linux-kernel - [PATCH v2 6/7] static_call_inline: Provide trampoline address when updating sites

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Message-Id: <5dbe60ab94ea25eb1c1fa08ac3a2d20e870c7969.1657301423.git.christophe.leroy@csgroup.eu>
Date:   Fri,  8 Jul 2022 19:31:25 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>, sv@...ux.ibm.com,
        agust@...x.de, jpoimboe@...nel.org, peterz@...radead.org,
        jbaron@...mai.com, rostedt@...dmis.org, ardb@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        x86@...nel.org, chenzhongjin@...wei.com
Subject: [PATCH v2 6/7] static_call_inline: Provide trampoline address when updating sites

In preparation of support of inline static calls on powerpc, provide
trampoline address when updating sites, so that if the destination
function is too far for a direct function call, the call site will
be patched with a call to the trampoline.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/x86/kernel/static_call.c | 2 +-
 kernel/static_call_inline.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
index aa72cefdd5be..4db30b0ea71c 100644
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -102,7 +102,7 @@ void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
 {
 	mutex_lock(&text_mutex);
 
-	if (tramp) {
+	if (tramp && !site) {
 		__static_call_validate(tramp, true, true);
 		__static_call_transform(tramp, __sc_insn(!func, true), func);
 	}
diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
index dc5665b62814..b5de9d92fa4e 100644
--- a/kernel/static_call_inline.c
+++ b/kernel/static_call_inline.c
@@ -195,7 +195,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
 				continue;
 			}
 
-			arch_static_call_transform(site_addr, NULL, func,
+			arch_static_call_transform(site_addr, tramp, func,
 						   static_call_is_tail(site));
 		}
 	}
-- 
2.36.1