truss: improved support for decoding compat32 arguments
Currently running `truss -a -e` does not decode any
argument values for freebsd32_* syscalls (open/readlink/etc.)
This change checks whether a syscall starts with freebsd{32,64}_ and if
so strips that prefix when looking up the syscall information. To ensure
that the truss logs include the real syscall name we create a copy of
the syscall information struct with the updated.
The other problem is that when reading string array values, truss
naively iterates over an array of char* and fetches the pointer value.
This will result in arguments not being loaded if the pointer is not
aligned to sizeof(void*), which can happens in the compat32 case. If it
happens to be aligned, we would end up printing every other value.
To fix this problem, this changes adds a pointer_size member to the
procabi struct and uses that to correctly read indirect arguments
as 64/32 bit addresses in the the compat32 case (and also compat64 on
CheriBSD).
The motivating use-case for this change is using truss for 64-bit
programs on a CHERI system, but most of the diff also applies to 32-bit
compat on a 64-bit system, so I'm upstreaming this instead of keeping it
as a local CheriBSD patch.
Output of `truss -aef ldd32 /usr/bin/ldd32` before:
39113: freebsd32_mmap(0x0,0x1000,0x3,0x1002,0xffffffff,0x0,0x0) = 543440896 (0x20644000)
39113: freebsd32_ioctl(0x1,0x402c7413,0xffffd2a0) = 0 (0x0)
/usr/bin/ldd32:
39113: write(1,"/usr/bin/ldd32:\n",16) = 16 (0x10)
39113: fork() = 39114 (0x98ca)
39114: <new process>
39114: freebsd32_execve(0xffffd97e,0xffffd680,0x20634000) EJUSTRETURN
39114: freebsd32_mmap(0x0,0x20000,0x3,0x1002,0xffffffff,0x0,0x0) = 541237248 (0x2042a000)
39114: freebsd32_mprotect(0x20427000,0x1000,0x1) = 0 (0x0)
39114: issetugid() = 0 (0x0)
39114: openat(AT_FDCWD,"/etc/libmap32.conf",O_RDONLY|O_CLOEXEC,00) ERR#2 'No such file or directory'
39114: openat(AT_FDCWD,"/var/run/ld-elf32.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3)
39114: read(3,"Ehnt\^A\0\0\0\M^@\0\0\0#\0\0\0\0"...,128) = 128 (0x80)
39114: freebsd32_fstat(0x3,0xffffbd98) = 0 (0x0)
39114: freebsd32_pread(0x3,0x2042f000,0x23,0x80,0x0) = 35 (0x23)
39114: close(3) = 0 (0x0)
39114: openat(AT_FDCWD,"/usr/lib32/libc.so.7",O_RDONLY|O_CLOEXEC|O_VERIFY,00) = 3 (0x3)
39114: freebsd32_fstat(0x3,0xffffc7d0) = 0 (0x0)
39114: freebsd32_mmap(0x0,0x1000,0x1,0x40002,0x3,0x0,0x0) = 541368320 (0x2044a000)
After:
783: freebsd32_mmap(0x0,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON|MAP_ALIGNED(12),-1,0x0) = 543543296 (0x2065d000)
783: freebsd32_ioctl(1,TIOCGETA,0xffffd7b0) = 0 (0x0)
/usr/bin/ldd32:
783: write(1,"/usr/bin/ldd32:\n",16) = 16 (0x10)
784: <new process>
783: fork() = 784 (0x310)
784: freebsd32_execve("/usr/bin/ldd32",[ "(null)" ],[ "LD_32_TRACE_LOADED_OBJECTS_PROGNAME=/usr/bin/ldd32", "LD_TRACE_LOADED_OBJECTS_PROGNAME=/usr/bin/ldd32", "LD_32_TRACE_LOADED_OBJECTS=yes", "LD_TRACE_LOADED_OBJECTS=yes", "USER=root", "LOGNAME=root", "HOME=/root", "SHELL=/bin/csh", "BLOCKSIZE=K", "MAIL=/var/mail/root", "MM_CHARSET=UTF-8", "LANG=C.UTF-8", "PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/root/bin", "TERM=vt100", "HOSTTYPE=FreeBSD", "VENDOR=amd", "OSTYPE=FreeBSD", "MACHTYPE=x86_64", "SHLVL=1", "PWD=/root", "GROUP=wheel", "HOST=freebsd-amd64", "EDITOR=vi", "PAGER=less" ]) EJUSTRETURN
784: freebsd32_mmap(0x0,135168,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) = 541212672 (0x20424000)
784: freebsd32_mprotect(0x20421000,4096,PROT_READ) = 0 (0x0)
784: issetugid() = 0 (0x0)
784: sigfastblock(0x1,0x204234fc) = 0 (0x0)
784: open("/etc/libmap32.conf",O_RDONLY|O_CLOEXEC,00) ERR#2 'No such file or directory'
784: open("/var/run/ld-elf32.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3)
784: read(3,"Ehnt\^A\0\0\0\M^@\0\0\0\v\0\0\0"...,128) = 128 (0x80)
784: freebsd32_fstat(3,{ mode=-r--r--r-- ,inode=18680,size=32768,blksize=0 }) = 0 (0x0)
784: freebsd32_pread(3,"/usr/lib32\0",11,0x80) = 11 (0xb)
Reviewed By: jhb
Differential Revision: https://reviews.freebsd.org/D27625
This commit is contained in:
Alex Richardson
parent
29dd5e7a87
commit
7daca4e204
@ -74,59 +74,72 @@ static void new_proc(struct trussinfo *, pid_t, lwpid_t);
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static struct procabi cloudabi32 = {
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"CloudABI32",
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SYSDECODE_ABI_CLOUDABI32,
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STAILQ_HEAD_INITIALIZER(cloudabi32.extra_syscalls),
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{ NULL }
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.type = "CloudABI32",
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.abi = SYSDECODE_ABI_CLOUDABI32,
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.pointer_size = sizeof(uint32_t),
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(cloudabi32.extra_syscalls),
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.syscalls = { NULL }
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};
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static struct procabi cloudabi64 = {
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"CloudABI64",
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SYSDECODE_ABI_CLOUDABI64,
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STAILQ_HEAD_INITIALIZER(cloudabi64.extra_syscalls),
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{ NULL }
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.type = "CloudABI64",
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.abi = SYSDECODE_ABI_CLOUDABI64,
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.pointer_size = sizeof(uint64_t),
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(cloudabi64.extra_syscalls),
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.syscalls = { NULL }
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};
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static struct procabi freebsd = {
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"FreeBSD",
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SYSDECODE_ABI_FREEBSD,
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STAILQ_HEAD_INITIALIZER(freebsd.extra_syscalls),
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{ NULL }
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.type = "FreeBSD",
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.abi = SYSDECODE_ABI_FREEBSD,
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.pointer_size = sizeof(void *),
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(freebsd.extra_syscalls),
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.syscalls = { NULL }
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};
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#ifdef __LP64__
