[Crash-utility] Re: [PATCH] x86_64: Mark #VC stack unavailable when CONFIG_AMD_MEM_ENCRYPT is not set

On Fri, Dec 13, 2024 at 02:48:13PM +0800, lijiang wrote: > On Wed, Dec 11, 2024 at 10:22 AM <devel-request(a)lists.crash-utility.osci.io&gt; > wrote: > > > Date: Tue, 10 Dec 2024 20:18:43 +0800 > > From: "Hou Wenlong" <houwenlong.hwl(a)antgroup.com&gt; > > Subject: [Crash-utility] [PATCH] x86_64: Mark #VC stack unavailable > > when CONFIG_AMD_MEM_ENCRYPT is not set > > To: devel(a)lists.crash-utility.osci.io > > Cc: Hou Wenlong <houwenlong.hwl(a)antgroup.com&gt; > > Message-ID: <f1fca9918841de9a48f428d498f50964f1dab543.1733831073.git.h > > ouwenlong.hwl(a)antgroup.com&gt; > > > > When 'CONFIG_AMD_MEM_ENCRYPT' is not set, the IDT handler for #VC is not > > registered, but the address of the #VC IST stack is still set in > > tss_setup_ist(). Therefore, the name of the associated exception stack > > is "UNKNOWN" instead of "VC". Although the base of the exception stack > > is not zero and is available, it is not accessible, which will cause the > > backtrace to fail when attempting to access the #VC stack. To fix this, > > remove the name check. > > > > > Thank you for the fix, Hou. > > > > Signe-off-by: Hou Wenlong <houwenlong.hwl(a)antgroup.com&gt; > > --- > > x86_64.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/x86_64.c b/x86_64.c > > index e7f8fe25b31f..ee12ba095e6e 100644 > > --- a/x86_64.c > > +++ b/x86_64.c > > @@ -1540,7 +1540,7 @@ x86_64_ist_init(void) > > > > ms->stkinfo.available[c][i] = TRUE; > > /* VC stack can be unmapped if SEV-ES is > > disabled or not supported. */ > > - if (STREQ(ms->stkinfo.exception_stacks[i], > > "VC") && > > + if (ms->stkinfo.ebase[c][i] && > > > Can you help double check if the above condition is redundant in your case? > Seems the check '!accessible(ms->stkinfo.ebase[c][i])' should be enough. > Hi Lianbo, Yes, checking '!accessible(ms->stkinfo.ebase[c][i])' is sufficient. I added the extra check because I noticed that a value of 0 seems to be invalid for 'ms->stkinfo.ebase[c][i]', and there is a separate check for 'ms->stkinfo.ebase[c][i] != 0' before it is used in other places. If we remove the check, it could potentially be rewritten as: diff --git a/x86_64.c b/x86_64.c index e7f8fe25b31f..c254c6ec7576 100644 --- a/x86_64.c +++ b/x86_64.c @@ -1538,11 +1538,8 @@ x86_64_ist_init(void) if (ms->stkinfo.ebase[c][i]) ms->stkinfo.ebase[c][i] -= ms->stkinfo.esize[i]; - ms->stkinfo.available[c][i] = TRUE; /* VC stack can be unmapped if SEV-ES is * disabled or not supported. */ - if (STREQ(ms->stkinfo.exception_stacks[i], "VC") && - !accessible(ms->stkinfo.ebase[c][i])) - ms->stkinfo.available[c][i] = FALSE; + ms->stkinfo.available[c][i] = accessible(ms->stkinfo.ebase[c][i]); } } Thanks! > Thanks > Lianbo > > !accessible(ms->stkinfo.ebase[c][i])) > > ms->stkinfo.available[c][i] = > > FALSE; > > } > > > > base-commit: f13853cef53f5c5463a51021edbc81977e2b1405 > > -- > > 2.31.1 > > -- Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ Contribution Guidelines: https://github.com/crash-utility/crash/wiki