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powerpc/static_call: Implement inline static calls

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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
This commit is contained in:
Christophe Leroy
2024-12-03 20:44:52 +01:00
committed by Madhavan Srinivasan
parent 6626f98ed5
commit f50b45626e
3 changed files with 26 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/Kconfig
View File

@@ -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

2
arch/powerpc/include/asm/static_call.h
View File

@@ -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 */

24
arch/powerpc/kernel/static_call.c
View File

@@ -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)