2023-09-12 21:16:54

by Josh Poimboeuf

[permalink] [raw]
Subject: [PATCH] objtool: Fix _THIS_IP_ detection for cold functions

Cold functions and their non-cold counterparts can use _THIS_IP_ to
reference each other. Don't warn about !ENDBR in that case.

Note that for GCC this is currently irrelevant in light of the following
commit

c27cd083cfb9 ("Compiler attributes: GCC cold function alignment workarounds")

which disabled cold functions in the kernel. However this may still be
possible with Clang.

Fixes several warnings like the following:

drivers/scsi/bnx2i/bnx2i.prelink.o: warning: objtool: bnx2i_hw_ep_disconnect+0x19d: relocation to !ENDBR: bnx2i_hw_ep_disconnect.cold+0x0
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr4_event.cold+0x28: relocation to !ENDBR: ipvlan_addr4_event+0xda
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr6_event.cold+0x26: relocation to !ENDBR: ipvlan_addr6_event+0xb7
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_set_ringparam.cold+0x17: relocation to !ENDBR: tg3_set_ringparam+0x115
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_self_test.cold+0x17: relocation to !ENDBR: tg3_self_test+0x2e1
drivers/target/iscsi/cxgbit/cxgbit.prelink.o: warning: objtool: __cxgbit_free_conn.cold+0x24: relocation to !ENDBR: __cxgbit_free_conn+0xfb
net/can/can.prelink.o: warning: objtool: can_rx_unregister.cold+0x2c: relocation to !ENDBR: can_rx_unregister+0x11b
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_spq_post+0xc0: relocation to !ENDBR: qed_spq_post.cold+0x9a
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_iwarp_ll2_comp_syn_pkt.cold+0x12f: relocation to !ENDBR: qed_iwarp_ll2_comp_syn_pkt+0x34b
net/tipc/tipc.prelink.o: warning: objtool: tipc_nametbl_publish.cold+0x21: relocation to !ENDBR: tipc_nametbl_publish+0xa6

Signed-off-by: Josh Poimboeuf <[email protected]>
---
tools/objtool/check.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 1384090530db..e308d1ba664e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4333,7 +4333,8 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
continue;
}

- if (insn_func(dest) && insn_func(dest) == insn_func(insn)) {
+ if (insn_func(dest) && insn_func(insn) &&
+ insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
/*
* Anything from->to self is either _THIS_IP_ or
* IRET-to-self.
--
2.41.0


Subject: [tip: objtool/urgent] objtool: Fix _THIS_IP_ detection for cold functions

The following commit has been merged into the objtool/urgent branch of tip:

Commit-ID: 72178d5d1a38dd185d1db15f177f2d122ef10d9b
Gitweb: https://git.kernel.org/tip/72178d5d1a38dd185d1db15f177f2d122ef10d9b
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Mon, 11 Sep 2023 16:56:13 -07:00
Committer: Ingo Molnar <[email protected]>
CommitterDate: Tue, 12 Sep 2023 08:16:54 +02:00

objtool: Fix _THIS_IP_ detection for cold functions

Cold functions and their non-cold counterparts can use _THIS_IP_ to
reference each other. Don't warn about !ENDBR in that case.

Note that for GCC this is currently irrelevant in light of the following
commit

c27cd083cfb9 ("Compiler attributes: GCC cold function alignment workarounds")

which disabled cold functions in the kernel. However this may still be
possible with Clang.

Fixes several warnings like the following:

drivers/scsi/bnx2i/bnx2i.prelink.o: warning: objtool: bnx2i_hw_ep_disconnect+0x19d: relocation to !ENDBR: bnx2i_hw_ep_disconnect.cold+0x0
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr4_event.cold+0x28: relocation to !ENDBR: ipvlan_addr4_event+0xda
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr6_event.cold+0x26: relocation to !ENDBR: ipvlan_addr6_event+0xb7
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_set_ringparam.cold+0x17: relocation to !ENDBR: tg3_set_ringparam+0x115
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_self_test.cold+0x17: relocation to !ENDBR: tg3_self_test+0x2e1
drivers/target/iscsi/cxgbit/cxgbit.prelink.o: warning: objtool: __cxgbit_free_conn.cold+0x24: relocation to !ENDBR: __cxgbit_free_conn+0xfb
net/can/can.prelink.o: warning: objtool: can_rx_unregister.cold+0x2c: relocation to !ENDBR: can_rx_unregister+0x11b
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_spq_post+0xc0: relocation to !ENDBR: qed_spq_post.cold+0x9a
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_iwarp_ll2_comp_syn_pkt.cold+0x12f: relocation to !ENDBR: qed_iwarp_ll2_comp_syn_pkt+0x34b
net/tipc/tipc.prelink.o: warning: objtool: tipc_nametbl_publish.cold+0x21: relocation to !ENDBR: tipc_nametbl_publish+0xa6

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/d8f1ab6a23a6105bc023c132b105f245c7976be6.1694476559.git.jpoimboe@kernel.org
---
tools/objtool/check.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 1384090..e308d1b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4333,7 +4333,8 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
continue;
}

- if (insn_func(dest) && insn_func(dest) == insn_func(insn)) {
+ if (insn_func(dest) && insn_func(insn) &&
+ insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
/*
* Anything from->to self is either _THIS_IP_ or
* IRET-to-self.