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arm64/ftrace: Make function graph use ftrace directly

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As we do in commit 0c0593b45c ("x86/ftrace: Make function graph
use ftrace directly"), we don't need special hook for graph tracer,
but instead we use graph_ops:func function to install return_hooker.

Since commit 3b23e4991f ("arm64: implement ftrace with regs") add
implementation for FTRACE_WITH_REGS on arm64, we can easily adopt
the same cleanup on arm64.

And this cleanup only changes the FTRACE_WITH_REGS implementation,
so the mcount-based implementation is unaffected.

While in theory it would be possible to make a similar cleanup for
!FTRACE_WITH_REGS, this will require rework of the core code, and
so for now we only change the FTRACE_WITH_REGS implementation.

Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lore.kernel.org/r/20220420160006.17880-2-zhouchengming@bytedance.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Chengming Zhou 2022-04-21 00:00:06 +08:00 committed by Catalin Marinas
parent e999995c84
commit c4a0ebf87c
3 changed files with 24 additions and 17 deletions
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7
arch/arm64/include/asm/ftrace.h
View File

@ -80,8 +80,15 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
struct dyn_ftrace;
struct ftrace_ops;
struct ftrace_regs;
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
#define ftrace_init_nop ftrace_init_nop
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
#define ftrace_graph_func ftrace_graph_func
#endif
#define ftrace_return_address(n) return_address(n)

17
arch/arm64/kernel/entry-ftrace.S
View File

@ -97,12 +97,6 @@ SYM_CODE_START(ftrace_common)
SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
bl ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) // ftrace_graph_caller();
nop // If enabled, this will be replaced
// "b ftrace_graph_caller"
#endif
/*
* At the callsite x0-x8 and x19-x30 were live. Any C code will have preserved
* x19-x29 per the AAPCS, and we created frame records upon entry, so we need
@ -127,17 +121,6 @@ ftrace_common_return:
ret x9
SYM_CODE_END(ftrace_common)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
SYM_CODE_START(ftrace_graph_caller)
ldr x0, [sp, #S_PC]
sub x0, x0, #AARCH64_INSN_SIZE // ip (callsite's BL insn)
add x1, sp, #S_LR // parent_ip (callsite's LR)
ldr x2, [sp, #PT_REGS_SIZE] // parent fp (callsite's FP)
bl prepare_ftrace_return
b ftrace_common_return
SYM_CODE_END(ftrace_graph_caller)
#endif
#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
/*

17
arch/arm64/kernel/ftrace.c
View File

@ -268,6 +268,22 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
}
#ifdef CONFIG_DYNAMIC_FTRACE
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
/*
* When DYNAMIC_FTRACE_WITH_REGS is selected, `fregs` can never be NULL
* and arch_ftrace_get_regs(fregs) will always give a non-NULL pt_regs
* in which we can safely modify the LR.
*/
struct pt_regs *regs = arch_ftrace_get_regs(fregs);
unsigned long *parent = (unsigned long *)&procedure_link_pointer(regs);
prepare_ftrace_return(ip, parent, frame_pointer(regs));
}
#else
/*
* Turn on/off the call to ftrace_graph_caller() in ftrace_caller()
* depending on @enable.
@ -297,5 +313,6 @@ int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */