diff options
Diffstat (limited to 'print.html')
| -rw-r--r-- | print.html | 305 |
1 files changed, 272 insertions, 33 deletions
@@ -32,10 +32,11 @@ <!-- Custom theme stylesheets --> - <!-- Provide site root to javascript --> + <!-- Provide site root and default themes to javascript --> <script> - var path_to_root = ""; - var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light"; + const path_to_root = ""; + const default_light_theme = "light"; + const default_dark_theme = "navy"; </script> <!-- Start loading toc.js asap --> <script src="toc.js"></script> @@ -45,8 +46,8 @@ <!-- Work around some values being stored in localStorage wrapped in quotes --> <script> try { - var theme = localStorage.getItem('mdbook-theme'); - var sidebar = localStorage.getItem('mdbook-sidebar'); + let theme = localStorage.getItem('mdbook-theme'); + let sidebar = localStorage.getItem('mdbook-sidebar'); if (theme.startsWith('"') && theme.endsWith('"')) { localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1)); @@ -60,7 +61,8 @@ <!-- Set the theme before any content is loaded, prevents flash --> <script> - var theme; + const default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? default_dark_theme : default_light_theme; + let theme; try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { } if (theme === null || theme === undefined) { theme = default_theme; } const html = document.documentElement; @@ -73,8 +75,8 @@ <!-- Hide / unhide sidebar before it is displayed --> <script> - var sidebar = null; - var sidebar_toggle = document.getElementById("sidebar-toggle-anchor"); + let sidebar = null; + const sidebar_toggle = document.getElementById("sidebar-toggle-anchor"); if (document.body.clientWidth >= 1080) { try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { } sidebar = sidebar || 'visible'; @@ -110,6 +112,7 @@ <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> + <li role="none"><button role="menuitem" class="theme" id="default_theme">Auto</button></li> <li role="none"><button role="menuitem" class="theme" id="light">Light</button></li> <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> @@ -1426,7 +1429,7 @@ eval strace -f (find /dev -name 'std*' | xargs -I {} echo -P {}) ls # eval strace -f -P /dev/stdin -P /dev/stdout -P /dev/stderr ls </code></pre> <div style="break-before: page; page-break-before: always;"></div><h1 id="grep1"><a class="header" href="#grep1">grep(1)</a></h1> -<pre><code>sort [opts] [pattern] [files] +<pre><code>grep [opts] [pattern] [files] -e <pattern> pattern to search for (can be supplied multiple times) -i ignore case in patterns -v invert match @@ -4168,6 +4171,7 @@ objdump -C --disassemble=foo::bar <bin> <li><a href="development/./glibc.html">glibc</a></li> <li><a href="development/./gcc.html">gcc</a></li> <li><a href="development/./gas.html">gas</a></li> +<li><a href="development/./ld.html">ld</a></li> <li><a href="development/./git.html">git</a></li> <li><a href="development/./cmake.html">cmake</a></li> <li><a href="development/./make.html">make</a></li> @@ -5245,8 +5249,18 @@ run1: <div style="break-before: page; page-break-before: always;"></div><h1 id="gas"><a class="header" href="#gas">gas</a></h1> <h2 id="frequently-used-directives"><a class="header" href="#frequently-used-directives">Frequently used directives</a></h2> <ul> -<li> -<p><code>.byte</code>, <code>.2byte</code>, <code>.4byte</code>, <code>.8byte</code> to define a N byte value</p> +<li><code>.section</code> to define a section (elf files) +<pre><code class="language-x86asm">.section .text.foo, "ax", @progbits +; defines section named .text.foo with alloc+exec perms + +.section .data.foo, "aw", @progbits +; defines section named .data.foo with alloc+write perms + +.section .rodata.foo, "a", @progbits +; defines