Re: [PATCH v4 7/8] powerpc/vdso32: implement clock_getres entirely
From: Aurelien Jarno <aurelien@aurel32.net>
Date: 2020-05-05 23:23:12
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Hi, On 2019-12-02 07:57, Christophe Leroy wrote:
quoted hunk ↗ jump to hunk
clock_getres returns hrtimer_res for all clocks but coarse ones for which it returns KTIME_LOW_RES. return EINVAL for unknown clocks. Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/kernel/asm-offsets.c | 3 +++ arch/powerpc/kernel/vdso32/gettimeofday.S | 19 +++++++++++-------- 2 files changed, 14 insertions(+), 8 deletions(-)diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 0013197d89a6..90e53d432f2e 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c@@ -413,7 +413,10 @@ int main(void) DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); + DEFINE(CLOCK_MAX, CLOCK_TAI); DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); + DEFINE(EINVAL, EINVAL); + DEFINE(KTIME_LOW_RES, KTIME_LOW_RES); #ifdef CONFIG_BUG DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index 9aafacea9c4a..20ae38f3a5a3 100644 --- a/arch/powerpc/kernel/vdso32/gettimeofday.S +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S@@ -196,17 +196,20 @@ V_FUNCTION_END(__kernel_clock_gettime) V_FUNCTION_BEGIN(__kernel_clock_getres) .cfi_startproc /* Check for supported clock IDs */ - cmpwi cr0,r3,CLOCK_REALTIME - cmpwi cr1,r3,CLOCK_MONOTONIC - cror cr0*4+eq,cr0*4+eq,cr1*4+eq - bne cr0,99f + cmplwi cr0, r3, CLOCK_MAX + cmpwi cr1, r3, CLOCK_REALTIME_COARSE + cmpwi cr7, r3, CLOCK_MONOTONIC_COARSE + bgt cr0, 99f + LOAD_REG_IMMEDIATE(r5, KTIME_LOW_RES) + beq cr1, 1f + beq cr7, 1f mflr r12 .cfi_register lr,r12 get_datapage r3, r0 lwz r5, CLOCK_HRTIMER_RES(r3) mtlr r12 - li r3,0 +1: li r3,0 cmpli cr0,r4,0 crclr cr0*4+so beqlr@@ -215,11 +218,11 @@ V_FUNCTION_BEGIN(__kernel_clock_getres) blr /* - * syscall fallback + * invalid clock */ 99: - li r0,__NR_clock_getres - sc + li r3, EINVAL + crset so blr .cfi_endproc V_FUNCTION_END(__kernel_clock_getres)
Removing the syscall fallback looks wrong, and broke access to
per-processes clocks. With this change a few glibc tests now fail.
This can be reproduced by the simple code below:
| #include <errno.h>
| #include <stdio.h>
| #include <string.h>
| #include <sys/types.h>
| #include <time.h>
| #include <unistd.h>
|
| int main()
| {
| struct timespec res;
| clockid_t ci;
| int e;
|
| e = clock_getcpuclockid(getpid(), &ci);
| if (e) {
| printf("clock_getcpuclockid returned %d\n", e);
| return e;
| }
| e = clock_getres (ci, &res);
| printf("clock_getres returned %d\n", e);
| if (e) {
| printf(" errno: %d, %s\n", errno, strerror(errno));
| }
|
| return e;
| }
Without this patch or with -m64, it returns:
| clock_getres returned 0
With this patch with -m32 it returns:
| clock_getres returned -1
| errno: 22, Invalid argument
Regards,
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net