[Crash-utility] Re: [PATCH v3] x86_64: Make ORC_REG_SP and ORC_REG_PREV_SP independent from kernel version

Hi Dave, On Sun, Aug 9, 2026 at 1:54 PM Dave Young <yangrr.2009(a)tsinghua.org.cn&gt; wrote: > > > > On 8/8/26 8:11 PM, Dave Young wrote: > > Hi Tao, > > > > On 8/6/26 8:16 AM, Tao Liu wrote: > >> Previously ORC_REG_SP and ORC_REG_PREV_SP will depend on kernel version > >> for their value, however this is fragile since distributions will > >> backport the upstream patch to a lower kernel version, thus break the > >> version assumption. > >> > >> This patch fixes by checking the value of ORC_REG_PREV_SP, which can be > >> get from orc_fp_entry. ORC_REG_PREV_SP's value can work as the indicator > >> of whether the current kernel have applied the upstream patch 1735858caa4b > >> ("objtool/x86: Reorder ORC register numbering"). > >> > >> Fixes: d0ee428664f9 ("x86_64: Fix "bt" command to use correct ORC register > >> values on Linux 7.1 and later") > >> > >> Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > >> --- > >> v3 -> v2: Remove data type query of orc_fp_entry, just use kernel_orc_entry_6_4 > >> which already contained in crash utility for bp_reg offset resolving. > >> --- > >> x86_64.c | 32 +++++++++++++++++++++++++------- > >> 1 file changed, 25 insertions(+), 7 deletions(-) > >> > >> diff --git a/x86_64.c b/x86_64.c > >> index 55648697baf3..d192f3bcdd20 100644 > >> --- a/x86_64.c > >> +++ b/x86_64.c > >> @@ -6661,6 +6661,9 @@ x86_64_ORC_init(void) > >> NULL > >> }; > >> struct ORC_data *orc; > >> + struct gnu_request request, *req; > >> + ulong value = 0; > >> + req = &request; > >> > >> MEMBER_OFFSET_INIT(inactive_task_frame_bp, "inactive_task_frame", "bp"); > >> MEMBER_OFFSET_INIT(inactive_task_frame_ret_addr, "inactive_task_frame", "ret_addr"); > >> @@ -6736,13 +6739,28 @@ x86_64_ORC_init(void) > >> if (orc->has_signal && !orc->has_end) > >> machdep->flags |= ORC_6_4; > >> > >> - /* See kernel commit 1735858caa4b */ > >> - if (THIS_KERNEL_VERSION >= LINUX(7,1,0)) { > >> - ORC_REG_SP = 3; > >> - ORC_REG_PREV_SP = 8; > >> - } else { > >> - ORC_REG_SP = 5; > >> - ORC_REG_PREV_SP = 1; > >> + /* Try get ORC_REG_(PREV)_SP */ > >> + ORC_REG_SP = 5; > >> + ORC_REG_PREV_SP = 1; > > > > How about use the newere values as default, and check the symbol data and set them as old ones if needed? > > Hmm, if change the order, the orc_fp_entry could not exist since it was introduced in 2025. Ok, unless you have some smarter idea, the patch looks good, please ignore the above comment. > OK, thanks Dave. I will take the original one. Thanks again for your comment and patch review! Thanks, Tao Liu > > Reviewed-by: Dave Young <yangrr.2009(a)tsinghua.org.cn&gt; > > Thanks >