section named .rodata.foo with alloc perms +</code></pre> +</li> +<li><code>.byte</code>, <code>.2byte</code>, <code>.4byte</code>, <code>.8byte</code> to define a N byte value <pre><code class="language-x86asm">.byte 0xaa .2byte 0xaabb .2byte 0xaa, 0xbb @@ -5254,19 +5268,16 @@ run1: .8byte 0xaabbccdd11223344 </code></pre> </li> -<li> -<p><code>.ascii</code> to define an ascii string</p> +<li><code>.ascii</code> to define an ascii string <pre><code class="language-x86asm">.ascii "foo" ; allocates 3 bytes </code></pre> </li> -<li> -<p><code>.asciz</code> to define an ascii string with <code>'\0'</code> terminator</p> +<li><code>.asciz</code> to define an ascii string with <code>'\0'</code> terminator <pre><code class="language-x86asm">.asciz "foo" ; allocates 4 bytes (str + \0) </code></pre> </li> -<li> -<p><code>.macro</code> to define assembler macros. Arguments are accessed with the -<code>\arg</code> syntax.</p> +<li><code>.macro</code> to define assembler macros. Arguments are accessed with the +<code>\arg</code> syntax. <pre><code class="language-x86asm">.macro defstr name str \name: .ascii "\str" @@ -5281,16 +5292,241 @@ defstr foo, "foobar" <p>Use <code>\()</code> to concatenate macro argument and literal.</p> </blockquote> </li> -<li> -<p><a href="https://sourceware.org/binutils/docs/as">GNU Assembler</a></p> -</li> -<li> -<p><a href="https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops">GNU Assembler Directives</a></p> +<li><code>.rept</code> to repeat a sequence of lines between <code>.rept</code> and <code>.endr</code>. +<pre><code class="language-x86asm">.rept 4 +.4byte 123 +.endr +</code></pre> </li> -<li> -<p><a href="https://sourceware.org/binutils/docs/as/i386_002dDependent.html">GNU Assembler <code>x86_64</code> dependent features</a></p> +<li><code>.fill cnt, elem_size, val</code> write <code>cnt</code> times <code>val</code> with element size <code>elem_size</code>. For example one can use it to create a mbr boot record (magic number 0xaa55 at byte 511, 512). +<pre><code class="language-x86asm">.section .boot, "ax", @progbits +; some code .. +.4byte 0xff + +.fill 510 - (. - .boot), 1, 0x00 +.2byte 0xaa55 + +; as foo.s && objdump -j .boot -s +; Contents of section .boot: +; 0000 ff000000 00000000 00000000 00000000 +; .. +; 01f0 00000000 00000000 00000000 000055aa +</code></pre> +<blockquote> +<p>Here <code>.</code> stands for the current location counter.</p> +</blockquote> </li> </ul> +<h2 id="references-4"><a class="header" href="#references-4">References</a></h2> +<ul> +<li><a href="https://sourceware.org/binutils/docs/as">GNU Assembler</a></li> +<li><a href="https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops">GNU Assembler Directives</a></li> +<li><a href="https://sourceware.org/binutils/docs/as/i386_002dDependent.html">GNU Assembler <code>x86_64</code> dependent features</a></li> +</ul> +<div style="break-before: page; page-break-before: always;"></div><h1 id="ld1"><a class="header" href="#ld1">ld(1)</a></h1> +<pre><code>ld [opts] files... + -T <script> use <script> as linker script + --trace report each file the linker touches + --start-group archives --end-group + search archives repearepeatedly until no new + undefined references are created + (eg helpfull with list of static libraries) +</code></pre> +<h2 id="linker-script"><a class="header" href="#linker-script">Linker Script</a></h2> +<p><code>output</code> sections are defined as follows (full description at <a href="https://sourceware.org/binutils/docs/ld/Output-Section-Attributes.html">output +section</a> and <a href="https://sourceware.org/binutils/docs/ld/Input-Section.html">input section</a>).</p> +<pre><code>section_name [vaddr] : [AT(paddr)] { + file_pattern (section_pattern) +} +</code></pre> +<p>The following gives an example of an <code>output</code> section with two <code>input</code> section rules.</p> +<pre><code>.foo : { + abc.o (.foo) + *.o (.foo.*) +} +</code></pre> +<h3 id="example-virtual-vs-physical-load-address"><a class="header" href="#example-virtual-vs-physical-load-address">Example: virtual vs physical (load) address</a></h3> +<p>Sometimes code is initially located at a different location as when being run. +For example in embedded cases, where code may initially resides in a <em>rom</em> and +startup code will copy a section with writable <em>data</em> into <em>ram</em>. Code accessing +the writable data accesses the data in the <em>ram</em>.</p> +<p>In this case we need different addresses for the same data.</p> +<ul> +<li>The <code>virtual</code> or <em>runtime</em> address, this is the address used when the linker +resolves accesses to the data. Hence, this is the address the data will have +when the code is running.</li> +<li>The <code>physical</code> or <em>load</em> address, this is the address the data is stored at +initially. Startup code typically copies the initial values from the +<code>physical</code> to the <code>virtual</code> address.</li> +</ul> +<p>The following shows an example linker script which uses <em>virtual</em> and <em>physical</em> +addresses. The full source files can be found <a href="https://github.com/johannst/notes/tree/master/src/development/ld">here</a>.</p> +<pre><code>OUTPUT_FORMAT(elf64-x86-64) +ENTRY(_entry) + +SECTIONS { + /* Set the initial location counter (vaddr) */ + . = 0x00800000; + + /* Create .text output section at current vaddr */ + .text : { + *(.text*) + } + + ASSERT(. == 0x00800000 + SIZEOF(.text), "inc loc counter automatically") + + /* Create .data section at location counter aligned to the next 0x100 (vaddr) */ + /* Set the load address to 0x00100000 (paddr) */ + .data ALIGN(0x100) : AT(0x00100000) { + HIDDEN(_data_vaddr = .); + HIDDEN(_data_paddr = LOADADDR(.data)); + *(.data*) + } + + /* Create .rodata with explicit vaddr */ + /* Re-adjust the paddr location counter */ + .rodata 0x00804000 : AT(ADDR(.rodata)) { + *(.rodata*) + } + + ASSERT(. == 0x00804000 + SIZEOF(.rodata), "inc loc counter automatically") + + .stack ALIGN (0x1000) : { + . += 0x1000; + HIDDEN(_stack_top = .); + } + + /DISCARD/ : { + *(.*) + } +} + +/* Some example assertions */ +ASSERT(ADDR(.data) != LOADADDR(.data), "DATA vaddr and paddr must be different") +ASSERT(SIZEOF(.stack) == 0x1000, "STACK section must be 0x1000") +</code></pre> +<p>We can use the following assembly snippet to explore the linker script.</p> +<pre><code class="language-x86asm">.section .text, "ax", @progbits +.global _entry +_entry: + mov $_stack_top, %rsp + mov $asm_array, %rax + mov (asm_len), %eax + + hlt + jmp _entry + +.section .data.asm, "aw", @progbits +asm_array: + .4byte 0xa + .4byte 0xb + .4byte 0xc + .4byte 0xd +.rept 4 + .4byte 0xff +.endr + +.section .rodata.asm, "a", @progbits +asm_len: + .4byte 8 +</code></pre> +<blockquote> +<p><code>gcc -c data.S && ld -o link-nomem -T link-nomem.ld data.o</code></p> +</blockquote> +<p>The elf load segments show the difference in <em>physical</em> and <em>virtual</em> address +for the segment containing the <code>.data</code> section.</p> +<pre><code class="language-sh">> readelf -W -l link-nomem +# There are 4 program headers, starting at offset 64 +# +# Program Headers: +# Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align +# LOAD 0x001100 0x0000000000800100 0x0000000000100000 0x000020 0x000020 RW 0x1000 +# LOAD 0x002000 0x0000000000800000 0x0000000000800000 0x000018 0x000018 R E 0x1000 +# LOAD 0x003000 0x0000000000804000 0x0000000000804000 0x000004 0x000004 R 0x1000 +# LOAD 0x000000 0x0000000000805000 0x0000000000805000 0x000000 0x001000 RW 0x1000 +# +# Section to Segment mapping: +# Segment Sections... +# 00 .data +# 01 .text +# 02 .rodata +# 03 .stack +</code></pre> +<p>Startup code could copy data from <code>_data_paddr</code> to <code>_data_vaddr</code>.