Commit f4d92c5e authored by Filip Bozuta's avatar Filip Bozuta Committed by Laurent Vivier
Browse files

linux-user: Add strace support for printing arguments of fallocate() 

This patch implements strace argument printing functionality for following syscall:

    *fallocate - manipulate file space

        int fallocate(int fd, int mode, off_t offset, off_t len)
        man page: https://www.man7.org/linux/man-pages/man2/fallocate.2.html



Implementation notes:

    This syscall's second argument "mode" is composed of predefined values
    which represent flags that determine the type of operation that is
    to be performed on the file space. For that reason, a printing
    function "print_fallocate" was stated in file "strace.list". This printing
    function uses an already existing function "print_flags()" to print flags of
    the "mode" argument. These flags are stated inside an array "falloc_flags"
    that contains values of type "struct flags". These values are instantiated
    using an existing macro "FLAG_GENERIC()". Most of these flags are defined
    after kernel version 3.0 which is why they are enwrapped in an #ifdef
    directive.
    The syscall's third ant fourth argument are of type "off_t" which can
    cause variations between 32/64-bit architectures. To handle this variation,
    function "target_offset64()" was copied from file "strace.c" and used in
    "print_fallocate" to print "off_t" arguments for 32-bit architectures.

Signed-off-by: default avatarFilip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: default avatarLaurent Vivier <laurent@vivier.eu>
Message-Id: <20200619123331.17387-7-filip.bozuta@syrmia.com>
Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
parent 5844f4bc

linux-user/qemu.h

+16 −0
Original line number Diff line number Diff line
@@ -670,6 +670,22 @@ static inline int is_error(abi_long ret) 
    return (abi_ulong)ret >= (abi_ulong)(-4096);

}



#if TARGET_ABI_BITS == 32

static inline uint64_t target_offset64(uint32_t word0, uint32_t word1)

{

#ifdef TARGET_WORDS_BIGENDIAN

    return ((uint64_t)word0 << 32) | word1;

#else

    return ((uint64_t)word1 << 32) | word0;

#endif

}

#else /* TARGET_ABI_BITS == 32 */

static inline uint64_t target_offset64(uint64_t word0, uint64_t word1)

{

    return word0;

}

#endif /* TARGET_ABI_BITS != 32 */



/**

 * preexit_cleanup: housekeeping before the guest exits

 *

linux-user/strace.c

+40 −0
Original line number Diff line number Diff line
@@ -1135,6 +1135,26 @@ UNUSED static struct flags statx_mask[] = { 
    FLAG_END,

};



UNUSED static struct flags falloc_flags[] = {

    FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),

    FLAG_GENERIC(FALLOC_FL_PUNCH_HOLE),

#ifdef FALLOC_FL_NO_HIDE_STALE

    FLAG_GENERIC(FALLOC_FL_NO_HIDE_STALE),

#endif

#ifdef FALLOC_FL_COLLAPSE_RANGE

    FLAG_GENERIC(FALLOC_FL_COLLAPSE_RANGE),

#endif

#ifdef FALLOC_FL_ZERO_RANGE

    FLAG_GENERIC(FALLOC_FL_ZERO_RANGE),

#endif

#ifdef FALLOC_FL_INSERT_RANGE

    FLAG_GENERIC(FALLOC_FL_INSERT_RANGE),

#endif

#ifdef FALLOC_FL_UNSHARE_RANGE

    FLAG_GENERIC(FALLOC_FL_UNSHARE_RANGE),

#endif

};



/*

 * print_xxx utility functions.  These are used to print syscall

 * parameters in certain format.  All of these have parameter
@@ -1552,6 +1572,26 @@ print_faccessat(const struct syscallname *name, 
}

#endif



#ifdef TARGET_NR_fallocate

static void

print_fallocate(const struct syscallname *name,

    abi_long arg0, abi_long arg1, abi_long arg2,

    abi_long arg3, abi_long arg4, abi_long arg5)

{

    print_syscall_prologue(name);

    print_raw_param("%d", arg0, 0);

    print_flags(falloc_flags, arg1, 0);

#if TARGET_ABI_BITS == 32

    print_raw_param("%" PRIu64, target_offset64(arg2, arg3), 0);

    print_raw_param("%" PRIu64, target_offset64(arg4, arg5), 1);

#else

    print_raw_param(TARGET_ABI_FMT_ld, arg2, 0);

    print_raw_param(TARGET_ABI_FMT_ld, arg3, 1);

#endif

    print_syscall_epilogue(name);

}

#endif



#ifdef TARGET_NR_fchmodat

static void

print_fchmodat(const struct syscallname *name,

linux-user/strace.list

+1 −1
Original line number Diff line number Diff line
@@ -182,7 +182,7 @@ 
{ TARGET_NR_fadvise64_64, "fadvise64_64" , NULL, NULL, NULL },

#endif

#ifdef TARGET_NR_fallocate

{ TARGET_NR_fallocate, "fallocate" , NULL, NULL, NULL },

{ TARGET_NR_fallocate, "fallocate" , NULL, print_fallocate, NULL },

#endif

#ifdef TARGET_NR_fanotify_init

{ TARGET_NR_fanotify_init, "fanotify_init" , NULL, NULL, NULL },

linux-user/syscall.c

+0 −16
Original line number Diff line number Diff line
@@ -6712,22 +6712,6 @@ void syscall_init(void) 
    }

}



#if TARGET_ABI_BITS == 32

static inline uint64_t target_offset64(uint32_t word0, uint32_t word1)

{

#ifdef TARGET_WORDS_BIGENDIAN

    return ((uint64_t)word0 << 32) | word1;

#else

    return ((uint64_t)word1 << 32) | word0;

#endif

}

#else /* TARGET_ABI_BITS == 32 */

static inline uint64_t target_offset64(uint64_t word0, uint64_t word1)

{

    return word0;

}

#endif /* TARGET_ABI_BITS != 32 */



#ifdef TARGET_NR_truncate64

static inline abi_long target_truncate64(void *cpu_env, const char *arg1,

                                         abi_long arg2,