kernel.git/arch/arc/mm, branch linux-4.19.y

ARCv2: entry: push out the Z flag unclobber from common EXCEPTION_PROLOGUE

2023-08-11T09:45:10Z

[ Upstream commit 23c0cbd0c75c3b564850294427fd2be2bc2a015b ] Upon a taken interrupt/exception from User mode, HS hardware auto sets Z flag. This helps shave a few instructions from EXCEPTION_PROLOGUE by eliding re-reading ERSTATUS and some bit fiddling. However TLB Miss Exception handler can clobber the CPU flags and still end up in EXCEPTION_PROLOGUE in the slow path handling TLB handling case: EV_TLBMissD do_slow_path_pf EV_TLBProtV (aliased to call_do_page_fault) EXCEPTION_PROLOGUE As a result, EXCEPTION_PROLOGUE need to "unclobber" the Z flag which this patch changes. It is now pushed out to TLB Miss Exception handler. The reasons beings: - The flag restoration is only needed for slowpath TLB Miss Exception handling, but currently being in EXCEPTION_PROLOGUE penalizes all exceptions such as ProtV and syscall Trap, where Z flag is already as expected. - Pushing unclobber out to where it was clobbered is much cleaner and also serves to document the fact. - Makes EXCEPTION_PROLGUE similar to INTERRUPT_PROLOGUE so easier to refactor the common parts which is what this series aims to do Signed-off-by: Vineet Gupta Stable-dep-of: 92e2921eeafd ("ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guard") Signed-off-by: Sasha Levin

arc: iounmap() arg is volatile

2022-11-03T14:52:30Z

[ Upstream commit c44f15c1c09481d50fd33478ebb5b8284f8f5edb ] Add 'volatile' to iounmap()'s argument to prevent build warnings. This make it the same as other major architectures. Placates these warnings: (12 such warnings) ../drivers/video/fbdev/riva/fbdev.c: In function 'rivafb_probe': ../drivers/video/fbdev/riva/fbdev.c:2067:42: error: passing argument 1 of 'iounmap' discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers] 2067 | iounmap(default_par->riva.PRAMIN); Fixes: 1162b0701b14b ("ARC: I/O and DMA Mappings") Signed-off-by: Randy Dunlap Cc: Vineet Gupta Cc: linux-snps-arc@lists.infradead.org Cc: Arnd Bergmann Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: export clear_user_page() for modules

2021-09-22T09:48:13Z

[ Upstream commit 6b5ff0405e4190f23780362ea324b250bc495683 ] 0day bot reports a build error: ERROR: modpost: "clear_user_page" [drivers/media/v4l2-core/videobuf-dma-sg.ko] undefined! so export it in arch/arc/ to fix the build error. In most ARCHes, clear_user_page() is a macro. OTOH, in a few ARCHes it is a function and needs to be exported. PowerPC exported it in 2004. It looks like nds32 and nios2 still need to have it exported. Fixes: 4102b53392d63 ("ARC: [mm] Aliasing VIPT dcache support 2/4") Signed-off-by: Randy Dunlap Reported-by: kernel test robot Cc: Guenter Roeck Cc: linux-snps-arc@lists.infradead.org Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: IOC: panic if kernel was started with previously enabled IOC

2019-12-13T07:51:12Z

[ Upstream commit 3624379d90ad2b65f9dbb30d7f7ce5498d2fe322 ] If IOC was already enabled (due to bootloader) it technically needs to be reconfigured with aperture base,size corresponding to Linux memory map which will certainly be different than uboot's. But disabling and reenabling IOC when DMA might be potentially active is tricky business. To avoid random memory issues later, just panic here and ask user to upgrade bootloader to one which doesn't enable IOC This was actually seen as issue on some of the HSDK board with a version of uboot which enabled IOC. There were random issues later with starting of X or peripherals etc. Also while I'm at it, replace hardcoded bits in ARC_REG_IO_COH_PARTIAL and ARC_REG_IO_COH_ENABLE registers by definitions. Inspired by: https://lkml.org/lkml/2018/1/19/557 Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: mm: SIGSEGV userspace trying to access kernel virtual memory

