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    Subject[PATCH 09/11] x86_64: add function prototype recording support
    Date
    This patch implements the arch_fgraph_record_params() function for x86_64
    platform and deliver the return value of function to ftrace core part.

    Signed-off-by: Changbin Du <changbin.du@gmail.com>
    ---
    arch/x86/Kconfig | 1 +
    arch/x86/kernel/ftrace.c | 84 +++++++++++++++++++++++++++++++++++--
    arch/x86/kernel/ftrace_64.S | 4 +-
    3 files changed, 85 insertions(+), 4 deletions(-)

    diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
    index 222855cc0158..34e583bfdab8 100644
    --- a/arch/x86/Kconfig
    +++ b/arch/x86/Kconfig
    @@ -31,6 +31,7 @@ config X86_64
    select NEED_DMA_MAP_STATE
    select SWIOTLB
    select ARCH_HAS_SYSCALL_WRAPPER
    + select HAVE_FTRACE_FUNC_PROTOTYPE

    config FORCE_DYNAMIC_FTRACE
    def_bool y
    diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
    index a044734167af..fc0a062ce762 100644
    --- a/arch/x86/kernel/ftrace.c
    +++ b/arch/x86/kernel/ftrace.c
    @@ -31,6 +31,7 @@
    #include <asm/ftrace.h>
    #include <asm/nops.h>
    #include <asm/text-patching.h>
    +#include <asm-generic/dwarf.h>

    #ifdef CONFIG_DYNAMIC_FTRACE

    @@ -918,7 +919,8 @@ static void *addr_from_call(void *ptr)
    }

    void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
    - unsigned long frame_pointer);
    + unsigned long frame_pointer,
    + struct pt_regs *pt_regs);

    /*
    * If the ops->trampoline was not allocated, then it probably
    @@ -973,6 +975,82 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
    ops->trampoline = 0;
    }

    +#ifdef CONFIG_FTRACE_FUNC_PROTOTYPE
    +void arch_fgraph_record_params(struct ftrace_graph_ent *trace,
    + struct func_prototype *proto,
    + struct pt_regs *pt_regs)
    +{
    + int i;
    +
    + trace->nr_param = min(proto->nr_param, (uint8_t)FTRACE_MAX_FUNC_PARAMS);
    +
    + for (i = 0; i < trace->nr_param; i++) {
    + struct func_param *param = &proto->params[i];
    + unsigned int sz = FTRACE_PROTOTYPE_SIZE(param->type);
    + long off = (char)param->loc[1];
    + unsigned long value = 0;
    + bool good = true;
    +
    + if (sz > sizeof(value)) {
    + /* Don't record value of complex type. */
    + trace->param_types[i] = param->type;
    + trace->param_values[i] = 0;
    + continue;
    + }
    +
    + switch (param->loc[0]) {
    + case DW_OP_reg1:
    + value = pt_regs->dx;
    + break;
    + case DW_OP_reg2:
    + value = pt_regs->cx;
    + break;
    + case DW_OP_reg3:
    + value = pt_regs->bx;
    + break;
    + case DW_OP_reg4:
    + value = pt_regs->si;
    + break;
    + case DW_OP_reg5:
    + value = pt_regs->di;
    + break;
    + case DW_OP_reg6:
    + value = pt_regs->bp;
    + break;
    + case DW_OP_reg8:
    + value = pt_regs->r8;
    + break;
    + case DW_OP_reg9:
    + value = pt_regs->r9;
    + break;
    + case DW_OP_fbreg:
    + if (probe_kernel_read(&value,
    + (void *)pt_regs->bp + off,
    + sz))
    + good = false;
    + break;
    + case DW_OP_breg7:
    + if (probe_kernel_read(&value,
    + (void *)pt_regs->sp + off,
    + sz))
    + good = false;
    + break;
    + default:
    + /* unexpected loc expression */
    + good = false;
    + }
    +
    + trace->param_names[i] = param->name;
    + if (good) {
    + trace->param_types[i] = param->type;
    + trace->param_values[i] = value;
    + } else {
    + /* set the type to 0 so we skip it when printing. */
    + trace->param_types[i] = 0;
    + }
    + }
    +}
    +#endif /* CONFIG_FTRACE_FUNC_PROTOTYPE */
    #endif /* CONFIG_X86_64 */
    #endif /* CONFIG_DYNAMIC_FTRACE */

    @@ -1017,7 +1095,7 @@ int ftrace_disable_ftrace_graph_caller(void)
    * in current thread info.
    */
    void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
    - unsigned long frame_pointer)
    + unsigned long frame_pointer, struct pt_regs *pt_regs)
    {
    unsigned long old;
    int faulted;
    @@ -1072,7 +1150,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
    return;
    }

    - if (function_graph_enter(old, self_addr, frame_pointer, parent, NULL))
    + if (function_graph_enter(old, self_addr, frame_pointer, parent, pt_regs))
    *parent = old;
    }
    #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
    diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
    index 809d54397dba..e01d6358e859 100644
    --- a/arch/x86/kernel/ftrace_64.S
    +++ b/arch/x86/kernel/ftrace_64.S
    @@ -289,7 +289,8 @@ ENTRY(ftrace_graph_caller)

    leaq MCOUNT_REG_SIZE+8(%rsp), %rsi
    movq $0, %rdx /* No framepointers needed */
    - call prepare_ftrace_return
    + movq %rsp, %rcx /* the fourth parameter */
    + call prepare_ftrace_return

    restore_mcount_regs

    @@ -304,6 +305,7 @@ ENTRY(return_to_handler)
    movq %rax, (%rsp)
    movq %rdx, 8(%rsp)
    movq %rbp, %rdi
    + movq %rax, %rsi

    call ftrace_return_to_handler

    --
    2.20.1
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