</p> +<pre><code class="language-sh">> nm link-nomem +# 0000000000800100 d asm_array +# 0000000000804000 r asm_len +# 0000000000100000 a _data_paddr +# 0000000000800100 d _data_vaddr +# 0000000000800000 T _entry +# 0000000000806000 b _stack_top +</code></pre> +<p>The linker resolves symbols to their <em>virtual</em> address, this can be seen by the +access to the <code>asm_array</code> variable.</p> +<pre><code class="language-sh">> objdump -d link-nomem +# Disassembly of section .text: +# +# 0000000000800000 <_entry>: +# 800000: 48 c7 c4 00 60 80 00 mov $0x806000,%rsp +# 800007: 48 c7 c0 00 01 80 00 mov $0x800100,%rax ;; mov $asm_array, %rax +# 80000e: 8b 04 25 00 40 80 00 mov 0x804000,%eax +# 800015: f4 hlt +# 800016: eb e8 jmp 800000 <_entry> +</code></pre> +<p>The following linker script shows an example with the <code>MEMORY</code> command.</p> +<pre><code>OUTPUT_FORMAT(elf64-x86-64) +ENTRY(_entry) + +MEMORY { + ROM : ORIGIN = 0x00100000, LENGTH = 0x4000 + RAM : ORIGIN = 0x00800000, LENGTH = 0x4000 +} + +SECTIONS { + /* Create .text output section at ROM (vaddr) */ + .text : { + *(.text*) + } > ROM + + ASSERT(. == ORIGIN(ROM) + SIZEOF(.text), "inc loc counter automatically") + + /* Create .data output section at RAM (vaddr) */ + /* Set load addr to ROM, right after .text (paddr) */ + .data : { + HIDDEN(_data_vaddr = .); + HIDDEN(_data_paddr = LOADADDR(.data)); + *(.data*) + } > RAM AT > ROM + + /* Append .rodata output section at ROM (vaddr) */ + .rodata : { + *(.rodata*) + } > ROM + + /* Append .stack output section at RAM (vaddr) aligned up to next 0x1000 */ + .stack : ALIGN (0x1000) { + . += 0x1000; + HIDDEN(_stack_top = .); + } > RAM + + /DISCARD/ : { + *(.*) + } +} + +/* Some example assertions */ +ASSERT(ADDR(.data) != LOADADDR(.data), "DATA vaddr and paddr must be different") +ASSERT(ADDR(.rodata) == LOADADDR(.rodata), "RODATA vaddr and paddr must be euqal") +ASSERT(ADDR(.stack) == ORIGIN(RAM) + 0x1000, "STACK section must aligned to 0x1000") +ASSERT(SIZEOF(.stack) == 0x1000, "STACK section must be 0x1000") +</code></pre> +<h2 id="references-5"><a class="header" href="#references-5">References</a></h2> +<ul> +<li><a href="https://sourceware.org/binutils/docs/ld/">ld manual</a></li> +<li><a href="https://sourceware.org/binutils/docs/ld/Input-Section.html">ld script: input sections</a></li> +<li><a href="https://sourceware.org/binutils/docs/ld/Output-Section-Attributes.html">ld script: output sections</a></li> +<li><a href="https://github.com/johannst/notes/tree/master/src/development/ld">notes/ld example files</a></li> +</ul> <div style="break-before: page; page-break-before: always;"></div><h1 id="git1"><a class="header" href="#git1">git(1)</a></h1> <h2 id="working-areas"><a class="header" href="#working-areas">Working areas</a></h2> <pre><code class="language-text">+-------------------+ --- stash -----> +-------+ @@ -6244,7 +6480,7 @@ func_v0 func_v1 func_v2 </code></pre> -<h2 id="references-4"><a class="header" href="#references-4">References</a></h2> +<h2 id="references-6"><a class="header" href="#references-6">References</a></h2> <ul> <li><a href="https://akkadia.org/drepper/symbol-versioning">ELF Symbol Versioning</a></li> <li><a href="https://sourceware.org/binutils/docs/ld/VERSION.html">Binutils ld: Symbol Versioning</a></li> @@ -6648,7 +6884,7 @@ journalctl --user -u test -n 5 --disk-usage Show current disk usage --vacuum-size=<size> Reduce journal log to <size> (K/M/G) </code></pre> -<h2 id="references-5"><a class="header" href="#references-5">References</a></h2> +<h2 