From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- drivers/accessibility/braille/Makefile | 2 + drivers/accessibility/braille/braille_console.c | 379 ++++++++++++++++++++++++ 2 files changed, 381 insertions(+) create mode 100644 drivers/accessibility/braille/Makefile create mode 100644 drivers/accessibility/braille/braille_console.c (limited to 'drivers/accessibility/braille') diff --git a/drivers/accessibility/braille/Makefile b/drivers/accessibility/braille/Makefile new file mode 100644 index 000000000..fa4b87338 --- /dev/null +++ b/drivers/accessibility/braille/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille_console.o diff --git a/drivers/accessibility/braille/braille_console.c b/drivers/accessibility/braille/braille_console.c new file mode 100644 index 000000000..06b43b678 --- /dev/null +++ b/drivers/accessibility/braille/braille_console.c @@ -0,0 +1,379 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Minimalistic braille device kernel support. + * + * By default, shows console messages on the braille device. + * Pressing Insert switches to VC browsing. + * + * Copyright (C) Samuel Thibault + */ + +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include +#include + +MODULE_AUTHOR("samuel.thibault@ens-lyon.org"); +MODULE_DESCRIPTION("braille device"); + +/* + * Braille device support part. + */ + +/* Emit various sounds */ +static bool sound; +module_param(sound, bool, 0); +MODULE_PARM_DESC(sound, "emit sounds"); + +static void beep(unsigned int freq) +{ + if (sound) + kd_mksound(freq, HZ/10); +} + +/* mini console */ +#define WIDTH 40 +#define BRAILLE_KEY KEY_INSERT +static u16 console_buf[WIDTH]; +static int console_cursor; + +/* mini view of VC */ +static int vc_x, vc_y, lastvc_x, lastvc_y; + +/* show console ? (or show VC) */ +static int console_show = 1; +/* pending newline ? */ +static int console_newline = 1; +static int lastVC = -1; + +static struct console *braille_co; + +/* Very VisioBraille-specific */ +static void braille_write(u16 *buf) +{ + static u16 lastwrite[WIDTH]; + unsigned char data[1 + 1 + 2*WIDTH + 2 + 1], csum = 0, *c; + u16 out; + int i; + + if (!braille_co) + return; + + if (!memcmp(lastwrite, buf, WIDTH * sizeof(*buf))) + return; + memcpy(lastwrite, buf, WIDTH * sizeof(*buf)); + +#define SOH 1 +#define STX 2 +#define ETX 2 +#define EOT 4 +#define ENQ 5 + data[0] = STX; + data[1] = '>'; + csum ^= '>'; + c = &data[2]; + for (i = 0; i < WIDTH; i++) { + out = buf[i]; + if (out >= 0x100) + out = '?'; + else if (out == 0x00) + out = ' '; + csum ^= out; + if (out <= 0x05) { + *c++ = SOH; + out |= 0x40; + } + *c++ = out; + } + + if (csum <= 0x05) { + *c++ = SOH; + csum |= 0x40; + } + *c++ = csum; + *c++ = ETX; + + braille_co->write(braille_co, data, c - data); +} + +/* Follow the VC cursor*/ +static void vc_follow_cursor(struct vc_data *vc) +{ + vc_x = vc->state.x - (vc->state.x % WIDTH); + vc_y = vc->state.y; + lastvc_x = vc->state.x; + lastvc_y = vc->state.y; +} + +/* Maybe the VC cursor moved, if so follow it */ +static void vc_maybe_cursor_moved(struct vc_data *vc) +{ + if (vc->state.x != lastvc_x || vc->state.y != lastvc_y) + vc_follow_cursor(vc); +} + +/* Show portion of VC at vc_x, vc_y */ +static void vc_refresh(struct vc_data *vc) +{ + u16 buf[WIDTH]; + int i; + + for (i = 0; i < WIDTH; i++) { + u16 glyph = screen_glyph(vc, + 2 * (vc_x + i) + vc_y * vc->vc_size_row); + buf[i] = inverse_translate(vc, glyph, true); + } + braille_write(buf); +} + +/* + * Link to keyboard + */ + +static int keyboard_notifier_call(struct notifier_block *blk, + unsigned long code, void *_param) +{ + struct keyboard_notifier_param *param = _param; + struct vc_data *vc = param->vc; + int ret = NOTIFY_OK; + + if (!param->down) + return ret; + + switch (code) { + case KBD_KEYCODE: + if (console_show) { + if (param->value == BRAILLE_KEY) { + console_show = 0; + beep(880); + vc_maybe_cursor_moved(vc); + vc_refresh(vc); + ret = NOTIFY_STOP; + } + } else { + ret = NOTIFY_STOP; + switch (param->value) { + case KEY_INSERT: + beep(440); + console_show = 1; + lastVC = -1; + braille_write(console_buf); + break; + case KEY_LEFT: + if (vc_x > 0) { + vc_x -= WIDTH; + if (vc_x < 0) + vc_x = 0; + } else if (vc_y >= 1) { + beep(880); + vc_y--; + vc_x = vc->vc_cols-WIDTH; + } else + beep(220); + break; + case KEY_RIGHT: + if (vc_x + WIDTH < vc->vc_cols) { + vc_x += WIDTH; + } else if (vc_y + 1 < vc->vc_rows) { + beep(880); + vc_y++; + vc_x = 0; + } else + beep(220); + break; + case KEY_DOWN: + if (vc_y + 1 < vc->vc_rows) + vc_y++; + else + beep(220); + break; + case KEY_UP: + if (vc_y >= 1) + vc_y--; + else + beep(220); + break; + case KEY_HOME: + vc_follow_cursor(vc); + break; + case KEY_PAGEUP: + vc_x = 0; + vc_y = 0; + break; + case KEY_PAGEDOWN: + vc_x = 0; + vc_y = vc->vc_rows-1; + break; + default: + ret = NOTIFY_OK; + break; + } + if (ret == NOTIFY_STOP) + vc_refresh(vc); + } + break; + case KBD_POST_KEYSYM: + { + unsigned char type = KTYP(param->value) - 0xf0; + + if (type == KT_SPEC) { + unsigned char val = KVAL(param->value); + int on_off = -1; + + switch (val) { + case KVAL(K_CAPS): + on_off = vt_get_leds(fg_console, VC_CAPSLOCK); + break; + case KVAL(K_NUM): + on_off = vt_get_leds(fg_console, VC_NUMLOCK); + break; + case KVAL(K_HOLD): + on_off = vt_get_leds(fg_console, VC_SCROLLOCK); + break; + } + if (on_off == 1) + beep(880); + else if (on_off == 0) + beep(440); + } + } + break; + case KBD_UNBOUND_KEYCODE: + case KBD_UNICODE: + case KBD_KEYSYM: + /* Unused */ + break; + } + return ret; +} + +static struct notifier_block keyboard_notifier_block = { + .notifier_call = keyboard_notifier_call, +}; + +static int vt_notifier_call(struct notifier_block *blk, + unsigned long code, void *_param) +{ + struct vt_notifier_param *param = _param; + struct vc_data *vc = param->vc; + + switch (code) { + case VT_ALLOCATE: + break; + case VT_DEALLOCATE: + break; + case VT_WRITE: + { + unsigned char c = param->c; + + if (vc->vc_num != fg_console) + break; + switch (c) { + case '\b': + case 127: + if (console_cursor > 0) { + console_cursor--; + console_buf[console_cursor] = ' '; + } + break; + case '\n': + case '\v': + case '\f': + case '\r': + console_newline = 1; + break; + case '\t': + c = ' '; + fallthrough; + default: + if (c < 32) + /* Ignore other control sequences */ + break; + if (console_newline) { + memset(console_buf, 0, sizeof(console_buf)); + console_cursor = 0; + console_newline = 0; + } + if (console_cursor == WIDTH) + memmove(console_buf, &console_buf[1], + (WIDTH-1) * sizeof(*console_buf)); + else + console_cursor++; + console_buf[console_cursor-1] = c; + break; + } + if (console_show) + braille_write(console_buf); + else { + vc_maybe_cursor_moved(vc); + vc_refresh(vc); + } + break; + } + case VT_UPDATE: + /* Maybe a VT switch, flush */ + if (console_show) { + if (vc->vc_num != lastVC) { + lastVC = vc->vc_num; + memset(console_buf, 0, sizeof(console_buf)); + console_cursor = 0; + braille_write(console_buf); + } + } else { + vc_maybe_cursor_moved(vc); + vc_refresh(vc); + } + break; + } + return NOTIFY_OK; +} + +static struct notifier_block vt_notifier_block = { + .notifier_call = vt_notifier_call, +}; + +/* + * Called from printk.c when console=brl is given + */ + +int braille_register_console(struct console *console, int index, + char *console_options, char *braille_options) +{ + int ret; + + if (!console_options) + /* Only support VisioBraille for now */ + console_options = "57600o8"; + if (braille_co) + return -ENODEV; + if (console->setup) { + ret = console->setup(console, console_options); + if (ret != 0) + return ret; + } + console->flags |= CON_ENABLED; + console->index = index; + braille_co = console; + register_keyboard_notifier(&keyboard_notifier_block); + register_vt_notifier(&vt_notifier_block); + return 1; +} + +int braille_unregister_console(struct console *console) +{ + if (braille_co != console) + return -EINVAL; + unregister_keyboard_notifier(&keyboard_notifier_block); + unregister_vt_notifier(&vt_notifier_block); + braille_co = NULL; + return 1; +} -- cgit v1.3.1