On Thu, Sep 05, 2024 at 07:03:34PM +0200, Jason A. Donenfeld wrote:
On Thu, Sep 05, 2024 at 06:55:27PM +0200, Christophe Leroy wrote:
Le 05/09/2024 à 18:13, Jason A. Donenfeld a écrit :
+/*
- The macro sets two stack frames, one for the caller and one for the callee
- because there are no requirement for the caller to set a stack frame when
- calling VDSO so it may have omitted to set one, especially on PPC64
- */
+.macro cvdso_call funct
- .cfi_startproc
- PPC_STLU r1, -PPC_MIN_STKFRM(r1)
- .cfi_adjust_cfa_offset PPC_MIN_STKFRM
- mflr r0
- PPC_STLU r1, -PPC_MIN_STKFRM(r1)
- .cfi_adjust_cfa_offset PPC_MIN_STKFRM
- PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
- .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
- get_datapage r8
- addi r8, r8, VDSO_RNG_DATA_OFFSET
- bl CFUNC(DOTSYM(\funct))
- PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
- cmpwi r3, 0
- mtlr r0
- addi r1, r1, 2 * PPC_MIN_STKFRM
- .cfi_restore lr
- .cfi_def_cfa_offset 0
- crclr so
- bgelr+
- crset so
- neg r3, r3
- blr
- .cfi_endproc
+.endm
You wrote in an earlier email that this worked with time namespaces, but in my testing that doesn't seem to be the case.
Did I write that ? I can't remember and neither can I remember testing it with time namespaces.
It's possible I confused you with someone else? Hum. Anyway...
From my test harness [1]:
Normal single thread vdso: 25000000 times in 12.494133131 seconds libc: 25000000 times in 69.594625188 seconds syscall: 25000000 times in 67.349243972 seconds Time namespace single thread vdso: 25000000 times in 71.673057436 seconds libc: 25000000 times in 71.712774121 seconds syscall: 25000000 times in 66.902318080 seconds
I'm seeing this on ppc, ppc64, and ppc64le.
What is the command to use to test with time namespace ?
Look at the C in the commit I linked.
The below also seems to work well for testing on x86. I'll clean that up and send a patch to the list.
diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c index 8866b65a4605..4df80f769aa7 100644 --- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c +++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c @@ -16,8 +16,11 @@ #include <sys/mman.h> #include <sys/random.h> #include <sys/syscall.h> +#include <sys/ptrace.h> +#include <sys/wait.h> #include <sys/types.h> #include <linux/random.h> +#include <linux/ptrace.h>
#include "../kselftest.h" #include "parse_vdso.h" @@ -239,9 +242,10 @@ static void fill(void) static void kselftest(void) { uint8_t weird_size[1263]; + pid_t child;
ksft_print_header(); - ksft_set_plan(1); + ksft_set_plan(2);
for (size_t i = 0; i < 1000; ++i) { ssize_t ret = vgetrandom(weird_size, sizeof(weird_size), 0); @@ -250,6 +254,39 @@ static void kselftest(void) }
ksft_test_result_pass("getrandom: PASS\n"); + + assert(unshare(CLONE_NEWTIME) == 0); + child = fork(); + assert(child >= 0); + + if (!child) { + vgetrandom_init(); + child = getpid(); + assert(ptrace(PTRACE_TRACEME, 0, NULL, NULL) == 0); + assert(kill(child, SIGSTOP) == 0); + assert(vgetrandom(weird_size, sizeof(weird_size), 0) == sizeof(weird_size)); + _exit(0); + } + for (;;) { + struct ptrace_syscall_info info = { 0 }; + int status, ret; + assert(waitpid(child, &status, 0) >= 0); + if (WIFEXITED(status)) + break; + assert(WIFSTOPPED(status)); + if (WSTOPSIG(status) == SIGSTOP) + assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD) == 0); + else if (WSTOPSIG(status) == SIGTRAP | 0x80) { + assert(ptrace(PTRACE_GET_SYSCALL_INFO, child, sizeof(info), &info) > 0); + if (info.entry.nr == __NR_getrandom && + ((void *)info.entry.args[0] == &weird_size && info.entry.args[1] == sizeof(weird_size))) + exit(KSFT_FAIL); + } + assert(ptrace(PTRACE_SYSCALL, child, 0, 0) == 0); + } + + ksft_test_result_pass("getrandom timens: PASS\n"); + exit(KSFT_PASS); }