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Add functions to access the maximum size we can read/write using
regmap_raw_read/write().
This helps drivers that need to know how much they can write with the
raw functions without problems. There are some devices (e.g. bmc150)
that have fifos as registers which need to be read in specific chunks
otherwise samples are dropped.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
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There are some buses which have a limit on the maximum number of bytes
that can be send/received. An example for this is
I2C_FUNC_SMBUS_I2C_BLOCK which does not support any reads/writes of more
than 32 bytes. The regmap_bulk operations should still be able to
utilize the full 32 bytes in this case.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
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Some use of those functions were providing unitialized values to those
functions. Notably, when reading 0 bytes from an empty file on a 9P
filesystem, the return code of read() was not 0.
Tested with this simple program:
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
int main(int argc, const char **argv)
{
assert(argc == 2);
char buffer[256];
int fd = open(argv[1], O_RDONLY|O_NOCTTY);
assert(fd >= 0);
assert(read(fd, buffer, 0) == 0);
return 0;
}
Cc: stable@vger.kernel.org # v4.1
Signed-off-by: Vincent Bernat <vincent@bernat.im>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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During later stages of math-emu bootup the following crash triggers:
math_emulate: 0060:c100d0a8
Kernel panic - not syncing: Math emulation needed in kernel
CPU: 0 PID: 1511 Comm: login Not tainted 4.2.0-rc7+ #1012
[...]
Call Trace:
[<c181d50d>] dump_stack+0x41/0x52
[<c181c918>] panic+0x77/0x189
[<c1003530>] ? math_error+0x140/0x140
[<c164c2d7>] math_emulate+0xba7/0xbd0
[<c100d0a8>] ? fpu__copy+0x138/0x1c0
[<c1109c3c>] ? __alloc_pages_nodemask+0x12c/0x870
[<c136ac20>] ? proc_clear_tty+0x40/0x70
[<c136ac6e>] ? session_clear_tty+0x1e/0x30
[<c1003530>] ? math_error+0x140/0x140
[<c1003575>] do_device_not_available+0x45/0x70
[<c100d0a8>] ? fpu__copy+0x138/0x1c0
[<c18258e6>] error_code+0x5a/0x60
[<c1003530>] ? math_error+0x140/0x140
[<c100d0a8>] ? fpu__copy+0x138/0x1c0
[<c100c205>] arch_dup_task_struct+0x25/0x30
[<c1048cea>] copy_process.part.51+0xea/0x1480
[<c115a8e5>] ? dput+0x175/0x200
[<c136af70>] ? no_tty+0x30/0x30
[<c1157242>] ? do_vfs_ioctl+0x322/0x540
[<c104a21a>] _do_fork+0xca/0x340
[<c1057b06>] ? SyS_rt_sigaction+0x66/0x90
[<c104a557>] SyS_clone+0x27/0x30
[<c1824a80>] sysenter_do_call+0x12/0x12
The reason is the incorrect assumption in fpu_copy(), that FNSAVE
can be executed from math-emu kernels as well.
Don't try to copy the registers, the soft state will be copied
by fork anyway, so the child task inherits the parent task's
soft math state.
With this fix applied math-emu kernels boot up fine on modern
hardware and the 'no387 nofxsr' boot options.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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On a math-emu bootup the following crash occurs:
Initializing CPU#0
------------[ cut here ]------------
kernel BUG at arch/x86/kernel/traps.c:779!
invalid opcode: 0000 [#1] SMP
[...]
EIP is at do_device_not_available+0xe/0x70
[...]
Call Trace:
[<c18238e6>] error_code+0x5a/0x60
[<c1002bd0>] ? math_error+0x140/0x140
[<c100bbd9>] ? fpu__init_cpu+0x59/0xa0
[<c1012322>] cpu_init+0x202/0x330
[<c104509f>] ? __native_set_fixmap+0x1f/0x30
[<c1b56ab0>] trap_init+0x305/0x346
[<c1b548af>] start_kernel+0x1a5/0x35d
[<c1b542b4>] i386_start_kernel+0x82/0x86
The reason is that in the following commit:
b1276c48e91b ("x86/fpu: Initialize fpregs in fpu__init_cpu_generic()")
I failed to consider math-emu's limitation that it cannot execute the
FNINIT instruction in kernel mode.
The long term fix might be to allow math-emu to execute (certain) kernel
mode FPU instructions, but for now apply the safe (albeit somewhat ugly)
fix: initialize the emulation state explicitly without trapping out to
the FPU emulator.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Markus Pargmann
Linus Torvalds
Vincent Bernat
Ingo Molnar