id="references-7"><a class="header" href="#references-7">References</a></h2> <ul> <li><a href="https://www.man7.org/linux/man-pages/man5/systemd.unit.5.html">man systemd.unit(5)</a></li> <li><a href="https://www.man7.org/linux/man-pages/man5/systemd.service.5.html">man systemd.service(5)</a></li> @@ -7031,7 +7267,7 @@ group::r-x mask::r-x other::rwx </code></pre> -<h2 id="references-6"><a class="header" href="#references-6">References</a></h2> +<h2 id="references-8"><a class="header" href="#references-8">References</a></h2> <ul> <li><a href="https://www.man7.org/linux/man-pages/man5/acl.5.html">acl(5)</a></li> <li><a href="https://www.man7.org/linux/man-pages/man1/getfacl.1.html">getfacl(1)</a></li> @@ -7328,6 +7564,9 @@ lp -d PRINTER FILE -o sides=one-sided print front-page only -o sides=two-sided-long-edge print duplex +# Show job queue +lpq -P PRINTER + # Remove pending print job. lprm JOOBID </code></pre> @@ -7566,7 +7805,7 @@ firewall-cmd --remove-port 8000/tcp # Remove rich rule. firewall-cmd --remove-rich-rule 'rule family="ipv4" forward-port port="80" protocol="tcp" to-port="8080"' </code></pre> -<h2 id="references-7"><a class="header" href="#references-7">References</a></h2> +<h2 id="references-9"><a class="header" href="#references-9">References</a></h2> <ul> <li>man <a href="https://firewalld.org/documentation/man-pages/firewall-cmd.html">firewall-cmd(1)</a></li> <li>man <a href="https://firewalld.org/documentation/man-pages/firewalld.html">firewalld(1)</a></li> @@ -9109,7 +9348,7 @@ address translation.</p> <p>The example in <a href="arch/x86/seg/seg.c">seg.c</a> shows how to set the <code>gs</code> base address and to relative accesses.</p> </blockquote> -<h2 id="references-8"><a class="header" href="#references-8">References</a></h2> +<h2 id="references-10"><a class="header" href="#references-10">References</a></h2> <ul> <li><a href="https://gitlab.com/x86-psABIs/x86-64-ABI">SystemV AMD64 ABI</a></li> <li><a href="https://www.amd.com/system/files/TechDocs/24592.pdf">AMD64 Vol1: Application Programming</a></li> @@ -9382,7 +9621,7 @@ Hi ASM-World! distributions. Explicitly specifying the dynamic linker should not be required when compiling natively on arm64.</p> </blockquote> -<h2 id="references-9"><a class="header" href="#references-9">References</a></h2> +<h2 id="references-11"><a class="header" href="#references-11">References</a></h2> <ul> <li><a href="https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst">Procedure Call Standard ARM64</a></li> <li><a href="https://developer.arm.com/documentation/den0024/latest">ARMv8-A Programmer's Guide</a></li> @@ -9627,7 +9866,7 @@ Hi ASM-World! distributions. Explicitly specifying the dynamic linker should not be required when compiling natively on arm.</p> </blockquote> -<h2 id="references-10"><a class="header" href="#references-10">References</a></h2> +<h2 id="references-12"><a class="header" href="#references-12">References</a></h2> <ul> <li><a href="https://github.com/ARM-software/abi-aa/blob/master/aapcs32/aapcs32.rst">Procedure Call Standard ARM</a></li> <li><a href="https://developer.arm.com/documentation/den0013/latest">ARMv7-A Programmer's Guide</a></li> @@ -9708,7 +9947,7 @@ distributions. Explicitly specifying the dynamic linker should not be required when compiling natively on riscv.</p> <p>Select dynamic linker according to abi used during compile & link.</p> </blockquote> -<h2 id="references-11"><a class="header" href="#references-11">References</a></h2> +<h2 id="references-13"><a class="header" href="#references-13">References</a></h2> <ul> <li><a href="https://sourceware.org/binutils/docs/as">GNU Assembler</a></li> <li><a href="https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops">GNU Assembler Directives</a></li> |