From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- Documentation/arch/sh/booting.rst | 12 ++ Documentation/arch/sh/features.rst | 3 + Documentation/arch/sh/index.rst | 50 ++++++ Documentation/arch/sh/new-machine.rst | 277 +++++++++++++++++++++++++++++++ Documentation/arch/sh/register-banks.rst | 40 +++++ 5 files changed, 382 insertions(+) create mode 100644 Documentation/arch/sh/booting.rst create mode 100644 Documentation/arch/sh/features.rst create mode 100644 Documentation/arch/sh/index.rst create mode 100644 Documentation/arch/sh/new-machine.rst create mode 100644 Documentation/arch/sh/register-banks.rst (limited to 'Documentation/arch/sh') diff --git a/Documentation/arch/sh/booting.rst b/Documentation/arch/sh/booting.rst new file mode 100644 index 000000000..d851c49a0 --- /dev/null +++ b/Documentation/arch/sh/booting.rst @@ -0,0 +1,12 @@ +.. SPDX-License-Identifier: GPL-2.0 + +DeviceTree Booting +------------------ + + Device-tree compatible SH bootloaders are expected to provide the physical + address of the device tree blob in r4. Since legacy bootloaders did not + guarantee any particular initial register state, kernels built to + inter-operate with old bootloaders must either use a builtin DTB or + select a legacy board option (something other than CONFIG_SH_DEVICE_TREE) + that does not use device tree. Support for the latter is being phased out + in favor of device tree. diff --git a/Documentation/arch/sh/features.rst b/Documentation/arch/sh/features.rst new file mode 100644 index 000000000..fae48fe81 --- /dev/null +++ b/Documentation/arch/sh/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features sh diff --git a/Documentation/arch/sh/index.rst b/Documentation/arch/sh/index.rst new file mode 100644 index 000000000..01fce7c13 --- /dev/null +++ b/Documentation/arch/sh/index.rst @@ -0,0 +1,50 @@ +======================= +SuperH Interfaces Guide +======================= + +:Author: Paul Mundt + +.. toctree:: + :maxdepth: 1 + + booting + new-machine + register-banks + + features + +Memory Management +================= + +SH-4 +---- + +Store Queue API +~~~~~~~~~~~~~~~ + +.. kernel-doc:: arch/sh/kernel/cpu/sh4/sq.c + :export: + +Machine Specific Interfaces +=========================== + +mach-dreamcast +-------------- + +.. kernel-doc:: arch/sh/boards/mach-dreamcast/rtc.c + :internal: + +mach-x3proto +------------ + +.. kernel-doc:: arch/sh/boards/mach-x3proto/ilsel.c + :export: + +Busses +====== + +Maple +----- + +.. kernel-doc:: drivers/sh/maple/maple.c + :export: diff --git a/Documentation/arch/sh/new-machine.rst b/Documentation/arch/sh/new-machine.rst new file mode 100644 index 000000000..e501c52b3 --- /dev/null +++ b/Documentation/arch/sh/new-machine.rst @@ -0,0 +1,277 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================= +Adding a new board to LinuxSH +============================= + + Paul Mundt + +This document attempts to outline what steps are necessary to add support +for new boards to the LinuxSH port under the new 2.5 and 2.6 kernels. This +also attempts to outline some of the noticeable changes between the 2.4 +and the 2.5/2.6 SH backend. + +1. New Directory Structure +========================== + +The first thing to note is the new directory structure. Under 2.4, most +of the board-specific code (with the exception of stboards) ended up +in arch/sh/kernel/ directly, with board-specific headers ending up in +include/asm-sh/. For the new kernel, things are broken out by board type, +companion chip type, and CPU type. Looking at a tree view of this directory +hierarchy looks like the following: + +Board-specific code:: + + . + |-- arch + | `-- sh + | `-- boards + | |-- adx + | | `-- board-specific files + | |-- bigsur + | | `-- board-specific files + | | + | ... more boards here ... + | + `-- include + `-- asm-sh + |-- adx + | `-- board-specific headers + |-- bigsur + | `-- board-specific headers + | + .. more boards here ... + +Next, for companion chips:: + + . + `-- arch + `-- sh + `-- cchips + `-- hd6446x + `-- hd64461 + `-- cchip-specific files + +... and so on. Headers for the companion chips are treated the same way as +board-specific headers. Thus, include/asm-sh/hd64461 is home to all of the +hd64461-specific headers. + +Finally, CPU family support is also abstracted:: + + . + |-- arch + | `-- sh + | |-- kernel + | | `-- cpu + | | |-- sh2 + | | | `-- SH-2 generic files + | | |-- sh3 + | | | `-- SH-3 generic files + | | `-- sh4 + | | `-- SH-4 generic files + | `-- mm + | `-- This is also broken out per CPU family, so each family can + | have their own set of cache/tlb functions. + | + `-- include + `-- asm-sh + |-- cpu-sh2 + | `-- SH-2 specific headers + |-- cpu-sh3 + | `-- SH-3 specific headers + `-- cpu-sh4 + `-- SH-4 specific headers + +It should be noted that CPU subtypes