[PATCH] linux: arm: vdso: nullpatch vdso_clock_gettime64 for non-virtual timers

[Alex Bee]

Along with commit commit 74d06efb9c2f ("ARM: 8932/1: Add clock_gettime64
entry point") clock_gettime64 was added for ARM platform to solve the
y2k38 problem on 32-bit platforms. glibc from version 2.31 onwards
started using this vdso-call on ARM platforms.
However it was (probably) forgotten to "nullpatch" this call, when no
reliable timer source is available, for example when
"arm,cpu-registers-not-fw-configured" is defined in devicetree for
"arm,armv7-timer".
This results in erratic time jumps whenever "gettimeofday" gets called,
since the (non-working) vdso-call will be used instead of a syscall.

This patch adds clock_gettime64 to get nullpatched as well. It has been
verified to work and solve this issue on Rockchip RK322x, RK3288 and
RPi4 (32-bit kernel build) platforms.

Signed-off-by: Alex Bee <knaerzche at gmail.com>
---
 arch/arm/kernel/vdso.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 6bfdca4769a7..fddd08a6e063 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -184,6 +184,7 @@ static void __init patch_vdso(void *ehdr)
 	if (!cntvct_ok) {
 		vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
+		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
 	}
 }
 
-- 
2.17.1