linux/drivers/tty/hvc, branch v5.3

docs: powerpc: convert docs to ReST and rename to *.rst

2019-07-17T09:57:51Z

Convert docs to ReST and add them to the arch-specific book. The conversion here was trivial, as almost every file there was already using an elegant format close to ReST standard. The changes were mostly to mark literal blocks and add a few missing section title identifiers. One note with regards to "--": on Sphinx, this can't be used to identify a list, as it will format it badly. This can be used, however, to identify a long hyphen - and "---" is an even longer one. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab Acked-by: Andrew Donnellan # cxl

powerpc/pseries/hvconsole: Fix stack overread via udbg

2019-06-14T05:35:53Z

While developing KASAN for 64-bit book3s, I hit the following stack over-read. It occurs because the hypercall to put characters onto the terminal takes 2 longs (128 bits/16 bytes) of characters at a time, and so hvc_put_chars() would unconditionally copy 16 bytes from the argument buffer, regardless of supplied length. However, udbg_hvc_putc() can call hvc_put_chars() with a single-byte buffer, leading to the error. ================================================================== BUG: KASAN: stack-out-of-bounds in hvc_put_chars+0xdc/0x110 Read of size 8 at addr c0000000023e7a90 by task swapper/0 CPU: 0 PID: 0 Comm: swapper Not tainted 5.2.0-rc2-next-20190528-02824-g048a6ab4835b #113 Call Trace: dump_stack+0x104/0x154 (unreliable) print_address_description+0xa0/0x30c __kasan_report+0x20c/0x224 kasan_report+0x18/0x30 __asan_report_load8_noabort+0x24/0x40 hvc_put_chars+0xdc/0x110 hvterm_raw_put_chars+0x9c/0x110 udbg_hvc_putc+0x154/0x200 udbg_write+0xf0/0x240 console_unlock+0x868/0xd30 register_console+0x970/0xe90 register_early_udbg_console+0xf8/0x114 setup_arch+0x108/0x790 start_kernel+0x104/0x784 start_here_common+0x1c/0x534 Memory state around the buggy address: c0000000023e7980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 c0000000023e7a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 >c0000000023e7a80: f1 f1 01 f2 f2 f2 00 00 00 00 00 00 00 00 00 00 ^ c0000000023e7b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 c0000000023e7b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== Document that a 16-byte buffer is requred, and provide it in udbg. Signed-off-by: Daniel Axtens Signed-off-by: Michael Ellerman

Merge tag 'riscv-for-linus-5.2-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux

2019-05-19T16:56:36Z

Pull RISC-V updates from Palmer Dabbelt: "This contains an assortment of RISC-V related patches that I'd like to target for the 5.2 merge window. Most of the patches are cleanups, but there are a handful of user-visible changes: - The nosmp and nr_cpus command-line arguments are now supported, which work like normal. - The SBI console no longer installs itself as a preferred console, we rely on standard mechanisms (/chosen, command-line, hueristics) instead. - sfence_remove_sfence_vma{,_asid} now pass their arguments along to the SBI call. - Modules now support BUG(). - A missing sfence.vma during boot has been added. This bug only manifests during boot. - The arch/riscv support for SiFive's L2 cache controller has been merged, which should un-block the EDAC framework work. I've only tested this on QEMU again, as I didn't have time to get things running on the Unleashed. The latest master from this morning merges in cleanly and passes the tests as well" * tag 'riscv-for-linus-5.2-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux: (31 commits) riscv: fix locking violation in page fault handler RISC-V: sifive_l2_cache: Add L2 cache controller driver for SiFive SoCs RISC-V: Add DT documentation for SiFive L2 Cache Controller RISC-V: Avoid using invalid intermediate translations riscv: Support BUG() in kernel module riscv: Add the support for c.ebreak check in is_valid_bugaddr() riscv: support trap-based WARN() riscv: fix sbi_remote_sfence_vma{,_asid}. riscv: move switch_mm to its own file riscv: move flush_icache_{all,mm} to cacheflush.c tty: Don't force RISCV SBI console as preferred console RISC-V: Access CSRs using CSR numbers RISC-V: Add interrupt related SCAUSE defines in asm/csr.h RISC-V: Use tabs to align macro values in asm/csr.h RISC-V: Fix minor checkpatch issues. RISC-V: Support nr_cpus command line option. RISC-V: Implement nosmp commandline option. RISC-V: Add RISC-V specific arch_match_cpu_phys_id riscv: vdso: drop unnecessary cc-ldoption riscv: call pm_power_off from machine_halt / machine_power_off ...

tty: Don't force RISCV SBI console as preferred console

2019-05-17T03:42:11Z

The Linux kernel will auto-disables all boot consoles whenever it gets a preferred real console. Currently on RISC-V systems, if we have a real console which is not RISCV SBI console then boot consoles (such as earlycon=sbi) are not auto-disabled when a real console (ttyS0 or ttySIF0) is available. This results in duplicate prints at boot-time after kernel starts using real console (i.e. ttyS0 or ttySIF0) if "earlycon=" kernel parameter was passed by bootloader. The reason for above issue is that RISCV SBI console always adds itself as preferred console which is causing other real consoles to be not used as preferred console. Ideally "console=" kernel parameter passed by bootloaders should be the one selecting a preferred real console. This patch fixes above issue by not forcing RISCV SBI console as preferred console. Fixes: afa6b1ccfad5 ("tty: New RISC-V SBI console driver") Cc: stable@vger.kernel.org Signed-off-by: Anup Patel Reviewed-by: Atish Patra Signed-off-by: Palmer Dabbelt