are _not_ abstracted. Thus, these still +need to be dealt with by the CPU family specific code. + +2. Adding a New Board +===================== + +The first thing to determine is whether the board you are adding will be +isolated, or whether it will be part of a family of boards that can mostly +share the same board-specific code with minor differences. + +In the first case, this is just a matter of making a directory for your +board in arch/sh/boards/ and adding rules to hook your board in with the +build system (more on this in the next section). However, for board families +it makes more sense to have a common top-level arch/sh/boards/ directory +and then populate that with sub-directories for each member of the family. +Both the Solution Engine and the hp6xx boards are an example of this. + +After you have setup your new arch/sh/boards/ directory, remember that you +should also add a directory in include/asm-sh for headers localized to this +board (if there are going to be more than one). In order to interoperate +seamlessly with the build system, it's best to have this directory the same +as the arch/sh/boards/ directory name, though if your board is again part of +a family, the build system has ways of dealing with this (via incdir-y +overloading), and you can feel free to name the directory after the family +member itself. + +There are a few things that each board is required to have, both in the +arch/sh/boards and the include/asm-sh/ hierarchy. In order to better +explain this, we use some examples for adding an imaginary board. For +setup code, we're required at the very least to provide definitions for +get_system_type() and platform_setup(). For our imaginary board, this +might look something like:: + + /* + * arch/sh/boards/vapor/setup.c - Setup code for imaginary board + */ + #include + + const char *get_system_type(void) + { + return "FooTech Vaporboard"; + } + + int __init platform_setup(void) + { + /* + * If our hardware actually existed, we would do real + * setup here. Though it's also sane to leave this empty + * if there's no real init work that has to be done for + * this board. + */ + + /* Start-up imaginary PCI ... */ + + /* And whatever else ... */ + + return 0; + } + +Our new imaginary board will also have to tie into the machvec in order for it +to be of any use. + +machvec functions fall into a number of categories: + + - I/O functions to IO memory (inb etc) and PCI/main memory (readb etc). + - I/O mapping functions (ioport_map, ioport_unmap, etc). + - a 'heartbeat' function. + - PCI and IRQ initialization routines. + - Consistent allocators (for boards that need special allocators, + particularly for allocating out of some board-specific SRAM for DMA + handles). + +There are machvec functions added and removed over time, so always be sure to +consult include/asm-sh/machvec.h for the current state of the machvec. + +The kernel will automatically wrap in generic routines for undefined function +pointers in the machvec at boot time, as machvec functions are referenced +unconditionally throughout most of the tree. Some boards have incredibly +sparse machvecs (such as the dreamcast and sh03), whereas others must define +virtually everything (rts7751r2d). + +Adding a new machine is relatively trivial (using vapor as an example): + +If the board-specific definitions are quite minimalistic, as is the case for +the vast majority of boards, simply having a single board-specific header is +sufficient. + + - add a new file include/asm-sh/vapor.h which contains prototypes for + any machine specific IO functions prefixed with the machine name, for + example vapor_inb. These will be needed when filling out the machine + vector. + + Note that these prototypes are generated automatically by setting + __IO_PREFIX to something sensible. A typical example would be:: + + #define __IO_PREFIX vapor + #include + + somewhere in the board-specific header. Any boards being ported that still + have a legacy io.h should remove it entirely and switch to the new model. + + - Add machine vector definitions to the board's setup.c. At a bare minimum, + this must be defined as something like:: + + struct sh_machine_vector mv_vapor __initmv = { + .mv_name = "vapor", + }; + ALIAS_MV(vapor) + + - finally add a file arch/sh/boards/vapor/io.c, which contains definitions of + the machine specific io functions (if there are enough to warrant it). + +3. Hooking into the Build System +================================ + +Now that we have the corresponding directories setup, and all of the +board-specific code is in place, it's time to look at how to get the +whole mess to fit into the build system. + +Large portions of the build system are now entirely dynamic, and merely +require the proper entry here and there in order to get things