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 424f188e62d9886ee7f6d2531547f09a0606747d..27017236485b98ffe7a174d311f71c2ed6fbbb12 100644 (file)
--- 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 de1018cc522b376fe958f561f26305c3a98fb2c4..e3d5d3823dac3be7de8c33fe88ceeee122bd182f 100644 (file)
--- 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 1b106fbcc567ab6acebac172c8e78b8f17c6d0da..ec3101f95e53224850a7a79fac6399064c714405 100644 (file)
--- 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)