This series implements SBI PMU improvements done in SBI v2.0[1] i.e. PMU snapshot
and fw_read_hi() functions.
SBI v2.0 introduced PMU snapshot feature which allows the SBI implementation
to provide counter information (i.e. values/overflow status) via a shared
memory between the SBI implementation and supervisor OS. This allows to minimize
the number of traps in when perf being used inside a kvm guest as it relies on
SBI PMU + trap/emulation of the counters.
The current set of ratified RISC-V specification also doesn't allow scountovf
to be trap/emulated by the hypervisor. The SBI PMU snapshot bridges the gap
in ISA as well and enables perf sampling in the guest. However, LCOFI in the
guest only works via IRQ filtering in AIA specification. That's why, AIA
has to be enabled in the hardware (at least the Ssaia extension) in order to
use the sampling support in the perf.
Here are the patch wise implementation details.
PATCH 1,4,7,8,9,10,11,15 : Generic cleanups/improvements.
PATCH 2,3,14 : FW_READ_HI function implementation
PATCH 5-6: Add PMU snapshot feature in sbi pmu driver
PATCH 12-13: KVM implementation for snapshot and sampling in kvm guests
PATCH 16-17: Generic improvements for kvm selftests
PATCH 18-22: KVM selftests for SBI PMU extension
The series is based on v6.9-rc4 and is available at:
https://github.com/atishp04/linux/tree/kvm_pmu_snapshot_v8
The kvmtool patch is also available at:
https://github.com/atishp04/kvmtool/tree/sscofpmf
It also requires Ssaia ISA extension to be present in the hardware in order to
get perf sampling support in the guest. In Qemu virt machine, it can be done
by the following config.
```
-cpu rv64,sscofpmf=true,x-ssaia=true
```
There is no other dependencies on AIA apart from that. Thus, Ssaia must be disabled
for the guest if AIA patches are not available. Here is the example command.
```
./lkvm-static run -m 256 -c2 --console serial -p "console=ttyS0 earlycon" --disable-ssaia -k ./Image --debug
```
The series has been tested only in Qemu.
Here is the snippet of the perf running inside a kvm guest.
===================================================
$ perf record -e cycles -e instructions perf bench sched messaging -g 5
...
$ Running 'sched/messaging' benchmark:
...
[ 45.928723] perf_duration_warn: 2 callbacks suppressed
[ 45.929000] perf: interrupt took too long (484426 > 483186), lowering kernel.perf_event_max_sample_rate to 250
$ 20 sender and receiver processes per group
$ 5 groups == 200 processes run
Total time: 14.220 [sec]
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.117 MB perf.data (1942 samples) ]
$ perf report --stdio
$ To display the perf.data header info, please use --header/--header-only optio>
$
$
$ Total Lost Samples: 0
$
$ Samples: 943 of event 'cycles'
$ Event count (approx.): 5128976844
$
$ Overhead Command Shared Object Symbol >
$ ........ ............... ........................... .....................>
$
7.59% sched-messaging [kernel.kallsyms] [k] memcpy
5.48% sched-messaging [kernel.kallsyms] [k] percpu_counter_ad>
5.24% sched-messaging [kernel.kallsyms] [k] __sbi_rfence_v02_>
4.00% sched-messaging [kernel.kallsyms] [k] _raw_spin_unlock_>
3.79% sched-messaging [kernel.kallsyms] [k] set_pte_range
3.72% sched-messaging [kernel.kallsyms] [k] next_uptodate_fol>
3.46% sched-messaging [kernel.kallsyms] [k] filemap_map_pages
3.31% sched-messaging [kernel.kallsyms] [k] handle_mm_fault
3.20% sched-messaging [kernel.kallsyms] [k] finish_task_switc>
3.16% sched-messaging [kernel.kallsyms] [k] clear_page
3.03% sched-messaging [kernel.kallsyms] [k] mtree_range_walk
2.42% sched-messaging [kernel.kallsyms] [k] flush_icache_pte
===================================================
[1] https://github.com/riscv-non-isa/riscv-sbi-doc
Changes from v7->v8:
1. Updated event states so that shared memory is updated only during stop
operations.
