Kernel bug. h and GCC inline assembly learning, kernel bug. hgcc inline

Kernel bug. h and GCC inline assembly learning, kernel bug. hgcc inline

All the learning content is in the annotations. In my learning process, after seeing this code segment, all I need is to learn it roughly. Strive to understand the entire part.
The following shows my learning code:

# Ifndef _ i1__bug_h # define _ i1__bug_h/** Tell the user there is some problem. * Tell The user that there are some problems * the offending file and line are encoded after the "officially * undefined" opcode for parsing in The trap handler. ** problematic files and lines are encoded after the "officially undefined" operation code to be resolved in a trap * Handler. * // *** 1 :__ asm __: gcc inline assembly method * Common gcc inline assembly method: * Embedded Assembly Syntax: _ asm _ (Assembly statement template: Output part: input part: Damage description part) * consists of four parts: Assembly statement template, output part, input part, damage description section. * use the ":" format for each part. The Assembly statement template is required. The other three parts are optional. * if the latter part is used, and the former part is empty, you also need to use the ":" format. The corresponding part of the content is blank ** 2: ud2 command is a software instruction that allows the CPU to generate invalid opcode exception, * If the kernel finds this exception on the CPU, it immediately stops running. * 3 :__ volatile _ tells the compiler that none of the commands currently written are immutable, including the order, * If _ volatile _ is not included, the optimized Type Selection-O is used during gcc compilation, * The compiler will optimize the code according to its own optimization rules. * 4: The following may not be clear after inline is added. In this way, the Assembly command is used only: * ud2 ;*. word % c0 ;*. long % c1; *: "I" (_ LINE _), "I" (_ FILE _); ** as shown in the code above: * ud2; command to stop CPU running *. word % c0; The placeholder % c0 is a word *. long % c1; The placeholder % c1 is a long integer * ::; the output part in the middle is omitted * "I" (_ LINE __), "I" (_ FILE _) Replace the placeholder % c0, % c1, with (_ LINE _) and (_ FILE _) * respectively, "I" indicates the number of integers ** 5: the abbreviation of some register constraints * r: I/O, indicating that a general register is used, selected by GCC in % eax/% ax/% al, % ebx/% bx/% bl, % ecx/% cx/% cl, % edx/% dx/% dl a gcc considers it appropriate; * q: I/O indicates that a general register is used, which has the same meaning as r. * g: I/O indicates that registers or memory addresses are used. * m: I/O, memory Address used; * a: I/O, % eax/% ax/% al; * B: I/O, % ebx/% bx/% bl; * c: I/O, % ecx/% cx/% cl; * d: I/O, % edx/% dx/% dl; * D: I/O, % edi/% di; * S: I/O, % esi/% si is used; * f: I/O indicates that floating point registers are used; * t: I/O indicates that the first floating point register is used; * u: i/O indicates that the second floating point register is used. * A: I/O indicates that % eax and % edx are combined into A 64-bit integer. * o: i/O, which indicates the offset of one memory location; * V: I/O, which indicates that only one direct memory location is used; * I: I/O, indicates the immediate number of an integer; * n: I/O indicates the immediate number with a known integer; * F: I/O, indicates the immediate Number of floating point types; *****/# ifdef CONFIG_BUG # define HAVE_ARCH_BUG # ifdef CONFIG_DEBUG_BUGVERBOSE # define BUG () \ _ asm _ volatile _ ("ud2 \ n" \ "\ t. word % c0 \ n "\" \ t. long % c1 \ n "\:" I "(_ LINE _)," I "(_ FILE _) # else # define BUG () _ asm _ volatile _ ("ud2 \ n") // directly stop the CPU running # endif # include <asm-generic/bug. h> # endif

In the process of GCC inline assembly, we can see that GCC only supports AT&T assembly language, and we know some features about AT&T assembly language. I have studied X86 assembly before and found many differences. By reading an article, I made a general summary of it, which is more valuable.
Comparison between AT&T and intel