[MIPS] Add seccomp bpf support

sandbox/linux/seccomp-bpf/linux_seccomp.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_LINUX_SECCOMP_H__
 #define SANDBOX_LINUX_SECCOMP_BPF_LINUX_SECCOMP_H__
 
 // The Seccomp2 kernel ABI is not part of older versions of glibc.
 // As we can't break compilation with these versions of the library,
 // we explicitly define all missing symbols.
 // If we ever decide that we can now rely on system headers, the following
 // include files should be enabled:
 // #include <linux/audit.h>
 // #include <linux/seccomp.h>
 
 #include <asm/unistd.h>
 #include <linux/filter.h>
 
 // For audit.h
 #ifndef EM_ARM
 #define EM_ARM    40
 #endif
 #ifndef EM_386
 #define EM_386    3
 #endif
 #ifndef EM_X86_64
 #define EM_X86_64 62
 #endif
+#ifndef EM_MIPS
+#define EM_MIPS   8
+#endif
 
 #ifndef __AUDIT_ARCH_64BIT
 #define __AUDIT_ARCH_64BIT 0x80000000
 #endif
 #ifndef __AUDIT_ARCH_LE
 #define __AUDIT_ARCH_LE    0x40000000
 #endif
 #ifndef AUDIT_ARCH_ARM
 #define AUDIT_ARCH_ARM    (EM_ARM|__AUDIT_ARCH_LE)
 #endif
 #ifndef AUDIT_ARCH_I386
 #define AUDIT_ARCH_I386   (EM_386|__AUDIT_ARCH_LE)
 #endif
 #ifndef AUDIT_ARCH_X86_64
 #define AUDIT_ARCH_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
 #endif
+#ifndef AUDIT_ARCH_MIPSEL
+#define AUDIT_ARCH_MIPSEL    (EM_MIPS|__AUDIT_ARCH_LE)
+#endif
 
 // For prctl.h
 #ifndef PR_SET_SECCOMP
 #define PR_SET_SECCOMP               22
 #define PR_GET_SECCOMP               21
 #endif
 #ifndef PR_SET_NO_NEW_PRIVS
 #define PR_SET_NO_NEW_PRIVS          38
 #define PR_GET_NO_NEW_PRIVS          39
 #endif
@@ skipping 127 matching lines @@
 #define SECCOMP_ARCH_IDX        (offsetof(struct arch_seccomp_data, arch))
 #define SECCOMP_IP_MSB_IDX      (offsetof(struct arch_seccomp_data,           \
                                           instruction_pointer) + 4)
 #define SECCOMP_IP_LSB_IDX      (offsetof(struct arch_seccomp_data,           \
                                           instruction_pointer) + 0)
 #define SECCOMP_ARG_MSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
                                  8*(nr) + 4)
 #define SECCOMP_ARG_LSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
                                  8*(nr) + 0)
 
+#elif defined(__mips__) && (_MIPS_SIM == _MIPS_SIM_ABI32)
+#define MIN_SYSCALL         __NR_O32_Linux
+#define MAX_PUBLIC_SYSCALL  (MIN_SYSCALL + __NR_Linux_syscalls)
+#define MAX_SYSCALL         MAX_PUBLIC_SYSCALL
+#define SECCOMP_ARCH        AUDIT_ARCH_MIPSEL
+
+// MIPS sigcontext_t is different from i386/x86_64 and ARM.
+// See </arch/mips/include/uapi/asm/sigcontext.h> in the Linux kernel.
+#define SECCOMP_REG(_ctx, _reg) ((_ctx)->uc_mcontext.gregs[_reg])
+// Based on MIPS o32 ABI syscall convention.
+// On MIPS, when indirect syscall is being made (syscall(__NR_foo)),
+// real identificator (__NR_foo) is not in v0, but in a0
+#define SECCOMP_RESULT(_ctx)    SECCOMP_REG(_ctx, 2)
+#define SECCOMP_SYSCALL(_ctx)   SECCOMP_REG(_ctx, 2)
+#define SECCOMP_IP(_ctx)        (_ctx)->uc_mcontext.pc
+#define SECCOMP_PARM1(_ctx)     SECCOMP_REG(_ctx, 4)
+#define SECCOMP_PARM2(_ctx)     SECCOMP_REG(_ctx, 5)
+#define SECCOMP_PARM3(_ctx)     SECCOMP_REG(_ctx, 6)
+#define SECCOMP_PARM4(_ctx)     SECCOMP_REG(_ctx, 7)
+// Only the first 4 arguments of syscall are in registers.
+// The rest are on the stack.
+#define SECCOMP_PARM5(_ctx)     (long int)(*((intptr_t*)SECCOMP_REG(_ctx, 29)+4))

[jln (very slow on Chromium), 2014/05/02 20:42:04]

Nit: wrap

[nedeljko, 2014/05/07 15:40:05]

Done.

+#define SECCOMP_PARM6(_ctx)     (long int)(*((intptr_t*)SECCOMP_REG(_ctx, 29)+5))

[jln (very slow on Chromium), 2014/05/02 20:42:04]

Nit: wrap

[nedeljko, 2014/05/07 15:40:05]

Done.

+#define SECCOMP_NR_IDX          (offsetof(struct arch_seccomp_data, nr))
+#define SECCOMP_ARCH_IDX        (offsetof(struct arch_seccomp_data, arch))
+#define SECCOMP_IP_MSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 4)
+#define SECCOMP_IP_LSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 0)
+#define SECCOMP_ARG_MSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 4)
+#define SECCOMP_ARG_LSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 0)
+
 #else
 #error Unsupported target platform
 
 #endif
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_LINUX_SECCOMP_H__