tty: remove redundant 'default n' from Kconfig-s

2019-04-16T13:21:33Z

'default n' is the default value for any bool or tristate Kconfig setting so there is no need to write it explicitly. Also since commit f467c5640c29 ("kconfig: only write '# CONFIG_FOO is not set' for visible symbols") the Kconfig behavior is the same regardless of 'default n' being present or not: ... One side effect of (and the main motivation for) this change is making the following two definitions behave exactly the same: config FOO bool config FOO bool default n With this change, neither of these will generate a '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied). That might make it clearer to people that a bare 'default n' is redundant. ... Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: Greg Kroah-Hartman

tty: add SPDX identifiers to Kconfig and Makefiles

2019-04-04T16:48:43Z

There were a few Kconfig and Makefiles under drivers/tty/ that were missing a SPDX identifier. Fix that up so that automated tools can properly classify all kernel source files. Cc: Jiri Slaby Cc: Jiri Kosina Cc: Rob Herring Acked-by: David Sterba Reviewed-by: Mukesh Ojha Signed-off-by: Greg Kroah-Hartman

tty: hvc_xen: Mark expected switch fall-through

2019-02-26T11:30:44Z

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. This patch fixes the following warning: drivers/tty/hvc/hvc_xen.c: In function ‘xencons_backend_changed’: drivers/tty/hvc/hvc_xen.c:493:6: warning: this statement may fall through [-Wimplicit-fallthrough=] if (dev->state == XenbusStateClosed) ^ drivers/tty/hvc/hvc_xen.c:496:2: note: here case XenbusStateClosing: ^~~~ Warning level 3 was used: -Wimplicit-fallthrough=3 Notice that, in this particular case, the code comment is modified in accordance with what GCC is expecting to find. This patch is part of the ongoing efforts to enable -Wimplicit-fallthrough Signed-off-by: Gustavo A. R. Silva Signed-off-by: Greg Kroah-Hartman

tty: Use of_node_name_{eq,prefix} for node name comparisons

2018-12-17T15:12:17Z

Convert string compares of DT node names to use of_node_name_eq helper instead. This removes direct access to the node name pointer. For hvc, the code can also be simplified by using of_stdout pointer instead of searching again for the stdout node. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-serial@vger.kernel.org Cc: sparclinux@vger.kernel.org Signed-off-by: Rob Herring Acked-by: Michael Ellerman Acked-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tty: hvc: hvc_write() fix break condition

2018-09-10T16:04:31Z

Commit 550ddadcc758 ("tty: hvc: hvc_write() may sleep") broke the termination condition in case the driver stops accepting characters. This can result in unnecessary polling of the busy driver. Restore it by testing the hvc_push return code. Tested-by: Matteo Croce Tested-by: Jason Gunthorpe Tested-by: Leon Romanovsky Signed-off-by: Nicholas Piggin Signed-off-by: Greg Kroah-Hartman

tty: hvc: hvc_poll() fix read loop batching

2018-09-10T16:04:31Z

Commit ec97eaad1383 ("tty: hvc: hvc_poll() break hv read loop") removes get_chars batching entirely, which slows down large console operations like paste -- virtio console "feels worse than a 9600 baud serial line," reports Matteo. This adds back batching in a more latency friendly way. If the caller can sleep then we try to fill the entire flip buffer, releasing the lock and scheduling between each iteration. If it can not sleep, then batches are limited to 128 bytes. Matteo confirms this fixes the performance problem. Latency testing the powerpc OPAL console with OpenBMC UART with a large paste shows about 0.25ms latency, which seems reasonable. 10ms latencies were typical for this case before the latency breaking work, so we still see most of the benefit. kopald-1204 0d.h. 5us : hvc_poll <-hvc_handle_interrupt kopald-1204 0d.h. 5us : __hvc_poll <-hvc_handle_interrupt kopald-1204 0d.h. 5us : _raw_spin_lock_irqsave <-__hvc_poll kopald-1204 0d.h. 5us : tty_port_tty_get <-__hvc_poll kopald-1204 0d.h. 6us : _raw_spin_lock_irqsave <-tty_port_tty_get kopald-1204 0d.h. 6us : _raw_spin_unlock_irqrestore <-tty_port_tty_get kopald-1204 0d.h. 6us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 7us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 7us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 36us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 36us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 36us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 65us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 65us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 66us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 94us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 95us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 95us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 124us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 124us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 125us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 154us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 154us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 154us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 183us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 184us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 184us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 213us : tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 213us : __tty_buffer_request_room <-__hvc_poll kopald-1204 0d.h. 213us+: opal_get_chars <-__hvc_poll kopald-1204 0d.h. 242us : _raw_spin_unlock_irqrestore <-__hvc_poll kopald-1204 0d.h. 242us : tty_flip_buffer_push <-__hvc_poll kopald-1204 0d.h. 243us : queue_work_on <-tty_flip_buffer_push kopald-1204 0d.h. 243us : tty_kref_put <-__hvc_poll kopald-1204 0d.h. 243us : hvc_kick <-hvc_handle_interrupt kopald-1204 0d.h. 243us : wake_up_process <-hvc_kick kopald-1204 0d.h. 244us : try_to_wake_up <-hvc_kick kopald-1204 0d.h. 244us : _raw_spin_lock_irqsave <-try_to_wake_up kopald-1204 0d.h. 244us : _raw_spin_unlock_irqrestore <-try_to_wake_up Reported-by: Matteo Croce Tested-by: Matteo Croce Tested-by: Jason Gunthorpe Tested-by: Leon Romanovsky Signed-off-by: Nicholas Piggin Signed-off-by: Greg Kroah-Hartman