b, *p, *q, **argv;
+ argc = *sp;
+ argv = (char **)(sp + 1);
+ if (argc > 1 && (fd = LinuxOpen(argv[1], O_RDONLY, 0)) >= 0 &&
+ !LinuxFstat(fd, &st) &&
+ (b = (char *)LinuxMmap((void *)0x400000, st.st_size,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_PRIVATE | MAP_FIXED, fd, 0)) > 0) {
+ LinuxClose(fd);
+ if (READ32LE(b) == READ32LE("\177ELF")) {
+ spawn(sp, b);
+ } else {
+ for (p = b; p < b + st.st_size; ++p) {
+ if (READ64LE(p) == READ64LE("printf '")) {
+ for (q = b, p += 8; (c = *p++) != '\'';) {
+ if (c == '\\') {
+ c = *p++ - '0';
+ if ('0' <= *p && *p <= '7') c *= 8, c += *p++ - '0';
+ if ('0' <= *p && *p <= '7') c *= 8, c += *p++ - '0';
+ }
+ *q++ = c;
+ }
+ if (READ32LE(b) == READ32LE("\177ELF")) {
+ spawn(sp, b);
+ }
+ break;
+ }
+ }
+ }
+ }
+ LinuxExit(127);
+}
diff --git a/examples/loader.lds b/examples/loader.lds
new file mode 100644
index 000000000..6e6fb1025
--- /dev/null
+++ b/examples/loader.lds
@@ -0,0 +1,66 @@
+/*-*- mode: ld-script; indent-tabs-mode: nil; tab-width: 2; coding: utf-8 -*-│
+│vi: set et sts=2 tw=2 fenc=utf-8 :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney │
+│ │
+│ Permission to use, copy, modify, and/or distribute this software for │
+│ any purpose with or without fee is hereby granted, provided that the │
+│ above copyright notice and this permission notice appear in all copies. │
+│ │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
+│ PERFORMANCE OF THIS SOFTWARE. │
+╚─────────────────────────────────────────────────────────────────────────────*/
+
+ENTRY(_start)
+
+SECTIONS {
+
+ . = 0x200000 + SIZEOF_HEADERS;
+
+ .text : {
+ *(.text .text.*)
+ *(.rodata .rodata.*)
+ *(.data .data.*)
+ *(.bss .bss.*)
+ }
+
+ .gnu_debuglink 0 : { *(.gnu_debuglink) }
+ .stab 0 : { *(.stab) }
+ .stabstr 0 : { *(.stabstr) }
+ .stab.excl 0 : { *(.stab.excl) }
+ .stab.exclstr 0 : { *(.stab.exclstr) }
+ .stab.index 0 : { *(.stab.index) }
+ .stab.indexstr 0 : { *(.stab.indexstr) }
+ .debug 0 : { *(.debug) }
+ .line 0 : { *(.line) }
+ .debug_srcinfo 0 : { *(.debug_srcinfo) }
+ .debug_sfnames 0 : { *(.debug_sfnames) }
+ .debug_aranges 0 : { *(.debug_aranges) }
+ .debug_pubnames 0 : { *(.debug_pubnames) }
+ .debug_info 0 : { *(.debug_info .gnu.linkonce.wi.*) }
+ .debug_abbrev 0 : { *(.debug_abbrev) }
+ .debug_line 0 : { *(.debug_line .debug_line.* .debug_line_end ) }
+ .debug_frame 0 : { *(.debug_frame) }
+ .debug_str 0 : { *(.debug_str) }
+ .debug_loc 0 : { *(.debug_loc) }
+ .debug_macinfo 0 : { *(.debug_macinfo) }
+ .debug_weaknames 0 : { *(.debug_weaknames) }
+ .debug_funcnames 0 : { *(.debug_funcnames) }
+ .debug_typenames 0 : { *(.debug_typenames) }
+ .debug_varnames 0 : { *(.debug_varnames) }
+ .debug_pubtypes 0 : { *(.debug_pubtypes) }
+ .debug_ranges 0 : { *(.debug_ranges) }
+ .debug_macro 0 : { *(.debug_macro) }
+ .debug_addr 0 : { *(.debug_addr) }
+ .gnu.attributes 0 : { KEEP(*(.gnu.attributes)) }
+
+ /DISCARD/ : {
+ *(.*)
+ }
+}
diff --git a/libc/elf/def.h b/libc/elf/def.h
index e5362ca22..b282babcb 100644
--- a/libc/elf/def.h
+++ b/libc/elf/def.h
@@ -123,9 +123,9 @@
#define PN_XNUM 0xffff
-#define PF_X (1 << 0)
-#define PF_W (1 << 1)
-#define PF_R (1 << 2)
+#define PF_X 1
+#define PF_W 2
+#define PF_R 4
#define PF_MASKOS 0x0ff00000
#define PF_MASKPROC 0xf0000000
diff --git a/libc/linux/execve.h b/libc/linux/execve.h
new file mode 100644
index 000000000..5ac2d6e7e
--- /dev/null
+++ b/libc/linux/execve.h
@@ -0,0 +1,16 @@
+#ifndef COSMOPOLITAN_LIBC_LINUX_EXECVE_H_
+#define COSMOPOLITAN_LIBC_LINUX_EXECVE_H_
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+
+forceinline long LinuxExecve(const char *program, char *const argv[],
+ char *const envp[]) {
+ long rc;
+ asm volatile("syscall"
+ : "=a"(rc)
+ : "0"(59), "D"(program), "S"(argv), "d"(envp)
+ : "rcx", "r11", "memory");
+ return rc;
+}
+
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_LINUX_EXECVE_H_ */
diff --git a/libc/linux/mmap.h b/libc/linux/mmap.h
index a23fdfafe..e1ba56b63 100644
--- a/libc/linux/mmap.h
+++ b/libc/linux/mmap.h
@@ -5,14 +5,14 @@
forceinline long LinuxMmap(void *addr, size_t size, long prot, long flags,
long fd, long off) {
long rc;
- asm volatile("mov\t%5,%%r10\n\t"
- "mov\t%6,%%r8\n\t"
- "mov\t%7,%%r9\n\t"
- "syscall"
+ register long flags_ asm("r10") = flags;
+ register long fd_ asm("r8") = fd;
+ register long off_ asm("r9") = off;
+ asm volatile("syscall"
: "=a"(rc)
- : "0"(9), "D"(addr), "S"(size), "d"(prot), "g"(flags), "g"(fd),
- "g"(off)
- : "rcx", "r8", "r9", "r10", "r11", "memory");
+ : "0"(9), "D"(addr), "S"(size), "d"(prot), "r"(flags_), "r"(fd_),
+ "r"(off_)
+ : "rcx", "r11", "memory");
return rc;
}
diff --git a/libc/str/wmemset.c b/libc/str/wmemset.c
index a79ecff2f..950458a16 100644
--- a/libc/str/wmemset.c
+++ b/libc/str/wmemset.c
@@ -23,9 +23,15 @@
* @asyncsignalsafe
*/
wchar_t *wmemset(wchar_t *p, wchar_t c, size_t n) {
- size_t i;
- for (i = 0; i < n; ++i) {
- p[i] = c;
+ size_t i = 0;
+ if (n >= 4) {
+ wchar_t v __attribute__((__vector_size__(16))) = {c, c, c, c};
+ do {
+ __builtin_memcpy(p + i, &v, 16);
+ } while ((i += 4) + 4 <= n);
+ }
+ while (i < n) {
+ p[i++] = c;
}
return p;
}