Le 19/06/2023 à 11:47, Naveen N Rao a écrit :
> Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
> added ftrace support for ppc64 kernel images with a text section larger
> than 32MB. The approach itself isn't specific to ppc64, so extend the
> same to also work on ppc32.
>
> While at it, reduce the space reserved for the stub from 64 bytes to 32
> bytes since the different stub variants are all less than 8
> instructions.
>
> To reduce use of #ifdef, a stub implementation is provided for
> kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent
> errors on ppc32.
>
Reviewed-by: Christophe Leroy <christophe.le...@csgroup.eu>
> Signed-off-by: Naveen N Rao <nav...@kernel.org>
> ---
> arch/powerpc/include/asm/ftrace.h | 10 +++++--
> arch/powerpc/include/asm/sections.h | 2 ++
> arch/powerpc/kernel/trace/ftrace.c | 39 ++++++++++++++------------
> arch/powerpc/kernel/trace/ftrace_low.S | 6 ++--
> arch/powerpc/kernel/vmlinux.lds.S | 4 ---
> 5 files changed, 32 insertions(+), 29 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/ftrace.h
> b/arch/powerpc/include/asm/ftrace.h
> index 2edc6269b1a357..702aaf2efa966c 100644
> --- a/arch/powerpc/include/asm/ftrace.h
> +++ b/arch/powerpc/include/asm/ftrace.h
> @@ -124,15 +124,19 @@ static inline u8 this_cpu_get_ftrace_enabled(void)
> {
> return get_paca()->ftrace_enabled;
> }
> -
> -void ftrace_free_init_tramp(void);
> #else /* CONFIG_PPC64 */
> static inline void this_cpu_disable_ftrace(void) { }
> static inline void this_cpu_enable_ftrace(void) { }
> static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
> static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
> -static inline void ftrace_free_init_tramp(void) { }
> #endif /* CONFIG_PPC64 */
> +
> +#ifdef CONFIG_FUNCTION_TRACER
> +extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
> +void ftrace_free_init_tramp(void);
> +#else
> +static inline void ftrace_free_init_tramp(void) { }
> +#endif
> #endif /* !__ASSEMBLY__ */
>
> #endif /* _ASM_POWERPC_FTRACE */
> diff --git a/arch/powerpc/include/asm/sections.h
> b/arch/powerpc/include/asm/sections.h
> index 4e1f548c8d373d..ea26665f82cfc8 100644
> --- a/arch/powerpc/include/asm/sections.h
> +++ b/arch/powerpc/include/asm/sections.h
> @@ -74,6 +74,8 @@ static inline int overlaps_kernel_text(unsigned long start,
> unsigned long end)
> (unsigned long)_stext < end;
> }
>
> +#else
> +static inline unsigned long kernel_toc_addr(void) { BUILD_BUG(); return
> -1UL; }
> #endif
>
> #endif /* __KERNEL__ */
> diff --git a/arch/powerpc/kernel/trace/ftrace.c
> b/arch/powerpc/kernel/trace/ftrace.c
> index 5aa36272617a03..913c7aa63d3fa3 100644
> --- a/arch/powerpc/kernel/trace/ftrace.c
> +++ b/arch/powerpc/kernel/trace/ftrace.c
> @@ -707,11 +707,6 @@ void arch_ftrace_update_code(int command)
> ftrace_modify_all_code(command);
> }
>
> -#ifdef CONFIG_PPC64
> -#define PACATOC offsetof(struct paca_struct, kernel_toc)
> -
> -extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[];
> -
> void ftrace_free_init_tramp(void)
> {
> int i;
> @@ -725,28 +720,30 @@ void ftrace_free_init_tramp(void)
>
> int __init ftrace_dyn_arch_init(void)
> {
> - int i;
> unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