done. + +The first thing to do is to add an entry to arch/sh/Kconfig, under the +"System type" menu:: + + config SH_VAPOR + bool "Vapor" + help + select Vapor if configuring for a FooTech Vaporboard. + +next, this has to be added into arch/sh/Makefile. All boards require a +machdir-y entry in order to be built. This entry needs to be the name of +the board directory as it appears in arch/sh/boards, even if it is in a +sub-directory (in which case, all parent directories below arch/sh/boards/ +need to be listed). For our new board, this entry can look like:: + + machdir-$(CONFIG_SH_VAPOR) += vapor + +provided that we've placed everything in the arch/sh/boards/vapor/ directory. + +Next, the build system assumes that your include/asm-sh directory will also +be named the same. If this is not the case (as is the case with multiple +boards belonging to a common family), then the directory name needs to be +implicitly appended to incdir-y. The existing code manages this for the +Solution Engine and hp6xx boards, so see these for an example. + +Once that is taken care of, it's time to add an entry for the mach type. +This is done by adding an entry to the end of the arch/sh/tools/mach-types +list. The method for doing this is self explanatory, and so we won't waste +space restating it here. After this is done, you will be able to use +implicit checks for your board if you need this somewhere throughout the +common code, such as:: + + /* Make sure we're on the FooTech Vaporboard */ + if (!mach_is_vapor()) + return -ENODEV; + +also note that the mach_is_boardname() check will be implicitly forced to +lowercase, regardless of the fact that the mach-types entries are all +uppercase. You can read the script if you really care, but it's pretty ugly, +so you probably don't want to do that. + +Now all that's left to do is providing a defconfig for your new board. This +way, other people who end up with this board can simply use this config +for reference instead of trying to guess what settings are supposed to be +used on it. + +Also, as soon as you have copied over a sample .config for your new board +(assume arch/sh/configs/vapor_defconfig), you can also use this directly as a +build target, and it will be implicitly listed as such in the help text. + +Looking at the 'make help' output, you should now see something like: + +Architecture specific targets (sh): + + ======================= ============================================= + zImage Compressed kernel image (arch/sh/boot/zImage) + adx_defconfig Build for adx + cqreek_defconfig Build for cqreek + dreamcast_defconfig Build for dreamcast + ... + vapor_defconfig Build for vapor + ======================= ============================================= + +which then allows you to do:: + + $ make ARCH=sh CROSS_COMPILE=sh4-linux- vapor_defconfig vmlinux + +which will in turn copy the defconfig for this board, run it through +oldconfig (prompting you for any new options since the time of creation), +and start you on your way to having a functional kernel for your new +board. diff --git a/Documentation/arch/sh/register-banks.rst b/Documentation/arch/sh/register-banks.rst new file mode 100644 index 000000000..2bef5c8fc --- /dev/null +++ b/Documentation/arch/sh/register-banks.rst @@ -0,0 +1,40 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================== +Notes on register bank usage in the kernel +========================================== + +Introduction +------------ + +The SH-3 and SH-4 CPU families traditionally include a single partial register +bank (selected by SR.RB, only r0 ... r7 are banked), whereas other families +may have more full-featured banking or simply no such capabilities at all. + +SR.RB banking +------------- + +In the case of this type of banking, banked registers are mapped directly to +r0 ... r7 if SR.RB is set to the bank we are interested in, otherwise ldc/stc +can still be used to reference the banked registers (as r0_bank ... r7_bank) +when in the context of another bank. The developer must keep the SR.RB value +in mind when writing code that utilizes these banked registers, for obvious +reasons. Userspace is also not able to poke at the bank1 values, so these can +be used rather effectively as scratch registers by the kernel. + +Presently the kernel uses several of these registers. + + - r0_bank, r1_bank (referenced as k0 and k1, used for scratch + registers when doing exception handling). + + - r2_bank (used to track the EXPEVT/INTEVT code) + + - Used by do_IRQ() and friends for doing irq mapping based off + of the interrupt exception vector jump table offset + + - r6_bank (global interrupt mask) + + - The SR.IMASK interrupt handler makes use of this to set the + interrupt priority level (used by local_irq_enable()) + + - r7_bank (current) -- cgit v1.3.1