linux-stable.git/drivers/tty/hvc, branch v6.8

tty: hvc: Don't enable the RISC-V SBI console by default

2024-02-19T08:43:33+00:00

The new SBI console has the same problem as the old one: there's only
one shared backing hardware and no synchronization, so the two drivers
end up stepping on each other.  This was the same issue the old SBI-0.1
console drivers had, but that was disabled by default when SBI-0.1 was.

So just mark the new driver as nonportable.

Reported-by: Emil Renner Berthing 
Fixes: 88ead68e764c ("tty: Add SBI debug console support to HVC SBI driver")
Signed-off-by: Palmer Dabbelt 
Reviewed-by: Paul Walmsley 
Reviewed-by: Anup Patel 
Reviewed-by: Conor Dooley 
Link: https://lore.kernel.org/r/20240214153429.16484-2-palmer@rivosinc.com
Signed-off-by: Greg Kroah-Hartman

Merge tag 'riscv-for-linus-6.8-mw4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2024-01-20T19:06:04+00:00

Pull more RISC-V updates from Palmer Dabbelt:

 - Support for tuning for systems with fast misaligned accesses.

 - Support for SBI-based suspend.

 - Support for the new SBI debug console extension.

 - The T-Head CMOs now use PA-based flushes.

 - Support for enabling the V extension in kernel code.

 - Optimized IP checksum routines.

 - Various ftrace improvements.

 - Support for archrandom, which depends on the Zkr extension.

 - The build is no longer broken under NET=n, KUNIT=y for ports that
   don't define their own ipv6 checksum.

* tag 'riscv-for-linus-6.8-mw4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (56 commits)
  lib: checksum: Fix build with CONFIG_NET=n
  riscv: lib: Check if output in asm goto supported
  riscv: Fix build error on rv32 + XIP
  riscv: optimize ELF relocation function in riscv
  RISC-V: Implement archrandom when Zkr is available
  riscv: Optimize hweight API with Zbb extension
  riscv: add dependency among Image(.gz), loader(.bin), and vmlinuz.efi
  samples: ftrace: Add RISC-V support for SAMPLE_FTRACE_DIRECT[_MULTI]
  riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support
  riscv: ftrace: Make function graph use ftrace directly
  riscv: select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
  lib/Kconfig.debug: Update AS_HAS_NON_CONST_LEB128 comment and name
  riscv: Restrict DWARF5 when building with LLVM to known working versions
  riscv: Hoist linker relaxation disabling logic into Kconfig
  kunit: Add tests for csum_ipv6_magic and ip_fast_csum
  riscv: Add checksum library
  riscv: Add checksum header
  riscv: Add static key for misaligned accesses
  asm-generic: Improve csum_fold
  RISC-V: selftests: cbo: Ensure asm operands match constraints
  ...

tty: Add SBI debug console support to HVC SBI driver

2024-01-10T15:04:05+00:00

RISC-V SBI specification supports advanced debug console
support via SBI DBCN extension.

Extend the HVC SBI driver to support it.

Signed-off-by: Atish Patra 
Signed-off-by: Anup Patel 
Reviewed-by: Andrew Jones 
Acked-by: Greg Kroah-Hartman 
Link: https://lore.kernel.org/r/20231124070905.1043092-5-apatel@ventanamicro.com
Signed-off-by: Palmer Dabbelt

tty: hvc: convert to u8 and size_t

2023-12-08T11:02:37+00:00

Switch character types to u8 and sizes to size_t. To conform to
characters/sizes in the rest of the tty layer.

Signed-off-by: "Jiri Slaby (SUSE)" 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Christophe Leroy 
Cc: Amit Shah 
Cc: Arnd Bergmann 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux.dev
Cc: linux-riscv@lists.infradead.org
Link: https://lore.kernel.org/r/20231206073712.17776-13-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: hvc: dcc: Check for TXfull condition while setting up early console

2023-12-08T11:02:37+00:00

Refer ARM DDI 0487I.a ID081822, D17.3.8, DBGDTRTX_EL0,
"If TXfull is set to 1, set DTRRX and DTRTX to UNKNOWN"

Thus one should always check for TXfull condition before hvc can be
used as an early console. This is similar to what is being done
today in hvc_dcc_console_init() and hvc_dcc_init().

The count 0x4000000 has been obtained from uboot (v2024.01-rc3)
drivers/serial/arm_dcc.c "TIMEOUT_COUNT".
It reads the dcc status and waits for 0x4000000  times for the TX Fifo
to be available before returning an error. Thus, it will prevent DCC
to be used as early console.