> -#ifdef CONFIG_PPC_KERNEL_PCREL
> + unsigned long addr = FTRACE_REGS_ADDR;
> + long reladdr;
> + int i;
> u32 stub_insns[] = {
> +#ifdef CONFIG_PPC_KERNEL_PCREL
> /* pla r12,addr */
> PPC_PREFIX_MLS | __PPC_PRFX_R(1),
> PPC_INST_PADDI | ___PPC_RT(_R12),
> PPC_RAW_MTCTR(_R12),
> PPC_RAW_BCTR()
> - };
> -#else
> - u32 stub_insns[] = {
> - PPC_RAW_LD(_R12, _R13, PACATOC),
> +#elif defined(CONFIG_PPC64)
> + PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct,
> kernel_toc)),
> PPC_RAW_ADDIS(_R12, _R12, 0),
> PPC_RAW_ADDI(_R12, _R12, 0),
> PPC_RAW_MTCTR(_R12),
> PPC_RAW_BCTR()
> - };
> +#else
> + PPC_RAW_LIS(_R12, 0),
> + PPC_RAW_ADDI(_R12, _R12, 0),
> + PPC_RAW_MTCTR(_R12),
> + PPC_RAW_BCTR()
> #endif
> -
> - unsigned long addr = FTRACE_REGS_ADDR;
> - long reladdr;
> + };
>
> if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
> for (i = 0; i < 2; i++) {
> @@ -763,10 +760,10 @@ int __init ftrace_dyn_arch_init(void)
> tramp[i][1] |= IMM_L(reladdr);
> add_ftrace_tramp((unsigned long)tramp[i]);
> }
> - } else {
> + } else if (IS_ENABLED(CONFIG_PPC64)) {
> reladdr = addr - kernel_toc_addr();
>
> - if (reladdr >= (long)SZ_2G || reladdr < -(long)SZ_2G) {
> + if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
> pr_err("Address of %ps out of range of kernel_toc.\n",
> (void *)addr);
> return -1;
> @@ -778,11 +775,17 @@ int __init ftrace_dyn_arch_init(void)
> tramp[i][2] |= PPC_LO(reladdr);
> add_ftrace_tramp((unsigned long)tramp[i]);
> }
> + } else {
> + for (i = 0; i < 2; i++) {
> + memcpy(tramp[i], stub_insns, sizeof(stub_insns));
> + tramp[i][0] |= PPC_HA(addr);
> + tramp[i][1] |= PPC_LO(addr);
> + add_ftrace_tramp((unsigned long)tramp[i]);
> + }
> }
>
> return 0;
> }
> -#endif
>
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> diff --git a/arch/powerpc/kernel/trace/ftrace_low.S
> b/arch/powerpc/kernel/trace/ftrace_low.S
> index 294d1e05958aae..2fc7dd0a5ae968 100644
> --- a/arch/powerpc/kernel/trace/ftrace_low.S
> +++ b/arch/powerpc/kernel/trace/ftrace_low.S
> @@ -10,19 +10,17 @@
> #include <asm/ppc-opcode.h>
> #include <asm/export.h>
>
> -#ifdef CONFIG_PPC64
> .pushsection ".tramp.ftrace.text","aw",@progbits;
> .globl ftrace_tramp_text
> ftrace_tramp_text:
> - .space 64
> + .space 32
> .popsection
>
> .pushsection ".tramp.ftrace.init","aw",@progbits;
> .globl ftrace_tramp_init
> ftrace_tramp_init:
> - .space 64
> + .space 32
> .popsection
> -#endif
>
> _GLOBAL(mcount)
> _GLOBAL(_mcount)
> diff --git a/arch/powerpc/kernel/vmlinux.lds.S
> b/arch/powerpc/kernel/vmlinux.lds.S
> index 13614f0b269cf4..1c5970df323366 100644
> --- a/arch/powerpc/kernel/vmlinux.lds.S
> +++ b/arch/powerpc/kernel/vmlinux.lds.S
> @@ -107,9 +107,7 @@ SECTIONS
> #endif
> /* careful! __ftr_alt_* sections need to be close to .text */
> *(.text.hot .text.hot.* TEXT_MAIN .text.fixup .text.unlikely
> .text.unlikely.* .fixup __ftr_alt_* .ref.text);
> -#ifdef CONFIG_PPC64
> *(.tramp.ftrace.text);
> -#endif
> NOINSTR_TEXT
> SCHED_TEXT
> LOCK_TEXT
> @@ -276,9 +274,7 @@ SECTIONS
> */
> . = ALIGN(PAGE_SIZE);
> _einittext = .;
> -#ifdef CONFIG_PPC64
> *(.tramp.ftrace.init);
> -#endif
> } :text
>
> /* .exit.text is discarded at runtime, not link time,