2019-09-16T06:22:14Z

[ Upstream commit a8c715b4dd73c26a81a9cc8dc792aa715d8b4bb2 ] As of today if userspace process tries to access a kernel virtual addres (0x7000_0000 to 0x7ffff_ffff) such that a legit kernel mapping already exists, that process hangs instead of being killed with SIGSEGV Fix that by ensuring that do_page_fault() handles kenrel vaddr only if in kernel mode. And given this, we can also simplify the code a bit. Now a vmalloc fault implies kernel mode so its failure (for some reason) can reuse the @no_context label and we can remove @bad_area_nosemaphore. Reproduce user test for original problem: ------------------------>8----------------- #include #include int main(int argc, char *argv[]) { volatile uint32_t temp; temp = *(uint32_t *)(0x70000000); } ------------------------>8----------------- Cc: Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: mm: fix uninitialised signal code in do_page_fault

2019-09-16T06:22:14Z

[ Upstream commit 121e38e5acdc8e1e4cdb750fcdcc72f94e420968 ] Commit 15773ae938d8 ("signal/arc: Use force_sig_fault where appropriate") introduced undefined behaviour by leaving si_code unitiailized and leaking random kernel values to user space. Fixes: 15773ae938d8 ("signal/arc: Use force_sig_fault where appropriate") Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

signal/arc: Use force_sig_fault where appropriate

2019-09-16T06:22:14Z

[ Upstream commit 15773ae938d8d93d982461990bebad6e1d7a1830 ] Acked-by: Vineet Gupta Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin

ARC: mm: do_page_fault fixes #1: relinquish mmap_sem if signal arrives while handle_mm_fault

2019-09-16T06:22:02Z

[ Upstream commit 4d447455e73b47c43dd35fcc38ed823d3182a474 ] do_page_fault() forgot to relinquish mmap_sem if a signal came while handling handle_mm_fault() - due to say a ctl+c or oom etc. This would later cause a deadlock by acquiring it twice. This came to light when running libc testsuite tst-tls3-malloc test but is likely also the cause for prior seen LTP failures. Using lockdep clearly showed what the issue was. | # while true; do ./tst-tls3-malloc ; done | Didn't expect signal from child: got `Segmentation fault' | ^C | ============================================ | WARNING: possible recursive locking detected | 4.17.0+ #25 Not tainted | -------------------------------------------- | tst-tls3-malloc/510 is trying to acquire lock: | 606c7728 (&mm->mmap_sem){++++}, at: __might_fault+0x28/0x5c | |but task is already holding lock: |606c7728 (&mm->mmap_sem){++++}, at: do_page_fault+0x9c/0x2a0 | | other info that might help us debug this: | Possible unsafe locking scenario: | | CPU0 | ---- | lock(&mm->mmap_sem); | lock(&mm->mmap_sem); | | *** DEADLOCK *** | ------------------------------------------------------------ What the change does is not obvious (note to myself) prior code was | do_page_fault | | down_read() <-- lock taken | handle_mm_fault <-- signal pending as this runs | if fatal_signal_pending | if VM_FAULT_ERROR | up_read | if user_mode | return <-- lock still held, this was the BUG New code | do_page_fault | | down_read() <-- lock taken | handle_mm_fault <-- signal pending as this runs | if fatal_signal_pending | if VM_FAULT_RETRY | return <-- not same case as above, but still OK since | core mm already relinq lock for FAULT_RETRY | ... | | < Now falls through for bug case above > | | up_read() <-- lock relinquished Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: fix build warnings

2019-06-25T03:35:55Z

[ Upstream commit 89c92142f75eb80064f5b9f1111484b1b4d81790 ] | arch/arc/mm/tlb.c:914:2: warning: variable length array 'pd0' is used [-Wvla] | arch/arc/include/asm/cmpxchg.h:95:29: warning: value computed is not used [-Wunused-value] Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: adjust memblock_reserve of kernel memory

2019-01-31T07:14:35Z

commit a3010a0465383300f909f62b8a83f83ffa7b2517 upstream. In setup_arch_memory we reserve the memory area wherein the kernel is located. Current implementation may reserve more memory than it actually required in case of CONFIG_LINUX_LINK_BASE is not equal to CONFIG_LINUX_RAM_BASE. This happens because we calculate start of the reserved region relatively to the CONFIG_LINUX_RAM_BASE and end of the region relatively to the CONFIG_LINUX_RAM_BASE. For example in case of HSDK board we wasted 256MiB of physical memory: ------------------->8------------------------------ Memory: 770416K/1048576K available (5496K kernel code, 240K rwdata, 1064K rodata, 2200K init, 275K bss, 278160K reserved, 0K cma-reserved) ------------------->8------------------------------ Fix that. Fixes: 9ed68785f7f2b ("ARC: mm: Decouple RAM base address from kernel link addr") Cc: stable@vger.kernel.org #4.14+ Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman