On Mon, Jun 24, 2013 at 12:18:58AM -0700, Luca Clementi wrote:
> This patch prints the stack trace of the traced process after
> each system call when using -k flag. It uses libunwind to
> unwind the stack and to obtain the function name pointed by
> the IP.
[...]
> --- a/defs.h
> +++ b/defs.h
> @@ -392,6 +392,29 @@ typedef struct ioctlent {
> unsigned long code;
> } struct_ioctlent;
>
> +
> +#ifdef LIB_UNWIND
> +#include <libunwind-ptrace.h>
> +#include <libunwind.h>
Please avoid including feature-specific header files in defs.h because the
latter is included by all translation units. Just include these headers
where they are really needed.
> +/* keep a sorted array of cache entries, so that we can binary search
> + * through it
> + */
> +struct mmap_cache_t {
> + // example entry:
> + // 7fabbb09b000-7fabbb09f000 r--p 00179000 fc:00 1180246
> /lib/libc-2.11.1.so
> + //
> + // start_addr is 0x7fabbb09b000
> + // end_addr is 0x7fabbb09f000
> + // mmap_offset is 0x179000
> + // binary_filename is "/lib/libc-2.11.1.so"
> + unsigned long start_addr;
> + unsigned long end_addr;
> + unsigned long mmap_offset;
> + char* binary_filename;
> +};
> +#endif
> +
> /* Trace Control Block */
> struct tcb {
> int flags; /* See below for TCB_ values */
> @@ -417,6 +440,13 @@ struct tcb {
> struct timeval etime; /* Syscall entry time */
> /* Support for tracing forked processes: */
> long inst[2]; /* Saved clone args (badly named) */
> +
> +#ifdef LIB_UNWIND
> + // keep a cache of /proc/<pid>/mmap contents to avoid unnecessary file
> reads
> + struct mmap_cache_t* mmap_cache;
> + int mmap_cache_size;
> + struct UPT_info* libunwind_ui;
> +#endif
> };
This can stay in defs.h without including libunwind header files,
just add a forward declaration for struct UPT_info.
> /* TCB flags */
> @@ -710,6 +740,14 @@ extern void tv_sub(struct timeval *, struct timeval *,
> struct timeval *);
> extern void tv_mul(struct timeval *, struct timeval *, int);
> extern void tv_div(struct timeval *, struct timeval *, int);
>
> +#ifdef LIB_UNWIND
> +/**
> + * print stack (-k flag) memory allocation and deallocation
> + */
> +extern void alloc_mmap_cache(struct tcb* tcp);
> +extern void delete_mmap_cache(struct tcb* tcp);
> +#endif
Please add here all declarations you need, avoid placing them in *.c files.
> +#ifdef LIB_UNWIND
> + if (!entering(tcp))
> + delete_mmap_cache(tcp);
> +#endif
In all such places, please use "exiting" instead of "!entering".
> + if (use_libunwind) {
> + tcp->libunwind_ui = _UPT_create(tcp->pid);
> + }
If _UPT_create allocates memory, it can fail.
Please check return code of all functions that allocate memory.
> --- a/syscall.c
> +++ b/syscall.c
> @@ -1946,6 +1946,194 @@ get_syscall_args(struct tcb *tcp)
> return 1;
> }
>
> +#ifdef LIB_UNWIND
> +
> +extern unw_addr_space_t libunwind_as;
> +
> +/*
> + * caching of /proc/ID/maps for each process to speed up stack tracing
> + *
> + * The cache must be refreshed after some syscall: mmap, mprotect, munmap,
> execve
> + */
> +void alloc_mmap_cache(struct tcb* tcp) {
The code you are working on is quite specific, so please create a new
translation unit (e.g. unwind.c) and place all new definitions there.
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