Messages in this thread | | | Date | Tue, 28 Mar 2023 15:02:39 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH v8 3/8] ARM: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL |
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On Tue, Mar 28, 2023 at 06:43:14AM -0700, Donglin Peng wrote: > The commit d4815c5d1bbd ("function_graph: Support recording and printing > the return value of function") laid the groundwork for the for the > funcgraph-retval, and this modification makes it available on the > ARM platform. > > We introduce a new structure called fgraph_ret_regs for the ARM platform > to hold return registers and the frame pointer. We then fill its content > in the return_to_handler and pass its address to the function > ftrace_return_to_handler to record the return value. > > Signed-off-by: Donglin Peng <pengdonglin@sangfor.com.cn> > --- > v8: > - Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL > --- > arch/arm/Kconfig | 1 + > arch/arm/include/asm/ftrace.h | 18 ++++++++++++++++++ > arch/arm/kernel/entry-ftrace.S | 6 +++++- > 3 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index e24a9820e12f..73061379855a 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -98,6 +98,7 @@ config ARM > select HAVE_FAST_GUP if ARM_LPAE > select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL > select HAVE_FUNCTION_ERROR_INJECTION > + select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER > select HAVE_FUNCTION_GRAPH_TRACER > select HAVE_FUNCTION_TRACER if !XIP_KERNEL > select HAVE_GCC_PLUGINS > diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h > index 7e9251ca29fe..2ab4bee21d79 100644 > --- a/arch/arm/include/asm/ftrace.h > +++ b/arch/arm/include/asm/ftrace.h > @@ -77,4 +77,22 @@ static inline bool arch_syscall_match_sym_name(const char *sym, > > #endif /* ifndef __ASSEMBLY__ */ > > + > +#ifndef __ASSEMBLY__ > +struct fgraph_ret_regs { > + unsigned long regs[4]; > + unsigned long fp; > +}; > + > +static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs) > +{ > + return ret_regs->regs[0]; > +} > + > +static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs) > +{ > + return ret_regs->fp; > +} > +#endif > + > #endif /* _ASM_ARM_FTRACE */ > diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S > index 3e7bcaca5e07..5f1e74555b25 100644 > --- a/arch/arm/kernel/entry-ftrace.S > +++ b/arch/arm/kernel/entry-ftrace.S > @@ -257,11 +257,15 @@ ENDPROC(ftrace_graph_regs_caller) > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > ENTRY(return_to_handler) > + sub sp, sp, #4 > stmdb sp!, {r0-r3} > - add r0, sp, #16 @ sp at exit of instrumented routine > + add r0, sp, #20 @ sp at exit of instrumented routine > + str r0, [sp, #16] > + mov r0, sp
1) EABI wants the stack to be aligned to 8 bytes. 2) We can do better than this.
mov ip, sp stmdb sp!, {r0-r3, ip, lr} mov r0, sp
> bl ftrace_return_to_handler > mov lr, r0 @ r0 has real ret addr > ldmia sp!, {r0-r3}
ldmia sp, {r0-r3} @ since we need to manually adjust sp,
> + add sp, sp, #4 @ skip fp
add sp, sp, #4 * 6 @ restore stack pointer here
> ret lr > ENDPROC(return_to_handler) > #endif > -- > 2.25.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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