2. Avoid clobbering lower XLEN counter/overflow values in shared memory
by maintaining a temporary copy for RV32.
3. Improved overflow handling in snapshot case by supporting all 64 values.
4. Minor cleanups based on suggestions on v7.
Changes from v6->v7:
1. Used SBI_SHMEM_DISABLE in the driver.
2. Added RB Tags.
3. Improved the sbi_pmu_test commandline to allow disabling multiple
tests.
Changes from v5->v6:
1. Added a patch for command line option for the sbi pmu tests.
2. Removed redundant prints and restructure the code little bit.
3. Added a patch for computing the sbi minor version correctly.
4. Addressed all other comments on v5.
Changes from v4->v5:
1. Moved sbi related definitions to its own header file from processor.h
2. Added few helper functions for selftests.
3. Improved firmware counter read and RV32 start/stop functions.
4. Converted all the shifting operations to use BIT macro
5. Addressed all other comments on v4.
Changes from v3->v4:
1. Added selftests.
2. Fixed an issue to clear the interrupt pending bits.
3. Fixed the counter index in snapshot memory start function.
Changes from v2->v3:
1. Fixed a patchwork warning on patch6.
2. Fixed a comment formatting & nit fix in PATCH 3 & 5.
3. Moved the hvien update and sscofpmf enabling to PATCH 9 from PATCH 8.
Changes from v1->v2:
1. Fixed warning/errors from patchwork CI.
2. Rebased on top of kvm-next.
3. Added Acked-by tags.
Changes from RFC->v1:
1. Addressed all the comments on RFC series.
2. Removed PATCH2 and merged into later patches.
3. Added 2 more patches for minor fixes.
4. Fixed KVM boot issue without Ssaia and made sscofpmf in guest dependent on
Ssaia in the host.
Atish Patra (24):
RISC-V: Fix the typo in Scountovf CSR name
RISC-V: Add FIRMWARE_READ_HI definition
drivers/perf: riscv: Read upper bits of a firmware counter
drivers/perf: riscv: Use BIT macro for shifting operations
RISC-V: Add SBI PMU snapshot definitions
RISC-V: KVM: Rename the SBI_STA_SHMEM_DISABLE to a generic name
RISC-V: Use the minor version mask while computing sbi version
drivers/perf: riscv: Fix counter mask iteration for RV32
drivers/perf: riscv: Implement SBI PMU snapshot function
RISC-V: KVM: Fix the initial sample period value
RISC-V: KVM: No need to update the counter value during reset
RISC-V: KVM: No need to exit to the user space if perf event failed
RISC-V: KVM: Implement SBI PMU Snapshot feature
RISC-V: KVM: Add perf sampling support for guests
RISC-V: KVM: Support 64 bit firmware counters on RV32
RISC-V: KVM: Improve firmware counter read function
KVM: riscv: selftests: Move sbi definitions to its own header file
KVM: riscv: selftests: Add helper functions for extension checks
KVM: riscv: selftests: Add Sscofpmf to get-reg-list test
KVM: riscv: selftests: Add SBI PMU extension definitions
KVM: riscv: selftests: Add SBI PMU selftest
KVM: riscv: selftests: Add a test for PMU snapshot functionality
KVM: riscv: selftests: Add a test for counter overflow
KVM: riscv: selftests: Add commandline option for SBI PMU test
arch/riscv/include/asm/csr.h | 5 +-
arch/riscv/include/asm/kvm_vcpu_pmu.h | 16 +-
arch/riscv/include/asm/sbi.h | 38 +-
arch/riscv/include/uapi/asm/kvm.h | 1 +
arch/riscv/kernel/paravirt.c | 6 +-
arch/riscv/kvm/aia.c | 5 +
arch/riscv/kvm/vcpu.c | 15 +-
arch/riscv/kvm/vcpu_onereg.c | 6 +
arch/riscv/kvm/vcpu_pmu.c | 260 ++++++-
arch/riscv/kvm/vcpu_sbi_pmu.c | 17 +-
arch/riscv/kvm/vcpu_sbi_sta.c | 4 +-
drivers/perf/riscv_pmu.c | 1 +
drivers/perf/riscv_pmu_sbi.c | 309 +++++++-
include/linux/perf/riscv_pmu.h | 6 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/riscv/processor.h | 49 +-
.../testing/selftests/kvm/include/riscv/sbi.h | 141 ++++
.../selftests/kvm/include/riscv/ucall.h | 1 +
.../selftests/kvm/lib/riscv/processor.c | 12 +
.../testing/selftests/kvm/riscv/arch_timer.c | 2 +-
.../selftests/kvm/riscv/get-reg-list.c | 4 +
.../selftests/kvm/riscv/sbi_pmu_test.c | 681 ++++++++++++++++++
tools/testing/selftests/kvm/steal_time.c | 4 +-
23 files changed, 1467 insertions(+), 117 deletions(-)
create mode 100644 tools/testing/selftests/kvm/include/riscv/sbi.h
create mode 100644 tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
--
2.34.1
From: Mark Brown <broonie(a)kernel.org>
[ Upstream commit 907f33028871fa7c9a3db1efd467b78ef82cce20 ]
The standard library perror() function provides a convenient way to print
an error message based on the current errno but this doesn't play nicely
with KTAP output. Provide a helper which does an equivalent thing in a KTAP
compatible format.
nolibc doesn't have a strerror() and adding the table of strings required
doesn't seem like a good fit for what it's trying to do so when we're using
that only print the errno.
Signed-off-by: Mark Brown <broonie(a)kernel.org>
Reviewed-by: Kees Cook <keescook(a)chromium.org>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Stable-dep-of: 071af0c9e582 ("selftests: timers: Convert posix_timers test to generate KTAP output")
Signed-off-by: Edward Liaw <edliaw(a)google.com>
---
tools/testing/selftests/kselftest.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
index e8eecbc83a60..ad7b97e16f37 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -48,6 +48,7 @@
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
+#include <string.h>
#include <stdio.h>
#include <sys/utsname.h>
#endif
@@ -156,6 +157,19 @@ static inline void ksft_print_msg(const char *msg, ...)
va_end(args);
}
+static inline void ksft_perror(const char *msg)
+{
+#ifndef NOLIBC
+ ksft_print_msg("%s: %s (%d)\n", msg, strerror(errno), errno);
+#else
+ /*
+ * nolibc doesn't provide strerror() and it seems
+ * inappropriate to add one, just print the errno.
+ */
+ ksft_print_msg("%s: %d)\n", msg, errno);
+#endif
+}
+
static inline void ksft_test_result_pass(const char *msg, ...)
{
int saved_errno = errno;
--
2.44.0.769.g3c40516874-goog
Fixes clang compiler warnings by adding parentheses:
parse_vdso.c:65:9: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
if (g = h & 0xf0000000)
~~^~~~~~~~~~~~~~~~
parse_vdso.c:65:9: note: place parentheses around the assignment to silence this warning
if (g = h & 0xf0000000)
^
( )
parse_vdso.c:65:9: note: use '==' to turn this assignment into an equality comparison
if (g = h & 0xf0000000)
^
==
Fixes: 98eedc3a9dbf ("Document the vDSO and add a reference parser")
Signed-off-by: Edward Liaw <edliaw(a)google.com>
---
tools/testing/selftests/vDSO/parse_vdso.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35..b9cf771006da 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -62,7 +62,7 @@ static unsigned long elf_hash(const unsigned char *name)
while (*name)
{
h = (h << 4) + *name++;
- if (g = h & 0xf0000000)
+ if ((g = h & 0xf0000000))
h ^= g >> 24;
h &= ~g;
}
--
2.44.0.769.g3c40516874-goog
Currently, the migration worker delays 1-10 us, assuming that one
KVM_RUN iteration only takes a few microseconds. But if the CPU low
power wakeup latency is large enough, for example, hundreds or even
thousands of microseconds deep C-state exit latencies on x86 server
CPUs, it may happen that it's not able to wakeup the target CPU before
the migration worker starts to migrate the vCPU thread to the next CPU.
