abseil-cpp: backport RISC-V fix

Backport upstream fix[1] for SIGILL crash on RISC-V with 6.6 and
newer kernels.  The patch has been tweaked to apply on top of the
existing stack.

[1]: https://github.com/abseil/abseil-cpp/commit/7335a36d

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-oe/recipes-devtools/abseil-cpp/abseil-cpp/0004-PR-1644-unscaledcycleclock-remove-RISC-V-support.patch

@@ -0,0 +1,82 @@
+From 7335a36d0b5c1c597566f9aa3f458a5b6817c3b4 Mon Sep 17 00:00:00 2001
+From: aurel32 <aurelien@aurel32.net>
+Date: Fri, 22 Mar 2024 14:21:13 -0700
+Subject: [PATCH] PR #1644: unscaledcycleclock: remove RISC-V support
+
+Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1644
+
+Starting with Linux 6.6 [1], RDCYCLE is a privileged instruction on RISC-V and can't be used directly from userland. There is a sysctl option to change that as a transition period, but it will eventually disappear.
+
+The RDTIME instruction is another less accurate alternative, however its frequency varies from board to board, and there is currently now way to get its frequency from userland [2].
+
+Therefore this patch just removes the code for unscaledcycleclock on RISC-V. Without processor specific implementation, abseil relies on std::chrono::steady_clock::now().time_since_epoch() which is basically a wrapper around clock_gettime (CLOCK_MONOTONIC), which in turns use __vdso_clock_gettime(). On RISC-V this VDSO is just a wrapper around RDTIME correctly scaled to use nanoseconds units.
+
+This fixes the testsuite on riscv64, tested on a VisionFive 2 board.
+
+[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cc4c07c89aada16229084eeb93895c95b7eabaa3
+[2] https://github.com/abseil/abseil-cpp/pull/1631
+Merge 43356a2548cfde76e164d446cb69004b488c6a71 into 76f8011beabdaee872b5fde7546e02407b220cb1
+
+Merging this change closes #1644
+
+COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1644 from aurel32:rv64-no-unscaledcycleclock 43356a2548cfde76e164d446cb69004b488c6a71
+PiperOrigin-RevId: 618286262
+Change-Id: Ie4120a727e7d0bb185df6e06ea145c780ebe6652
+
+Upstream-Status: Backport [https://github.com/abseil/abseil-cpp/commit/7335a36d]
+[Adapted to apply on top of meta-oe's patch stack]
+Signed-off-by: Scott Murray <scott.murray@konsulko.com>
+---
+ absl/base/internal/unscaledcycleclock.cc       | 12 ------------
+ absl/base/internal/unscaledcycleclock_config.h |  5 ++---
+ 2 files changed, 2 insertions(+), 15 deletions(-)
+
+diff --git a/absl/base/internal/unscaledcycleclock.cc b/absl/base/internal/unscaledcycleclock.cc
+index f11fecb3..103b4f6a 100644
+--- a/absl/base/internal/unscaledcycleclock.cc
++++ b/absl/base/internal/unscaledcycleclock.cc
+@@ -121,18 +121,6 @@ double UnscaledCycleClock::Frequency() {
+   return aarch64_timer_frequency;
+ }
+ 
+-#elif defined(__riscv)
+-
+-int64_t UnscaledCycleClock::Now() {
+-  int64_t virtual_timer_value;
+-  asm volatile("rdcycle %0" : "=r"(virtual_timer_value));
+-  return virtual_timer_value;
+-}
+-
+-double UnscaledCycleClock::Frequency() {
+-  return base_internal::NominalCPUFrequency();
+-}
+-
+ #elif defined(_M_IX86) || defined(_M_X64)
+ 
+ #pragma intrinsic(__rdtsc)
+diff --git a/absl/base/internal/unscaledcycleclock_config.h b/absl/base/internal/unscaledcycleclock_config.h
+index 5e232c1a..83552fc5 100644
+--- a/absl/base/internal/unscaledcycleclock_config.h
++++ b/absl/base/internal/unscaledcycleclock_config.h
+@@ -22,7 +22,6 @@
+ // The following platforms have an implementation of a hardware counter.
+ #if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__) || \
+     ((defined(__powerpc__) || defined(__ppc__)) && defined(__GLIBC__)) || \
+-    defined(__riscv) ||     \
+     defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))
+ #define ABSL_HAVE_UNSCALED_CYCLECLOCK_IMPLEMENTATION 1
+ #else
+@@ -54,8 +53,8 @@
+ #if ABSL_USE_UNSCALED_CYCLECLOCK
+ // This macro can be used to test if UnscaledCycleClock::Frequency()
+ // is NominalCPUFrequency() on a particular platform.
+-#if (defined(__i386__) || defined(__x86_64__) || defined(__riscv) || \
+-     defined(_M_IX86) || defined(_M_X64))
++#if (defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || \
++     defined(_M_X64))
+ #define ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY
+ #endif
+ #endif
+-- 
+2.44.0
+

meta-oe/recipes-devtools/abseil-cpp/abseil-cpp_20240116.2.bb

@@ -14,6 +14,7 @@ SRC_URI = "git://github.com/abseil/abseil-cpp;branch=${BRANCH};protocol=https \
            file://0002-Remove-maes-option-from-cross-compilation.patch \
            file://abseil-ppc-fixes.patch \
            file://0003-Remove-neon-option-from-cross-compilation.patch \
+           file://0004-PR-1644-unscaledcycleclock-remove-RISC-V-support.patch \
           "
 
 S = "${WORKDIR}/git"