From: Christophe Leroy <christophe.leroy@csgroup.eu>
Date: Tue, 3 Dec 2024 19:44:52 +0000 (+0100)
Subject: powerpc/static_call: Implement inline static calls
X-Git-Tag: io_uring-6.15-20250403~55^2~35
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=f50b45626e053dc10792c680cabbbadbf8c001e7;p=linux-block.git

powerpc/static_call: Implement inline static calls

Implement inline static calls:
- Put a 'bl' to the destination function ('b' if tail call)
- Put a 'nop' when the destination function is NULL ('blr' if tail call)
- Put a 'li r3,0' when the destination is the RET0 function and not
a tail call.

If the destination is too far (over the 32Mb limit), go via the
trampoline.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/3dbd0b2ba577c942729235d0211d04a406653d81.1733245362.git.christophe.leroy@csgroup.eu
---

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 424f188e62d9..27017236485b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -286,6 +286,7 @@ config PPC
 	select HAVE_STACKPROTECTOR		if PPC32 && $(cc-option,$(m32-flag) -mstack-protector-guard=tls -mstack-protector-guard-reg=r2 -mstack-protector-guard-offset=0)
 	select HAVE_STACKPROTECTOR		if PPC64 && $(cc-option,$(m64-flag) -mstack-protector-guard=tls -mstack-protector-guard-reg=r13 -mstack-protector-guard-offset=0)
 	select HAVE_STATIC_CALL			if PPC32
+	select HAVE_STATIC_CALL_INLINE		if PPC32
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_VIRT_CPU_ACCOUNTING
 	select HAVE_VIRT_CPU_ACCOUNTING_GEN
diff --git a/arch/powerpc/include/asm/static_call.h b/arch/powerpc/include/asm/static_call.h
index de1018cc522b..e3d5d3823dac 100644
--- a/arch/powerpc/include/asm/static_call.h
+++ b/arch/powerpc/include/asm/static_call.h
@@ -26,4 +26,6 @@
 #define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name)	__PPC_SCT(name, "blr")
 #define ARCH_DEFINE_STATIC_CALL_RET0_TRAMP(name)	__PPC_SCT(name, "b .+20")
 
+#define CALL_INSN_SIZE		4
+
 #endif /* _ASM_POWERPC_STATIC_CALL_H */
diff --git a/arch/powerpc/kernel/static_call.c b/arch/powerpc/kernel/static_call.c
index 1b106fbcc567..ec3101f95e53 100644
--- a/arch/powerpc/kernel/static_call.c
+++ b/arch/powerpc/kernel/static_call.c
@@ -15,7 +15,29 @@ void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
 
 	mutex_lock(&text_mutex);
 
-	if (tramp) {
+	if (site && tail) {
+		if (!func)
+			err = patch_instruction(site, ppc_inst(PPC_RAW_BLR()));
+		else if (is_ret0)
+			err = patch_branch(site, _ret0, 0);
+		else if (is_short)
+			err = patch_branch(site, _func, 0);
+		else if (tramp)
+			err = patch_branch(site, _tramp, 0);
+		else
+			err = 0;
+	} else if (site) {
+		if (!func)
+			err = patch_instruction(site, ppc_inst(PPC_RAW_NOP()));
+		else if (is_ret0)
+			err = patch_instruction(site, ppc_inst(PPC_RAW_LI(_R3, 0)));
+		else if (is_short)
+			err = patch_branch(site, _func, BRANCH_SET_LINK);
+		else if (tramp)
+			err = patch_branch(site, _tramp, BRANCH_SET_LINK);
+		else
+			err = 0;
+	} else if (tramp) {
 		if (func && !is_short) {
 			err = patch_ulong(tramp + PPC_SCT_DATA, _func);
 			if (err)