If the system workload is light, most CPUs could be at a certain low
power state, which may result in less successful migrations and fail the
migration/KVM_RUN ratio sanity check. But this is not supposed to be
deemed a test failure.
This patch adds a command line option to skip the sanity check in
this case.
Signed-off-by: Zide Chen <zide.chen(a)intel.com>
Signed-off-by: donsheng <dongsheng.x.zhang(a)intel.com>
V2:
- removed the busy loop implementation
- add the new "-s" option
V3:
- drop the usleep randomization code
- removed the term C-state for less confusion for non-x86 archetectures
- changed subject
---
tools/testing/selftests/kvm/rseq_test.c | 40 +++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
index 28f97fb52044..1daac3f51447 100644
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -186,12 +186,35 @@ static void calc_min_max_cpu(void)
"Only one usable CPU, task migration not possible");
}
+static void help(const char *name)
+{
+ puts("");
+ printf("usage: %s [-h] [-s]\n", name);
+ printf(" -s: skip the sanity check for successful KVM_RUN.\n");
+ puts("");
+ exit(0);
+}
+
int main(int argc, char *argv[])
{
int r, i, snapshot;
struct kvm_vm *vm;
struct kvm_vcpu *vcpu;
u32 cpu, rseq_cpu;
+ bool skip_sanity_check = false;
+ int opt;
+
+ while ((opt = getopt(argc, argv, "sh")) != -1) {
+ switch (opt) {
+ case 's':
+ skip_sanity_check = true;
+ break;
+ case 'h':
+ default:
+ help(argv[0]);
+ break;
+ }
+ }
r = sched_getaffinity(0, sizeof(possible_mask), &possible_mask);
TEST_ASSERT(!r, "sched_getaffinity failed, errno = %d (%s)", errno,
@@ -254,9 +277,22 @@ int main(int argc, char *argv[])
* getcpu() to stabilize. A 2:1 migration:KVM_RUN ratio is a fairly
* conservative ratio on x86-64, which can do _more_ KVM_RUNs than
* migrations given the 1us+ delay in the migration task.
+ *
+ * Another reason why it may have small migration:KVM_RUN ratio is that,
+ * on systems with large low power mode wakeup latency, it may happen
+ * quite often that the scheduler is not able to wake up the target CPU
+ * before the vCPU thread is scheduled to another CPU.
*/
- TEST_ASSERT(i > (NR_TASK_MIGRATIONS / 2),
- "Only performed %d KVM_RUNs, task stalled too much?", i);
+ TEST_ASSERT(skip_sanity_check || i > (NR_TASK_MIGRATIONS / 1),
+ "Only performed %d KVM_RUNs, task stalled too much? \n"
+ " Try to run it with -s option, or disable deep sleep "
+ "states in the system,\n"
+ " e.g., boot the host with cpuidle.off=1 or other driver "
+ "specific kernel options,\n"
+ " or do it through the PM QoS interface at runtime: \n"
+ " cat > /dev/cpu_dma_latency <(echo -e -n "
+ "\"\\x0\\x0\\x0\\x0\"; sleep inf) &\n"
+ " PID=$! && run_the_test && kill $PID" , i);
pthread_join(migration_thread, NULL);
--
2.34.1
Fixes clang compilation warnings by adding explicit unsigned conversion:
parse_vdso.c:206:22: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
ver_hash = elf_hash(version);
^~~~~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)
^
parse_vdso.c:207:46: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
^~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)
Fixes: 98eedc3a9dbf ("Document the vDSO and add a reference parser")
Signed-off-by: Edward Liaw <edliaw(a)google.com>
---
v2: update commit message with correct compiler warning
---
tools/testing/selftests/vDSO/parse_vdso.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35..7e2ea9bea394 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -203,8 +203,8 @@ void *vdso_sym(const char *version, const char *name)
if (!vdso_info.valid)
return 0;
- ver_hash = elf_hash(version);
- ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
+ ver_hash = elf_hash((const unsigned char *)version);
+ ELF(Word) chain = vdso_info.bucket[elf_hash((const unsigned char *)name) % vdso_info.nbucket];
for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
ELF(Sym) *sym = &vdso_info.symtab[chain];
--
2.44.0.769.g3c40516874-goog
If this feature is not supported or is disabled by IA32_MISC_ENABLE on
the host, executing MONITOR or MWAIT instruction from the guest doesn't
cause monitor/mwait VM exits, but a #UD.
