Re: [Qemu-devel] [PATCH] Fix for RSP vCont packet

[Eric Blake]

On 1/30/19 6:41 PM, Lucien Anti-Spam via Qemu-devel wrote:
> This fixes a regression in rsp packet vCont due to recently added 
> multiprocess support. (Short commit hash: e40e520).
> 

Your mailer completely botched the message (wrong line endings?)  Can
you please resend, preferably using git send-email, or at a minimum
attaching git format-patch output rather than inline pasting, so that we
stand a chance of seeing what you actually intended?

> The result is that vCont now does not recognise the case where no 
> process/thread is provided after the action.
> This may not show up with GDB, but using Lauterbach Trace32, and Hexrays IDA 
> Pro this issue is immediately seen.The response is a "$#00" empty packet, 
> showing it is unsupported packet.
> This is defined in the RSP document as "An action with no thread-id matches 
> all 
> threads."(https://sourceware.org/gdb/current/onlinedocs/gdb/Packets.html#vCont-packet
>  )
> Thus the valid vCont packets now are as below, however parsing is still not 
> very strict.  vCont;c/s                 - Step/Continue all threads  
> vCont;c/s:[pX.]Y          - Step/Continue optional process X, thread Y  
> vCont;C##/S##:[pX.]Y      - Step/Continue with signal ## on optional process 
> X, thread Y  * If X or Y are -1 then it applies the action to all 
> processes/threads.
> Signed-off-by: Lucien Murray-Pitts <address@hidden>--- gdbstub.c | 16 
> ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
> diff --git a/gdbstub.c b/gdbstub.cindex bfc7afb509..ce0dde2e24 100644--- 
> a/gdbstub.c+++ b/gdbstub.c@@ -1169,6 +1169,7 @@ static int 
> is_query_packet(const char *p, const char *query, char separator)  */ static 
> int gdb_handle_vcont(GDBState *s, const char *p) {+    GDBThreadIdKind 
> vcontThreadType ;     int res, signal = 0;     char cur_action;     char 
> *newstates;@@ -1218,12 +1219,23 @@ static int gdb_handle_vcont(GDBState *s, 
> const char *p)             goto out;         } -        if (*p++ != ':') {+   
>      /*+         * In the case we have vCont;c or vCont;s - action is on all 
> threads+         * Alternatively vCont;c;s:p1.1 is a possible, but 
> meaningless format,+         * And in the else the "vCont;c:p1.1;... format 
> is supported.+         */+        if (*p == '\0' || *p == ';') {+            
> vcontThreadType = GDB_ALL_THREADS ;+            pid = 1 ;+            tid = 1 
> ;+        } else if (*p++ == ':') {+            vcontThreadType = 
> read_thread_id(p, &p, &pid, &tid) ;+        } else {             res = 
> -ENOTSUP;             goto out;         } -        switch (read_thread_id(p, 
> &p, &pid, &tid)) {+        switch (vcontThreadType) {         case 
> GDB_READ_THREAD_ERR:             res = -EINVAL;             goto out;-- 2.17.2
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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