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/thunderbolt/cap.c | 256 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 256 insertions(+) create mode 100644 drivers/thunderbolt/cap.c (limited to 'drivers/thunderbolt/cap.c') diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c new file mode 100644 index 000000000..4ab22d529 --- /dev/null +++ b/drivers/thunderbolt/cap.c @@ -0,0 +1,256 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Thunderbolt driver - capabilities lookup + * + * Copyright (c) 2014 Andreas Noever + * Copyright (C) 2018, Intel Corporation + */ + +#include +#include + +#include "tb.h" + +#define CAP_OFFSET_MAX 0xff +#define VSE_CAP_OFFSET_MAX 0xffff +#define TMU_ACCESS_EN BIT(20) + +static int tb_port_enable_tmu(struct tb_port *port, bool enable) +{ + struct tb_switch *sw = port->sw; + u32 value, offset; + int ret; + + /* + * Legacy devices need to have TMU access enabled before port + * space can be fully accessed. + */ + if (tb_switch_is_light_ridge(sw)) + offset = 0x26; + else if (tb_switch_is_eagle_ridge(sw)) + offset = 0x2a; + else + return 0; + + ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1); + if (ret) + return ret; + + if (enable) + value |= TMU_ACCESS_EN; + else + value &= ~TMU_ACCESS_EN; + + return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1); +} + +static void tb_port_dummy_read(struct tb_port *port) +{ + /* + * When reading from next capability pointer location in port + * config space the read data is not cleared on LR. To avoid + * reading stale data on next read perform one dummy read after + * port capabilities are walked. + */ + if (tb_switch_is_light_ridge(port->sw)) { + u32 dummy; + + tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1); + } +} + +/** + * tb_port_next_cap() - Return next capability in the linked list + * @port: Port to find the capability for + * @offset: Previous capability offset (%0 for start) + * + * Finds dword offset of the next capability in port config space + * capability list. When passed %0 in @offset parameter, first entry + * will be returned, if it exists. + * + * Return: + * * Double word offset of the first or next capability - On success. + * * %0 - If no next capability is found. + * * Negative errno - Another error occurred. + */ +int tb_port_next_cap(struct tb_port *port, unsigned int offset) +{ + struct tb_cap_any header; + int ret; + + if (!offset) + return port->config.first_cap_offset; + + ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1); + if (ret) + return ret; + + return header.basic.next; +} + +static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap) +{ + int offset = 0; + + do { + struct tb_cap_any header; + int ret; + + offset = tb_port_next_cap(port, offset); + if (offset < 0) + return offset; + + ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1); + if (ret) + return ret; + + if (header.basic.cap == cap) + return offset; + } while (offset > 0); + + return -ENOENT; +} + +/** + * tb_port_find_cap() - Find port capability + * @port: Port to find the capability for + * @cap: Capability to look + * + * Return: + * * Offset to the start of capability - On success. + * * %-ENOENT - If no such capability was found. + * * Negative errno - Another error occurred. + */ +int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap) +{ + int ret; + + ret = tb_port_enable_tmu(port, true); + if (ret) + return ret; + + ret = __tb_port_find_cap(port, cap); + + tb_port_dummy_read(port); + tb_port_enable_tmu(port, false); + + return ret; +} + +/** + * tb_switch_next_cap() - Return next capability in the linked list + * @sw: Switch to find the capability for + * @offset: Previous capability offset (%0 for start) + * + * Finds dword offset of the next capability in port config space + * capability list. When passed %0 in @offset parameter, first entry + * will be returned, if it exists. + * + * Return: + * * Double word offset of the first or next capability - On success. + * * %0 - If no next capability is found. + * * Negative errno - Another error occurred. + */ +int tb_switch_next_cap(struct tb_switch *sw, unsigned int offset) +{ + struct tb_cap_any header; + int ret; + + if (!offset) + return sw->config.first_cap_offset; + + ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2); + if (ret) + return ret; + + switch (header.basic.cap) { + case TB_SWITCH_CAP_TMU: + ret = header.basic.next; + break; + + case TB_SWITCH_CAP_VSE: + if (!header.extended_short.length) + ret = header.extended_long.next; + else + ret = header.extended_short.next; + break; + + default: + tb_sw_dbg(sw, "unknown capability %#x at %#x\n", + header.basic.cap, offset); + ret = -EINVAL; + break; + } + + return ret >= VSE_CAP_OFFSET_MAX ? 0 : ret; +} + +/** + * tb_switch_find_cap() - Find switch capability + * @sw: Switch to find the capability for + * @cap: Capability to look + * + * Return: + * * Offset to the start of capability - On success. + * * %-ENOENT - If no such capability was found. + * * Negative errno - Another error occurred. + */ +int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap) +{ + int offset = 0; + + do { + struct tb_cap_any header; + int ret; + + offset = tb_switch_next_cap(sw, offset); + if (offset < 0) + return offset; + + ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1); + if (ret) + return ret; + + if (header.basic.cap == cap) + return offset; + } while (offset); + + return -ENOENT; +} + +/** + * tb_switch_find_vse_cap() - Find switch vendor specific capability + * @sw: Switch to find the capability for + * @vsec: Vendor specific capability to look + * + * This function enumerates vendor specific capabilities (VSEC) of a + * switch and returns offset when capability matching @vsec is found. + * + * Return: + * * Offset of capability - On success. + * * %-ENOENT - If capability was not found. + * * Negative errno - Another error occurred. + */ +int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec) +{ + int offset = 0; + + do { + struct tb_cap_any header; + int ret; + + offset = tb_switch_next_cap(sw, offset); + if (offset < 0) + return offset; + + ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1); + if (ret) + return ret; + + if (header.extended_short.cap == TB_SWITCH_CAP_VSE && + header.extended_short.vsec_id == vsec) + return offset; + } while (offset); + + return -ENOENT; +} -- cgit v1.3.1