Signed-off-by: Ayan Kumar Halder 
Link: https://lore.kernel.org/r/20231205123534.3376883-1-ayan.kumar.halder@amd.com
Signed-off-by: Greg Kroah-Hartman

tty: hvc_console: use flexible array for outbuf

2023-11-25T07:23:17+00:00

This means:
* move outbuf to the end of struct hvc_struct and convert from pointer
  to flexible array (the structure is smaller now)
* use struct_size() at the allocation site
* align outbuf in the struct instead of ALIGN() at kzalloc()

And apart from the above, use u8 instead of char (which are the same
thanks to -funsigned-char). The former is now preferred over the latter.

It makes the code easier to understand.

Signed-off-by: "Jiri Slaby (SUSE)" 
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20231121092258.9334-12-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: hvc: hvc_opal: Convert to platform remove callback returning void

2023-11-23T19:31:08+00:00

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König 
Reviewed-by: Nicholas Piggin 
Link: https://lore.kernel.org/r/20231105214406.3765906-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman

tty: hvc: Make hvc_remove() return no value

2023-11-23T19:31:08+00:00

The function hvc_remove() returns zero unconditionally. Make it return
void instead to make it obvious that the caller doesn't need to do any
error handling. Accordingly drop the error handling from
hvc_opal_remove().

Signed-off-by: Uwe Kleine-König 
Reviewed-by: Nicholas Piggin 
Link: https://lore.kernel.org/r/20231105214406.3765906-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman

Merge tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2023-11-04T01:44:25+00:00

Pull tty and serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.7-rc1. Included
  in here are:

   - console/vgacon cleanups and removals from Arnd

   - tty core and n_tty cleanups from Jiri

   - lots of 8250 driver updates and cleanups

   - sc16is7xx serial driver updates

   - dt binding updates

   - first set of port lock wrapers from Thomas for the printk fixes
     coming in future releases

   - other small serial and tty core cleanups and updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (193 commits)
  serdev: Replace custom code with device_match_acpi_handle()
  serdev: Simplify devm_serdev_device_open() function
  serdev: Make use of device_set_node()
  tty: n_gsm: add copyright Siemens Mobility GmbH
  tty: n_gsm: fix race condition in status line change on dead connections
  serial: core: Fix runtime PM handling for pending tx
  vgacon: fix mips/sibyte build regression
  dt-bindings: serial: drop unsupported samsung bindings
  tty: serial: samsung: drop earlycon support for unsupported platforms
  tty: 8250: Add note for PX-835
  tty: 8250: Fix IS-200 PCI ID comment
  tty: 8250: Add Brainboxes Oxford Semiconductor-based quirks
  tty: 8250: Add support for Intashield IX cards
  tty: 8250: Add support for additional Brainboxes PX cards
  tty: 8250: Fix up PX-803/PX-857
  tty: 8250: Fix port count of PX-257
  tty: 8250: Add support for Intashield IS-100
  tty: 8250: Add support for Brainboxes UP cards
  tty: 8250: Add support for additional Brainboxes UC cards
  tty: 8250: Remove UC-257 and UC-431
  ...

hvc/xen: fix console unplug

2023-10-21T16:33:02+00:00

On unplug of a Xen console, xencons_disconnect_backend() unconditionally
calls free_irq() via unbind_from_irqhandler(), causing a warning of
freeing an already-free IRQ:

(qemu) device_del con1
[   32.050919] ------------[ cut here ]------------
[   32.050942] Trying to free already-free IRQ 33
[   32.050990] WARNING: CPU: 0 PID: 51 at kernel/irq/manage.c:1895 __free_irq+0x1d4/0x330

It should be using evtchn_put() to tear down the event channel binding,
and let the Linux IRQ side of it be handled by notifier_del_irq() through
the HVC code.

On which topic... xencons_disconnect_backend() should call hvc_remove()
*first*, rather than tearing down the event channel and grant mapping
while they are in use. And then the IRQ is guaranteed to be freed by
the time it's torn down by evtchn_put().

Since evtchn_put() also closes the actual event channel, avoid calling
xenbus_free_evtchn() except in the failure path where the IRQ was not
successfully set up.

However, calling hvc_remove() at the start of xencons_disconnect_backend()
still isn't early enough. An unplug request is indicated by the backend
setting its state to XenbusStateClosing, which triggers a notification
to xencons_backend_changed(), which... does nothing except set its own
frontend state directly to XenbusStateClosed without *actually* tearing
down the HVC device or, you know, making sure it isn't actively in use.

So the backend sees the guest frontend set its state to XenbusStateClosed
and stops servicing the interrupt... and the guest spins for ever in the
domU_write_console() function waiting for the ring to drain.

Fix that one by calling hvc_remove() from xencons_backend_changed() before
signalling to the backend that it's OK to proceed with the removal.

Tested with 'dd if=/dev/zero of=/dev/hvc1' while telling Qemu to remove
the console device.

Signed-off-by: David Woodhouse 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231020161529.355083-4-dwmw2@infradead.org
Signed-off-by: Greg Kroah-Hartman