So, we need to skip this test if CPUID.01H:ECX[3] is cleared.
Signed-off-by: Zide Chen <zide.chen(a)intel.com>
---
tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
index 853802641e1e..cdbfcf7cac5c 100644
--- a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
+++ b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
@@ -75,6 +75,7 @@ int main(int argc, char *argv[])
struct ucall uc;
int testcase;
+ TEST_REQUIRE(this_cpu_has(X86_FEATURE_MWAIT));
TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
--
2.34.1
I ran into a failure running this test on a minimal rootfs.
Can be fixed by just skipping the "sudo" in case we are already root.
Signed-off-by: Brendan Jackman <jackmanb(a)google.com>
---
tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
index 7cbb409801eea..0e56822e8e0bf 100755
--- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
+++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
@@ -13,10 +13,21 @@ NX_HUGE_PAGES_RECOVERY_RATIO=$(cat /sys/module/kvm/parameters/nx_huge_pages_reco
NX_HUGE_PAGES_RECOVERY_PERIOD=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms)
HUGE_PAGES=$(cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages)
+# If we're already root, the host might not have sudo.
+if [ $(whoami) == "root" ]; then
+ function maybe_sudo () {
+ "$@"
+ }
+else
+ function maybe_sudo () {
+ sudo "$@"
+ }
+fi
+
set +e
function sudo_echo () {
- echo "$1" | sudo tee -a "$2" > /dev/null
+ echo "$1" | maybe_sudo tee -a "$2" > /dev/null
}
NXECUTABLE="$(dirname $0)/nx_huge_pages_test"
---
base-commit: 2c71fdf02a95b3dd425b42f28fd47fb2b1d22702
change-id: 20240415-kvm-selftests-no-sudo-1a55f831f882
Best regards,
--
Brendan Jackman <jackmanb(a)google.com>
There is a statement with two semicolons. Remove the second one, it
is redundant.
Signed-off-by: Colin Ian King <colin.i.king(a)gmail.com>
---
tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index d2ea0435f4f7..7d707d8068a4 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -125,7 +125,7 @@ struct compat_vcpu_runstate_info {
uint32_t state;
uint64_t state_entry_time;
uint64_t time[5];
-} __attribute__((__packed__));;
+} __attribute__((__packed__));
struct arch_vcpu_info {
unsigned long cr2;
--
2.39.2
Fixes clang compilation warnings by adding explicit unsigned conversion:
parse_vdso.c:206:22: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
ver_hash = elf_hash((const char *)version);
^~~~~~~~~~~~~~~~~~~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)
^
parse_vdso.c:207:46: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
ELF(Word) chain = vdso_info.bucket[elf_hash((const char *)name) % vdso_info.nbucket];
^~~~~~~~~~~~~~~~~~
parse_vdso.c:59:52: note: passing argument to parameter 'name' here
static unsigned long elf_hash(const unsigned char *name)
Fixes: 98eedc3a9dbf ("Document the vDSO and add a reference parser")
Signed-off-by: Edward Liaw <edliaw(a)google.com>
---
tools/testing/selftests/vDSO/parse_vdso.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35..7e2ea9bea394 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -203,8 +203,8 @@ void *vdso_sym(const char *version, const char *name)
if (!vdso_info.valid)
return 0;
- ver_hash = elf_hash(version);
- ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
+ ver_hash = elf_hash((const unsigned char *)version);
+ ELF(Word) chain = vdso_info.bucket[elf_hash((const unsigned char *)name) % vdso_info.nbucket];
for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
ELF(Sym) *sym = &vdso_info.symtab[chain];
--
2.44.0.769.g3c40516874-goog