Re: [PATCH] arm64: asm: vdso: gettimeofday: export common variables
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2021-10-11 13:33:20
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lkml
Subsystem:
generic vdso library, library code, the rest · Maintainers:
Andy Lutomirski, Thomas Gleixner, Vincenzo Frascino, Andrew Morton, Linus Torvalds
On Mon, Oct 11, 2021 at 02:47:56PM +0200, Arnd Bergmann wrote:
On Mon, Oct 11, 2021 at 12:03 PM Will Deacon [off-list ref] wrote:quoted
On Thu, Oct 07, 2021 at 09:57:54PM +0200, Anders Roxell wrote:quoted
When building the kernel with sparse enabled 'C=1' the following warnings can be seen: arch/arm64/kernel/vdso/vgettimeofday.c:9:5: warning: symbol '__kernel_clock_gettime' was not declared. Should it be static? arch/arm64/kernel/vdso/vgettimeofday.c:15:5: warning: symbol '__kernel_gettimeofday' was not declared. Should it be static? arch/arm64/kernel/vdso/vgettimeofday.c:21:5: warning: symbol '__kernel_clock_getres' was not declared. Should it be static? Rework so the variables are exported, since these variables are created and used in vdso/vgettimeofday.c, also used in vdso.lds.S.Hmm, these functions are part of the vDSO and shouldn't be called from the kernel, so I don't think it makes sense to add prototypes for them to a kernel header, to be honest.It's a recurring problem, and I have recommended this method to Anders as I don't see any of the alternatives as better. The thing is that both sparse (with make C=1) and gcc/clang (with make W=1) warn about missing prototypes, and this catches a lot of real bugs. I hope that we can eventually get to the point of enabling the warning by default for all files, but that means we need a declaration for each global function and variable.
I don't think there's anything in the asm/vdso/gettimeofday.h that is required by the kernel. However, it gets dragged in via the datapage.h. If I got it right, something like this should avoid it and we can include the prototypes:
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 73eb622e7663..a8d26d7d042d 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h@@ -121,22 +121,6 @@ struct vdso_data { extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden"))); extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden"))); -/* - * The generic vDSO implementation requires that gettimeofday.h - * provides: - * - __arch_get_vdso_data(): to get the vdso datapage. - * - __arch_get_hw_counter(): to get the hw counter based on the - * clock_mode. - * - gettimeofday_fallback(): fallback for gettimeofday. - * - clock_gettime_fallback(): fallback for clock_gettime. - * - clock_getres_fallback(): fallback for clock_getres. - */ -#ifdef ENABLE_COMPAT_VDSO -#include <asm/vdso/compat_gettimeofday.h> -#else -#include <asm/vdso/gettimeofday.h> -#endif /* ENABLE_COMPAT_VDSO */ - #endif /* !__ASSEMBLY__ */ #endif /* __VDSO_DATAPAGE_H */
diff --git a/include/vdso/gettimeofday.h b/include/vdso/gettimeofday.h
new file mode 100644
index 000000000000..0270da504fe3
--- /dev/null
+++ b/include/vdso/gettimeofday.h@@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * The generic vDSO implementation requires that gettimeofday.h + * provides: + * - __arch_get_vdso_data(): to get the vdso datapage. + * - __arch_get_hw_counter(): to get the hw counter based on the + * clock_mode. + * - gettimeofday_fallback(): fallback for gettimeofday. + * - clock_gettime_fallback(): fallback for clock_gettime. + * - clock_getres_fallback(): fallback for clock_getres. + */ +#ifdef ENABLE_COMPAT_VDSO +#include <asm/vdso/compat_gettimeofday.h> +#else +#include <asm/vdso/gettimeofday.h> +#endif /* ENABLE_COMPAT_VDSO */
diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
index 9a2af9fca45e..cb7a456323e3 100644
--- a/include/vdso/helpers.h
+++ b/include/vdso/helpers.h@@ -6,6 +6,8 @@ #include <vdso/datapage.h> +#include <asm/barrier.h> + static __always_inline u32 vdso_read_begin(const struct vdso_data *vd) { u32 seq;
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index ce2f69552003..8c1786ae59d8 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c@@ -3,6 +3,7 @@ * Generic userspace implementations of gettimeofday() and similar. */ #include <vdso/datapage.h> +#include <vdso/gettimeofday.h> #include <vdso/helpers.h> #ifndef vdso_calc_delta
--
Catalin
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