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#if !defined(__SIZEOF_POINTER__)
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#error "Use a modern compiler."
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#endif
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#if __SIZEOF_POINTER__ > 4
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static struct procabi freebsd32 = {
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"FreeBSD32",
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SYSDECODE_ABI_FREEBSD32,
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STAILQ_HEAD_INITIALIZER(freebsd32.extra_syscalls),
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{ NULL }
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.type = "FreeBSD32",
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.abi = SYSDECODE_ABI_FREEBSD32,
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.pointer_size = sizeof(uint32_t),
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.compat_prefix = "freebsd32",
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(freebsd32.extra_syscalls),
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.syscalls = { NULL }
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};
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#endif
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static struct procabi linux = {
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"Linux",
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SYSDECODE_ABI_LINUX,
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STAILQ_HEAD_INITIALIZER(linux.extra_syscalls),
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{ NULL }
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.type = "Linux",
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.abi = SYSDECODE_ABI_LINUX,
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.pointer_size = sizeof(void *),
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(linux.extra_syscalls),
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.syscalls = { NULL }
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};
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#ifdef __LP64__
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#if __SIZEOF_POINTER__ > 4
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static struct procabi linux32 = {
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"Linux32",
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SYSDECODE_ABI_LINUX32,
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STAILQ_HEAD_INITIALIZER(linux32.extra_syscalls),
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{ NULL }
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.type = "Linux32",
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.abi = SYSDECODE_ABI_LINUX32,
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.pointer_size = sizeof(uint32_t),
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.extra_syscalls = STAILQ_HEAD_INITIALIZER(linux32.extra_syscalls),
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.syscalls = { NULL }
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};
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#endif
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static struct procabi_table abis[] = {
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{ "CloudABI ELF32", &cloudabi32 },
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{ "CloudABI ELF64", &cloudabi64 },
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#ifdef __LP64__
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#if __SIZEOF_POINTER__ == 4
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{ "FreeBSD ELF32", &freebsd },
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#elif __SIZEOF_POINTER__ == 8
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{ "FreeBSD ELF64", &freebsd },
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{ "FreeBSD ELF32", &freebsd32 },
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#else
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{ "FreeBSD ELF32", &freebsd },
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#error "Unsupported pointer size"
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#endif
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#if defined(__powerpc64__)
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{ "FreeBSD ELF64 V2", &freebsd },
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@ -137,7 +150,7 @@ static struct procabi_table abis[] = {
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#if defined(__i386__)
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{ "FreeBSD a.out", &freebsd },
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#endif
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#ifdef __LP64__
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#if __SIZEOF_POINTER__ >= 8
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{ "Linux ELF64", &linux },
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{ "Linux ELF32", &linux32 },
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#else
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@ -963,7 +963,6 @@ print_mask_arg32(bool (*decoder)(FILE *, uint32_t, uint32_t *), FILE *fp,
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fprintf(fp, "|0x%x", rem);
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}
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#ifndef __LP64__
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/*
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* Add argument padding to subsequent system calls after Quad
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* syscall arguments as needed. This used to be done by hand in the
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@ -1008,7 +1007,6 @@ quad_fixup(struct syscall_decode *sc)
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}
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}
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}
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#endif
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static struct syscall *
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find_syscall(struct procabi *abi, u_int number)
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@ -1029,10 +1027,13 @@ add_syscall(struct procabi *abi, u_int number, struct syscall *sc)
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{
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struct extra_syscall *es;
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#ifndef __LP64__
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/* FIXME: should be based on syscall ABI not truss ABI */
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/*
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* quad_fixup() is currently needed for all 32-bit ABIs.
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* TODO: This should probably be a function pointer inside struct
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* procabi instead.
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*/
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if (abi->pointer_size == 4)
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quad_fixup(&sc->decode);
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#endif
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if (number < nitems(abi->syscalls)) {
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assert(abi->syscalls[number] == NULL);
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@ -1055,16 +1056,19 @@ struct syscall *
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get_syscall(struct threadinfo *t, u_int number, u_int nargs)
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{
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struct syscall *sc;
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struct procabi *procabi;
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const char *sysdecode_name;
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const char *lookup_name;
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const char *name;
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u_int i;
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sc = find_syscall(t->proc->abi, number);
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procabi = t->proc->abi;
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sc = find_syscall(procabi, number);
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if (sc != NULL)
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return (sc);
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/* Memory is not explicitly deallocated, it's released on exit(). */
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sysdecode_name = sysdecode_syscallname(t->proc->abi->abi, number);
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sysdecode_name = sysdecode_syscallname(procabi->abi, number);
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if (sysdecode_name == NULL)
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asprintf(__DECONST(char **, &name), "#%d", number);
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else
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@ -1073,8 +1077,14 @@ get_syscall(struct threadinfo *t, u_int number, u_int nargs)
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sc = calloc(1, sizeof(*sc));
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sc->name = name;
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/* Also decode compat syscalls arguments by stripping the prefix. */
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lookup_name = name;
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if (procabi->compat_prefix != NULL && strncmp(procabi->compat_prefix,
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name, strlen(procabi->compat_prefix)) == 0)
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lookup_name += strlen(procabi->compat_prefix);
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for (i = 0; i < nitems(decoded_syscalls); i++) {
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if (strcmp(name, decoded_syscalls[i].name) == 0) {
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if (strcmp(lookup_name, decoded_syscalls[i].name) == 0) {
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sc->decode = decoded_syscalls[i];
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add_syscall(t->proc->abi, number, sc);
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return (sc);
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@ -1817,12 +1827,15 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval,
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case StringArray: {
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uintptr_t addr;
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union {
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char *strarray[0];
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int32_t strarray32[PAGE_SIZE / sizeof(int32_t)];
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int64_t strarray64[PAGE_SIZE / sizeof(int64_t)];
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char buf[PAGE_SIZE];
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} u;
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char *string;
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size_t len;
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u_int first, i;
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size_t pointer_size =
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trussinfo->curthread->proc->abi->pointer_size;
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/*
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* Only parse argv[] and environment arrays from exec calls
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@ -1842,7 +1855,7 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval,
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* a partial page.
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*/
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addr = args[sc->offset];
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if (addr % sizeof(char *) != 0) {
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if (addr % pointer_size != 0) {
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print_pointer(fp, args[sc->offset]);
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break;
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}
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@ -1852,22 +1865,36 @@ print_arg(struct syscall_arg *sc, unsigned long *args, register_t *retval,
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print_pointer(fp, args[sc->offset]);
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break;
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}
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assert(len > 0);
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fputc('[', fp);
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first = 1;
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i = 0;
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while (u.strarray[i] != NULL) {
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string = get_string(pid, (uintptr_t)u.strarray[i], 0);
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for (;;) {
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uintptr_t straddr;
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if (pointer_size == 4) {
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if (u.strarray32[i] == 0)
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break;
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/* sign-extend 32-bit pointers */
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straddr = (intptr_t)u.strarray32[i];
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} else if (pointer_size == 8) {
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if (u.strarray64[i] == 0)
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break;
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straddr = (intptr_t)u.strarray64[i];
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} else {
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errx(1, "Unsupported pointer size: %zu",
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pointer_size);
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}
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string = get_string(pid, straddr, 0);
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fprintf(fp, "%s \"%s\"", first ? "" : ",", string);
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free(string);
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first = 0;
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i++;
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if (i == len / sizeof(char *)) {
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if (i == len / pointer_size) {
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addr += len;
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len = PAGE_SIZE;
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if (get_struct(pid, addr, u.buf, len) ==
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-1) {
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if (get_struct(pid, addr, u.buf, len) == -1) {
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fprintf(fp, ", <inval>");
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break;
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}
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@ -58,6 +58,8 @@ struct extra_syscall {
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struct procabi {
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const char *type;
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enum sysdecode_abi abi;
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size_t pointer_size;
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const char *compat_prefix;
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STAILQ_HEAD(, extra_syscall) extra_syscalls;
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struct syscall *syscalls[SYSCALL_NORMAL_COUNT];
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};
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