From c84be71f685436fd7216a159528421c3d7af8d05 Mon Sep 17 00:00:00 2001 From: Filip Bozuta Date: Fri, 19 Jun 2020 14:33:26 +0200 Subject: [PATCH] linux-user: Extend strace support to enable argument printing after syscall execution Structure "struct syscallname" in file "strace.c" is used for "-strace" to print arguments and return values of syscalls. The last field of this structure "result" represents the calling function that prints the return values. This field was extended in this patch so that this function takes all syscalls arguments beside the return value. In this way, it enables "-strace" to print arguments of syscalls that have changed after the syscall execution. This extension will be useful as there are many syscalls that return values inside their arguments (i.e. listxattr() that returns the list of extended attributes inside the "list" argument). Implementation notes: Since there are already three existing "print_syscall_ret*" functions inside "strace.c" ("print_syscall_ret_addr()", "print_syscall_ret_adjtimex()", "print_syscall_ret_newselect()"), they were changed to have all syscall arguments beside the return value. This was done so that these functions don't cause build errors (even though syscall arguments are not used in these functions). There is code repetition in these functions for checking the return value and printing the approppriate error message (this code is also located in print_syscall_ret() at the end of "strace.c"). That is the reason why a function "syscall_print_err()" was added for this code and put inside these functions. Functions "print_newselect()" and "print_syscall_ret_newselect()" were changed to use this new implemented functionality and not store the syscall argument values in separate static variables. Signed-off-by: Filip Bozuta Reviewed-by: Laurent Vivier Message-Id: <20200619123331.17387-2-filip.bozuta@syrmia.com> Signed-off-by: Laurent Vivier --- linux-user/qemu.h | 4 +- linux-user/strace.c | 108 ++++++++++++++++++++++--------------------- linux-user/syscall.c | 2 +- 3 files changed, 60 insertions(+), 54 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index ce902f5132..8f938b8105 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -383,7 +383,9 @@ int host_to_target_waitstatus(int status); void print_syscall(int num, abi_long arg1, abi_long arg2, abi_long arg3, abi_long arg4, abi_long arg5, abi_long arg6); -void print_syscall_ret(int num, abi_long arg1); +void print_syscall_ret(int num, abi_long ret, + abi_long arg1, abi_long arg2, abi_long arg3, + abi_long arg4, abi_long arg5, abi_long arg6); /** * print_taken_signal: * @target_signum: target signal being taken diff --git a/linux-user/strace.c b/linux-user/strace.c index 0d9095c674..62117e8555 100644 --- a/linux-user/strace.c +++ b/linux-user/strace.c @@ -19,7 +19,9 @@ struct syscallname { void (*call)(const struct syscallname *, abi_long, abi_long, abi_long, abi_long, abi_long, abi_long); - void (*result)(const struct syscallname *, abi_long); + void (*result)(const struct syscallname *, abi_long, + abi_long, abi_long, abi_long, + abi_long, abi_long, abi_long); }; #ifdef __GNUC__ @@ -631,18 +633,12 @@ print_clockid(int clockid, int last) /* select */ #ifdef TARGET_NR__newselect -static long newselect_arg1 = 0; -static long newselect_arg2 = 0; -static long newselect_arg3 = 0; -static long newselect_arg4 = 0; -static long newselect_arg5 = 0; - static void print_newselect(const struct syscallname *name, abi_long arg1, abi_long arg2, abi_long arg3, abi_long arg4, abi_long arg5, abi_long arg6) { - qemu_log("%s(" TARGET_ABI_FMT_ld ",", name->name, arg1); + print_syscall_prologue(name); print_fdset(arg1, arg2); qemu_log(","); print_fdset(arg1, arg3); @@ -650,14 +646,7 @@ print_newselect(const struct syscallname *name, print_fdset(arg1, arg4); qemu_log(","); print_timeval(arg5, 1); - qemu_log(")"); - - /* save for use in the return output function below */ - newselect_arg1=arg1; - newselect_arg2=arg2; - newselect_arg3=arg3; - newselect_arg4=arg4; - newselect_arg5=arg5; + print_syscall_epilogue(name); } #endif @@ -736,17 +725,29 @@ print_ipc(const struct syscallname *name, */ static void -print_syscall_ret_addr(const struct syscallname *name, abi_long ret) +print_syscall_err(abi_long ret) { const char *errstr = NULL; + qemu_log(" = "); if (ret < 0) { + qemu_log("-1 errno=%d", errno); errstr = target_strerror(-ret); + if (errstr) { + qemu_log(" (%s)", errstr); + } } - if (errstr) { - qemu_log(" = -1 errno=%d (%s)\n", (int)-ret, errstr); - } else { - qemu_log(" = 0x" TARGET_ABI_FMT_lx "\n", ret); +} + +static void +print_syscall_ret_addr(const struct syscallname *name, abi_long ret, + abi_long arg0, abi_long arg1, abi_long arg2, + abi_long arg3, abi_long arg4, abi_long arg5) +{ + print_syscall_err(ret); + + if (ret >= 0) { + qemu_log("0x" TARGET_ABI_FMT_lx "\n", ret); } } @@ -760,17 +761,25 @@ print_syscall_ret_raw(struct syscallname *name, abi_long ret) #ifdef TARGET_NR__newselect static void -print_syscall_ret_newselect(const struct syscallname *name, abi_long ret) +print_syscall_ret_newselect(const struct syscallname *name, abi_long ret, + abi_long arg0, abi_long arg1, abi_long arg2, + abi_long arg3, abi_long arg4, abi_long arg5) { - qemu_log(" = 0x" TARGET_ABI_FMT_lx " (", ret); - print_fdset(newselect_arg1,newselect_arg2); - qemu_log(","); - print_fdset(newselect_arg1,newselect_arg3); - qemu_log(","); - print_fdset(newselect_arg1,newselect_arg4); - qemu_log(","); - print_timeval(newselect_arg5, 1); - qemu_log(")\n"); + print_syscall_err(ret); + + if (ret >= 0) { + qemu_log(" = 0x" TARGET_ABI_FMT_lx " (", ret); + print_fdset(arg0, arg1); + qemu_log(","); + print_fdset(arg0, arg2); + qemu_log(","); + print_fdset(arg0, arg3); + qemu_log(","); + print_timeval(arg4, 1); + qemu_log(")"); + } + + qemu_log("\n"); } #endif @@ -783,18 +792,13 @@ print_syscall_ret_newselect(const struct syscallname *name, abi_long ret) #define TARGET_TIME_ERROR 5 /* clock not synchronized */ #ifdef TARGET_NR_adjtimex static void -print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret) +print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret, + abi_long arg0, abi_long arg1, abi_long arg2, + abi_long arg3, abi_long arg4, abi_long arg5) { - const char *errstr = NULL; + print_syscall_err(ret); - qemu_log(" = "); - if (ret < 0) { - qemu_log("-1 errno=%d", errno); - errstr = target_strerror(-ret); - if (errstr) { - qemu_log(" (%s)", errstr); - } - } else { + if (ret >= 0) { qemu_log(TARGET_ABI_FMT_ld, ret); switch (ret) { case TARGET_TIME_OK: @@ -2847,25 +2851,25 @@ print_syscall(int num, void -print_syscall_ret(int num, abi_long ret) +print_syscall_ret(int num, abi_long ret, + abi_long arg1, abi_long arg2, abi_long arg3, + abi_long arg4, abi_long arg5, abi_long arg6) { int i; - const char *errstr = NULL; for(i=0;i= 0) { + qemu_log(TARGET_ABI_FMT_ld, ret); } + qemu_log("\n"); } break; } diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 17ed7f8d6b..1b971c06b2 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -12565,7 +12565,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, arg5, arg6, arg7, arg8); if (unlikely(qemu_loglevel_mask(LOG_STRACE))) { - print_syscall_ret(num, ret); + print_syscall_ret(num, ret, arg1, arg2, arg3, arg4, arg5, arg6); } record_syscall_return(cpu, num, ret);