Linux-5.10 has introduced SEV-ES support. New (5th) exception
stack was added: 'VC_stack'.

'struct exception_stacks' cannot be used to obtain size of
VC stack, as it equals zero there. Try another structure
'struct cea_exception_stacks' first as it represents actual
CPU entry area with valid stack sizes and guard pages.

Added check for zero size stack to avoid stack parsing
issues.

Signed-off-by: Alexey Makhalov <amakha...@vmware.com>
---
 x86_64.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/x86_64.c b/x86_64.c
index fc05e8a..ea4a894 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -1367,6 +1367,7 @@ x86_64_ist_init(void)
        ulong init_tss;
        struct machine_specific *ms;
        struct syment *boot_sp, *tss_sp, *ist_sp;
+       char *exc_stack_struct_name = NULL;
 
         ms = machdep->machspec;
        if (!(tss_sp = per_cpu_symbol_search("per_cpu__init_tss"))) {
@@ -1442,16 +1443,25 @@ x86_64_ist_init(void)
                return;
        }
 
-       if (MEMBER_EXISTS("exception_stacks", "NMI_stack")) {
+       if (MEMBER_EXISTS("cea_exception_stacks", "NMI_stack")) {
+               /* The effective cpu entry area mapping with guard pages. */
+               exc_stack_struct_name = "cea_exception_stacks";
+       } else if (MEMBER_EXISTS("exception_stacks", "NMI_stack")) {
+               /* The exception stacks' physical storage. No guard pages and 
no VC stack. */
+               exc_stack_struct_name = "exception_stacks";
+       }
+       if (exc_stack_struct_name) {
                 for (i = 0; i < MAX_EXCEPTION_STACKS; i++) {
                        if (STREQ(ms->stkinfo.exception_stacks[i], "DEBUG"))
-                               ms->stkinfo.esize[i] = 
MEMBER_SIZE("exception_stacks", "DB_stack");
+                               ms->stkinfo.esize[i] = 
MEMBER_SIZE(exc_stack_struct_name, "DB_stack");
                        else if (STREQ(ms->stkinfo.exception_stacks[i], "NMI"))
-                               ms->stkinfo.esize[i] = 
MEMBER_SIZE("exception_stacks", "NMI_stack");
+                               ms->stkinfo.esize[i] = 
MEMBER_SIZE(exc_stack_struct_name, "NMI_stack");
                        else if (STREQ(ms->stkinfo.exception_stacks[i], 
"DOUBLEFAULT"))
-                               ms->stkinfo.esize[i] = 
MEMBER_SIZE("exception_stacks", "DF_stack");
+                               ms->stkinfo.esize[i] = 
MEMBER_SIZE(exc_stack_struct_name, "DF_stack");
                        else if (STREQ(ms->stkinfo.exception_stacks[i], "MCE"))
-                               ms->stkinfo.esize[i] = 
MEMBER_SIZE("exception_stacks", "MCE_stack");
+                               ms->stkinfo.esize[i] = 
MEMBER_SIZE(exc_stack_struct_name, "MCE_stack");
+                       else if (STREQ(ms->stkinfo.exception_stacks[i], "VC"))
+                               ms->stkinfo.esize[i] = 
MEMBER_SIZE(exc_stack_struct_name, "VC_stack");
                }
                /*
                 *  Adjust the top-of-stack addresses down to the base stack 
address.
@@ -5090,7 +5100,7 @@ skip_stage:
                        ms->stkinfo.esize[estack];
                console("x86_64_get_dumpfile_stack_frame: searching %s estack 
at %lx\n", 
                        ms->stkinfo.exception_stacks[estack], bt->stackbase);
-               if (!(bt->stackbase)) 
+               if (!(bt->stackbase) || !(ms->stkinfo.esize[estack]))
                        goto skip_stage;
                bt->stackbuf = ms->irqstack;
                alter_stackbuf(bt);
@@ -5373,6 +5383,8 @@ x86_64_exception_stacks_init(void)
                                ms->stkinfo.exception_stacks[ist-1] = 
"DOUBLEFAULT";
                        if (strstr(buf, "machine"))
                                ms->stkinfo.exception_stacks[ist-1] = "MCE";
+                       if (strstr(buf, "vmm"))
+                               ms->stkinfo.exception_stacks[ist-1] = "VC";
                }
        }
 
-- 
2.11.0

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