From 87f67cc4c7b81273fd1d9f775192eeb3124562f9 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Wed, 27 Nov 2019 07:26:12 -0800 Subject: MIPS: Fix boot on Fuloong2 systems MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 268a2d60013049 ("MIPS: Loongson64: Rename CPU TYPES") changed Kconfig symbols as follows: CPU_LOONGSON2 to CPU_LOONGSON2EF CPU_LOONGSON3 to CPU_LOONGSON64 SYS_HAS_CPU_LOONGSON3 to SYS_HAS_CPU_LOONGSON64 It did not touch SYS_HAS_CPU_LOONGSON2E or SYS_HAS_CPU_LOONGSON2F. However, the patch changed a conditional from #if defined(CONFIG_SYS_HAS_CPU_LOONGSON2E) || \ defined(CONFIG_SYS_HAS_CPU_LOONGSON2F) to #if defined(CONFIG_SYS_HAS_CPU_LOONGSON2EF) SYS_HAS_CPU_LOONGSON2EF does not exist, resulting in boot failures with the qemu fulong2e emulation. Revert to the original code. Fixes: 268a2d60013049 ("MIPS: Loongson64: Rename CPU TYPES") Cc: Jiaxun Yang Signed-off-by: Guenter Roeck Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Paul Burton Cc: Ralf Baechle Cc: James Hogan Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- arch/mips/include/asm/cpu-type.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/mips/include') diff --git a/arch/mips/include/asm/cpu-type.h b/arch/mips/include/asm/cpu-type.h index c46c59b0f1b4..49f0061a6051 100644 --- a/arch/mips/include/asm/cpu-type.h +++ b/arch/mips/include/asm/cpu-type.h @@ -15,7 +15,8 @@ static inline int __pure __get_cpu_type(const int cpu_type) { switch (cpu_type) { -#if defined(CONFIG_SYS_HAS_CPU_LOONGSON2EF) +#if defined(CONFIG_SYS_HAS_CPU_LOONGSON2E) || \ + defined(CONFIG_SYS_HAS_CPU_LOONGSON2F) case CPU_LOONGSON2EF: #endif -- cgit v1.2.3 From 7d2aa4bb90f5f6f1b8de8848c26042403f2d7bf9 Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino Date: Fri, 29 Nov 2019 14:36:58 +0000 Subject: mips: Fix gettimeofday() in the vdso library The libc provides a discovery mechanism for vDSO library and its symbols. When a symbol is not exposed by the vDSOs the libc falls back on the system calls. With the introduction of the unified vDSO library on mips this behavior is not honored anymore by the kernel in the case of gettimeofday(). The issue has been noticed and reported due to a dhclient failure on the CI20 board: root@letux:~# dhclient ../../../../lib/isc/unix/time.c:200: Operation not permitted root@letux:~# Restore the original behavior fixing gettimeofday() in the vDSO library. Reported-by: H. Nikolaus Schaller Tested-by: H. Nikolaus Schaller # CI20 with JZ4780 Signed-off-by: Vincenzo Frascino Signed-off-by: Paul Burton Cc: mips-creator-ci20-dev@googlegroups.com Cc: letux-kernel@openphoenux.org Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- arch/mips/include/asm/vdso/gettimeofday.h | 13 ------------- 1 file changed, 13 deletions(-) (limited to 'arch/mips/include') diff --git a/arch/mips/include/asm/vdso/gettimeofday.h b/arch/mips/include/asm/vdso/gettimeofday.h index b08825531e9f..0ae9b4cbc153 100644 --- a/arch/mips/include/asm/vdso/gettimeofday.h +++ b/arch/mips/include/asm/vdso/gettimeofday.h @@ -26,8 +26,6 @@ #define __VDSO_USE_SYSCALL ULLONG_MAX -#ifdef CONFIG_MIPS_CLOCK_VSYSCALL - static __always_inline long gettimeofday_fallback( struct __kernel_old_timeval *_tv, struct timezone *_tz) @@ -48,17 +46,6 @@ static __always_inline long gettimeofday_fallback( return error ? -ret : ret; } -#else - -static __always_inline long gettimeofday_fallback( - struct __kernel_old_timeval *_tv, - struct timezone *_tz) -{ - return -1; -} - -#endif - static __always_inline long clock_gettime_fallback( clockid_t _clkid, struct __kernel_timespec *_ts) -- cgit v1.2.3 From bbcc5672b0063b0e9d65dc8787a4f09c3b5bb5cc Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Wed, 1 Jan 2020 20:50:38 -0800 Subject: MIPS: Avoid VDSO ABI breakage due to global register variable Declaring __current_thread_info as a global register variable has the effect of preventing GCC from saving & restoring its value in cases where the ABI would typically do so. To quote GCC documentation: > If the register is a call-saved register, call ABI is affected: the > register will not be restored in function epilogue sequences after the > variable has been assigned. Therefore, functions cannot safely return > to callers that assume standard ABI. When our position independent VDSO is built for the n32 or n64 ABIs all functions it exposes should be preserving the value of $gp/$28 for their caller, but in the presence of the __current_thread_info global register variable GCC stops doing so & simply clobbers $gp/$28 when calculating the address of the GOT. In cases where the VDSO returns success this problem will typically be masked by the caller in libc returning & restoring $gp/$28 itself, but that is by no means guaranteed. In cases where the VDSO returns an error libc will typically contain a fallback path which will now fail (typically with a bad memory access) if it attempts anything which relies upon the value of $gp/$28 - eg. accessing anything via the GOT. One fix for this would be to move the declaration of __current_thread_info inside the current_thread_info() function, demoting it from global register variable to local register variable & avoiding inadvertently creating a non-standard calling ABI for the VDSO. Unfortunately this causes issues for clang, which doesn't support local register variables as pointed out by commit fe92da0f355e ("MIPS: Changed current_thread_info() to an equivalent supported by both clang and GCC") which introduced the global register variable before we had a VDSO to worry about. Instead, fix this by continuing to use the global register variable for the kernel proper but declare __current_thread_info as a simple extern variable when building the VDSO. It should never be referenced, and will cause a link error if it is. This resolves the calling convention issue for the VDSO without having any impact upon the build of the kernel itself for either clang or gcc. Signed-off-by: Paul Burton Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Reported-by: Jason A. Donenfeld Reviewed-by: Jason A. Donenfeld Tested-by: Jason A. Donenfeld Cc: Arnd Bergmann Cc: Christian Brauner Cc: Vincenzo Frascino Cc: # v4.4+ Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- arch/mips/include/asm/thread_info.h | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'arch/mips/include') diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h index 4993db40482c..ee26f9a4575d 100644 --- a/arch/mips/include/asm/thread_info.h +++ b/arch/mips/include/asm/thread_info.h @@ -49,8 +49,26 @@ struct thread_info { .addr_limit = KERNEL_DS, \ } -/* How to get the thread information struct from C. */ +/* + * A pointer to the struct thread_info for the currently executing thread is + * held in register $28/$gp. + * + * We declare __current_thread_info as a global register variable rather than a + * local register variable within current_thread_info() because clang doesn't + * support explicit local register variables. + * + * When building the VDSO we take care not to declare the global register + * variable because this causes GCC to not preserve the value of $28/$gp in + * functions that change its value (which is common in the PIC VDSO when + * accessing the GOT). Since the VDSO shouldn't be accessing + * __current_thread_info anyway we declare it extern in order to cause a link + * failure if it's referenced. + */ +#ifdef __VDSO__ +extern struct thread_info *__current_thread_info; +#else register struct thread_info *__current_thread_info __asm__("$28"); +#endif static inline struct thread_info *current_thread_info(void) { -- cgit v1.2.3