[PATCH v5 03/17] xenctx: Add -n (--display-stack-pages) option to output larger stack

[Don Slutz <dslutz@verizon.com>]

From: Don Slutz <Don@CloudSwitch.com>

Important: This is the stack size to display not the configured
stack size.

Note: use with caution (easy to get garbage).

Below is various pictures of a configured 3 page stack, and where
the SP currently is.  Each box is a page.

       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+
       |                  |
       |                  |
       |                  |
SP --> |                  |
       |                  |
       +------------------+

Display using "-n 1" since the used stack pages is 1.

       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+
       |                  |
SP --> |                  |
       |                  |
       |                  |
       |                  |
       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+

Display using "-n 2" since the used stack pages is 2.

       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
SP --> |                  |
       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+
       |                  |
       |                  |
       |                  |
       |                  |
       |                  |
       +------------------+

Display using "-n 3" since the used stack pages is 3.

Signed-off-by: Don Slutz <Don@CloudSwitch.com>
---
v5: Adjust option to -n, --display-stack-pages.  Adjust usage message.

 tools/xentrace/xenctx.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/xentrace/xenctx.c b/tools/xentrace/xenctx.c
index 42a47f3..caa8899 100644
--- a/tools/xentrace/xenctx.c
+++ b/tools/xentrace/xenctx.c
@@ -35,6 +35,7 @@ static struct xenctx {
     int frame_ptrs;
     int stack_trace;
     int disp_all;
+    int multiple_pages;
     int all_vcpus;
     int self_paused;
     xc_dominfo_t dominfo;
@@ -664,6 +665,8 @@ static int print_stack(vcpu_guest_context_any_t *ctx, int vcpu, int width)
 
     stack_limit = ((stack_pointer(ctx) + XC_PAGE_SIZE)
                    & ~((guest_word_t) XC_PAGE_SIZE - 1));
+    if ( xenctx.multiple_pages > 1 )
+        stack_limit += (xenctx.multiple_pages - 1) * XC_PAGE_SIZE;
     printf("\n");
     printf("Stack:\n");
     for (i=1; i<5 && stack < stack_limit; i++) {
@@ -834,18 +837,22 @@ static void usage(void)
         kernel_start);
     printf("  -a, --all          display more registers\n");
     printf("  -C, --all-vcpus    print info for all vcpus\n");
+    printf("  -n PAGES, --display-stack-pages=PAGES\n");
+    printf("                     Display N pages from the stack pointer.\n");
+    printf("                     Note: use with caution (easy to get garbage).\n");
 }
 
 int main(int argc, char **argv)
 {
     int ch;
     int ret;
-    static const char *sopts = "fs:hak:SC";
+    static const char *sopts = "fs:hak:SCn:";
     static const struct option lopts[] = {
         {"stack-trace", 0, NULL, 'S'},
         {"symbol-table", 1, NULL, 's'},
         {"frame-pointers", 0, NULL, 'f'},
         {"kernel-start", 1, NULL, 'k'},
+        {"display-stack-pages", 0, NULL, 'n'},
         {"all", 0, NULL, 'a'},
         {"all-vcpus", 0, NULL, 'C'},
         {"help", 0, NULL, 'h'},
@@ -869,6 +876,9 @@ int main(int argc, char **argv)
         case 'a':
             xenctx.disp_all = 1;
             break;
+        case 'n':
+            xenctx.multiple_pages = strtol(optarg, NULL, 0);
+            break;
         case 'C':
             xenctx.all_vcpus = 1;
             break;
-- 
1.8.4