tjh.dev/kernel at 0d9e734018d70cecf79e2e4c6082167160a0f13f

Pull more random number generator updates from Jason Donenfeld:
"This time with some large scale treewide cleanups.

The intent of this pull is to clean up the way callers fetch random
integers. The current rules for doing this right are:

- If you want a secure or an insecure random u64, use get_random_u64()

- If you want a secure or an insecure random u32, use get_random_u32()

The old function prandom_u32() has been deprecated for a while
now and is just a wrapper around get_random_u32(). Same for
get_random_int().

- If you want a secure or an insecure random u16, use get_random_u16()

- If you want a secure or an insecure random u8, use get_random_u8()

- If you want secure or insecure random bytes, use get_random_bytes().

The old function prandom_bytes() has been deprecated for a while
now and has long been a wrapper around get_random_bytes()

- If you want a non-uniform random u32, u16, or u8 bounded by a
certain open interval maximum, use prandom_u32_max()

I say "non-uniform", because it doesn't do any rejection sampling
or divisions. Hence, it stays within the prandom_*() namespace, not
the get_random_*() namespace.

I'm currently investigating a "uniform" function for 6.2. We'll see
what comes of that.

By applying these rules uniformly, we get several benefits:

- By using prandom_u32_max() with an upper-bound that the compiler
can prove at compile-time is ≤65536 or ≤256, internally
get_random_u16() or get_random_u8() is used, which wastes fewer
batched random bytes, and hence has higher throughput.

- By using prandom_u32_max() instead of %, when the upper-bound is
not a constant, division is still avoided, because
prandom_u32_max() uses a faster multiplication-based trick instead.

- By using get_random_u16() or get_random_u8() in cases where the
return value is intended to indeed be a u16 or a u8, we waste fewer
batched random bytes, and hence have higher throughput.

This series was originally done by hand while I was on an airplane
without Internet. Later, Kees and I worked on retroactively figuring
out what could be done with Coccinelle and what had to be done
manually, and then we split things up based on that.

So while this touches a lot of files, the actual amount of code that's
hand fiddled is comfortably small"

* tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
prandom: remove unused functions
treewide: use get_random_bytes() when possible
treewide: use get_random_u32() when possible
treewide: use get_random_{u8,u16}() when possible, part 2
treewide: use get_random_{u8,u16}() when possible, part 1
treewide: use prandom_u32_max() when possible, part 2
treewide: use prandom_u32_max() when possible, part 1

f1947d7c

Linus Torvalds

3 years ago

Merge tag 'perf-tools-for-v6.1-2-2022-10-16' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull more perf tools updates from Arnaldo Carvalho de Melo:

- Use BPF CO-RE (Compile Once, Run Everywhere) to support old kernels
when using bperf (perf BPF based counters) with cgroups.

- Support HiSilicon PCIe Performance Monitoring Unit (PMU), that
monitors bandwidth, latency, bus utilization and buffer occupancy.

Documented in Documentation/admin-guide/perf/hisi-pcie-pmu.rst.

- User space tasks can migrate between CPUs, so when tracing selected
CPUs, system-wide sideband is still needed, fix it in the setup of
Intel PT on hybrid systems.

- Fix metricgroups title message in 'perf list', it should state that
the metrics groups are to be used with the '-M' option, not '-e'.

- Sync the msr-index.h copy with the kernel sources, adding support for
using "AMD64_TSC_RATIO" in filter expressions in 'perf trace' as well
as decoding it when printing the MSR tracepoint arguments.

- Fix program header size and alignment when generating a JIT ELF in
'perf inject'.

- Add multiple new Intel PT 'perf test' entries, including a jitdump
one.

- Fix the 'perf test' entries for 'perf stat' CSV and JSON output when
running on PowerPC due to an invalid topology number in that arch.

- Fix the 'perf test' for arm_coresight failures on the ARM Juno
system.

- Fix the 'perf test' attr entry for PERF_FORMAT_LOST, adding this
option to the or expression expected in the intercepted
perf_event_open() syscall.

- Add missing condition flags ('hs', 'lo', 'vc', 'vs') for arm64 in the
'perf annotate' asm parser.

- Fix 'perf mem record -C' option processing, it was being chopped up
when preparing the underlying 'perf record -e mem-events' and thus
being ignored, requiring using '-- -C CPUs' as a workaround.

- Improvements and tidy ups for 'perf test' shell infra.

- Fix Intel PT information printing segfault in uClibc, where a NULL
format was being passed to fprintf.

* tag 'perf-tools-for-v6.1-2-2022-10-16' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (23 commits)
tools arch x86: Sync the msr-index.h copy with the kernel sources
perf auxtrace arm64: Add support for parsing HiSilicon PCIe Trace packet
perf auxtrace arm64: Add support for HiSilicon PCIe Tune and Trace device driver
perf auxtrace arm: Refactor event list iteration in auxtrace_record__init()
perf tests stat+json_output: Include sanity check for topology
perf tests stat+csv_output: Include sanity check for topology
perf intel-pt: Fix system_wide dummy event for hybrid
perf intel-pt: Fix segfault in intel_pt_print_info() with uClibc
perf test: Fix attr tests for PERF_FORMAT_LOST
perf test: test_intel_pt.sh: Add 9 tests
perf inject: Fix GEN_ELF_TEXT_OFFSET for jit
perf test: test_intel_pt.sh: Add jitdump test
perf test: test_intel_pt.sh: Tidy some alignment
perf test: test_intel_pt.sh: Print a message when skipping kernel tracing
perf test: test_intel_pt.sh: Tidy some perf record options
perf test: test_intel_pt.sh: Fix return checking again
perf: Skip and warn on unknown format 'configN' attrs
perf list: Fix metricgroups title message
perf mem: Fix -C option behavior for perf mem record
perf annotate: Add missing condition flags for arm64
...

8636df94

Linus Torvalds

3 years ago

prandom: remove unused functions

de492c83

Jason A. Donenfeld

3 years ago

Merge tag 'kbuild-fixes-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2df76606

Linus Torvalds

3 years ago

tools arch x86: Sync the msr-index.h copy with the kernel sources

To pick up the changes in:

b8d1d163604bd1e6 ("x86/apic: Don't disable x2APIC if locked")
ca5b7c0d9621702e ("perf/x86/amd/lbr: Add LbrExtV2 branch record support")

Addressing these tools/perf build warnings:

diff -u tools/arch/x86/include/asm/msr-index.h arch/x86/include/asm/msr-index.h
Warning: Kernel ABI header at 'tools/arch/x86/include/asm/msr-index.h' differs from latest version at 'arch/x86/include/asm/msr-index.h'

That makes the beautification scripts to pick some new entries:

$ tools/perf/trace/beauty/tracepoints/x86_msr.sh > before
$ cp arch/x86/include/asm/msr-index.h tools/arch/x86/include/asm/msr-index.h
$ tools/perf/trace/beauty/tracepoints/x86_msr.sh > after
$ diff -u before after
--- before 2022-10-14 18:06:34.294561729 -0300
+++ after 2022-10-14 18:06:41.285744044 -0300
@@ -264,6 +264,7 @@
[0xc0000102 - x86_64_specific_MSRs_offset] = "KERNEL_GS_BASE",
[0xc0000103 - x86_64_specific_MSRs_offset] = "TSC_AUX",
[0xc0000104 - x86_64_specific_MSRs_offset] = "AMD64_TSC_RATIO",
+ [0xc000010e - x86_64_specific_MSRs_offset] = "AMD64_LBR_SELECT",
[0xc000010f - x86_64_specific_MSRs_offset] = "AMD_DBG_EXTN_CFG",
[0xc0000300 - x86_64_specific_MSRs_offset] = "AMD64_PERF_CNTR_GLOBAL_STATUS",
[0xc0000301 - x86_64_specific_MSRs_offset] = "AMD64_PERF_CNTR_GLOBAL_CTL",
$

Now one can trace systemwide asking to see backtraces to where that MSR
is being read/written, see this example with a previous update:

# perf trace -e msr:*_msr/max-stack=32/ --filter="msr>=IA32_U_CET && msr<=IA32_INT_SSP_TAB"
^C#

If we use -v (verbose mode) we can see what it does behind the scenes:

# perf trace -v -e msr:*_msr/max-stack=32/ --filter="msr>=IA32_U_CET && msr<=IA32_INT_SSP_TAB"
Using CPUID AuthenticAMD-25-21-0
0x6a0
0x6a8
New filter for msr:read_msr: (msr>=0x6a0 && msr<=0x6a8) && (common_pid != 597499 && common_pid != 3313)
0x6a0
0x6a8
New filter for msr:write_msr: (msr>=0x6a0 && msr<=0x6a8) && (common_pid != 597499 && common_pid != 3313)
mmap size 528384B
^C#

Example with a frequent msr:

# perf trace -v -e msr:*_msr/max-stack=32/ --filter="msr==IA32_SPEC_CTRL" --max-events 2
Using CPUID AuthenticAMD-25-21-0
0x48
New filter for msr:read_msr: (msr==0x48) && (common_pid != 2612129 && common_pid != 3841)
0x48
New filter for msr:write_msr: (msr==0x48) && (common_pid != 2612129 && common_pid != 3841)
mmap size 528384B
Looking at the vmlinux_path (8 entries long)
symsrc__init: build id mismatch for vmlinux.
Using /proc/kcore for kernel data
Using /proc/kallsyms for symbols
0.000 Timer/2525383 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
do_trace_write_msr ([kernel.kallsyms])
do_trace_write_msr ([kernel.kallsyms])
__switch_to_xtra ([kernel.kallsyms])
__switch_to ([kernel.kallsyms])
__schedule ([kernel.kallsyms])
schedule ([kernel.kallsyms])
futex_wait_queue_me ([kernel.kallsyms])
futex_wait ([kernel.kallsyms])
do_futex ([kernel.kallsyms])
__x64_sys_futex ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
__futex_abstimed_wait_common64 (/usr/lib64/libpthread-2.33.so)
0.030 :0/0 msr:write_msr(msr: IA32_SPEC_CTRL, val: 2)
do_trace_write_msr ([kernel.kallsyms])
do_trace_write_msr ([kernel.kallsyms])
__switch_to_xtra ([kernel.kallsyms])
__switch_to ([kernel.kallsyms])
__schedule ([kernel.kallsyms])
schedule_idle ([kernel.kallsyms])
do_idle ([kernel.kallsyms])
cpu_startup_entry ([kernel.kallsyms])
secondary_startup_64_no_verify ([kernel.kallsyms])
#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Link: https://lore.kernel.org/lkml/Y0nQkz2TUJxwfXJd@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

a3a36565

Arnaldo Carvalho de Melo

3 years ago

treewide: use get_random_bytes() when possible

197173db

Jason A. Donenfeld

3 years ago

branches 3

master 16 hours ago default

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v7.1-rc1

1 day ago latest

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.

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