From 612695bccfdbd52004551308a55bae410e7cd22f Mon Sep 17 00:00:00 2001 From: Tomislav Novak Date: Mon, 26 Sep 2022 16:09:12 +0100 Subject: ARM: 9251/1: perf: Fix stacktraces for tracepoint events in THUMB2 kernels Store the frame address where arm_get_current_stackframe() looks for it (ARM_r7 instead of ARM_fp if CONFIG_THUMB2_KERNEL=y). Otherwise frame->fp gets set to 0, causing unwind_frame() to fail. # bpftrace -e 't:sched:sched_switch { @[kstack] = count(); exit(); }' Attaching 1 probe... @[ __schedule+1059 ]: 1 A typical first unwind instruction is 0x97 (SP = R7), so after executing it SP ends up being 0 and -URC_FAILURE is returned. unwind_frame(pc = ac9da7d7 lr = 00000000 sp = c69bdda0 fp = 00000000) unwind_find_idx(ac9da7d7) unwind_exec_insn: insn = 00000097 unwind_exec_insn: fp = 00000000 sp = 00000000 lr = 00000000 pc = 00000000 With this patch: # bpftrace -e 't:sched:sched_switch { @[kstack] = count(); exit(); }' Attaching 1 probe... @[ __schedule+1059 __schedule+1059 schedule+79 schedule_hrtimeout_range_clock+163 schedule_hrtimeout_range+17 ep_poll+471 SyS_epoll_wait+111 sys_epoll_pwait+231 __ret_fast_syscall+1 ]: 1 Link: https://lore.kernel.org/r/20220920230728.2617421-1-tnovak@fb.com/ Reviewed-by: Linus Walleij Signed-off-by: Tomislav Novak Signed-off-by: Russell King (Oracle) --- arch/arm/include/asm/perf_event.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h index fe87397c3d8c..bdbc1e590891 100644 --- a/arch/arm/include/asm/perf_event.h +++ b/arch/arm/include/asm/perf_event.h @@ -17,7 +17,7 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); #define perf_arch_fetch_caller_regs(regs, __ip) { \ (regs)->ARM_pc = (__ip); \ - (regs)->ARM_fp = (unsigned long) __builtin_frame_address(0); \ + frame_pointer((regs)) = (unsigned long) __builtin_frame_address(0); \ (regs)->ARM_sp = current_stack_pointer; \ (regs)->ARM_cpsr = SVC_MODE; \ } -- cgit From 340a982825f76f1cff0daa605970fe47321b5ee7 Mon Sep 17 00:00:00 2001 From: Giulio Benetti Date: Fri, 4 Nov 2022 21:46:18 +0100 Subject: ARM: 9266/1: mm: fix no-MMU ZERO_PAGE() implementation Actually in no-MMU SoCs(i.e. i.MXRT) ZERO_PAGE(vaddr) expands to ``` virt_to_page(0) ``` that in order expands to: ``` pfn_to_page(virt_to_pfn(0)) ``` and then virt_to_pfn(0) to: ``` ((((unsigned long)(0) - PAGE_OFFSET) >> PAGE_SHIFT) + PHYS_PFN_OFFSET) ``` where PAGE_OFFSET and PHYS_PFN_OFFSET are the DRAM offset(0x80000000) and PAGE_SHIFT is 12. This way we obtain 16MB(0x01000000) summed to the base of DRAM(0x80000000). When ZERO_PAGE(0) is then used, for example in bio_add_page(), the page gets an address that is out of DRAM bounds. So instead of using fake virtual page 0 let's allocate a dedicated zero_page during paging_init() and assign it to a global 'struct page * empty_zero_page' the same way mmu.c does and it's the same approach used in m68k with commit dc068f462179 as discussed here[0]. Then let's move ZERO_PAGE() definition to the top of pgtable.h to be in common between mmu.c and nommu.c. [0]: https://lore.kernel.org/linux-m68k/2a462b23-5b8e-bbf4-ec7d-778434a3b9d7@google.com/T/#m1266ceb63 ad140743174d6b3070364d3c9a5179b Signed-off-by: Giulio Benetti Reviewed-by: Arnd Bergmann Signed-off-by: Russell King (Oracle) --- arch/arm/include/asm/pgtable-nommu.h | 6 ------ arch/arm/include/asm/pgtable.h | 16 +++++++++------- arch/arm/mm/nommu.c | 19 +++++++++++++++++++ 3 files changed, 28 insertions(+), 13 deletions(-) diff --git a/arch/arm/include/asm/pgtable-nommu.h b/arch/arm/include/asm/pgtable-nommu.h index d16aba48fa0a..090011394477 100644 --- a/arch/arm/include/asm/pgtable-nommu.h +++ b/arch/arm/include/asm/pgtable-nommu.h @@ -44,12 +44,6 @@ typedef pte_t *pte_addr_t; -/* - * ZERO_PAGE is a global shared page that is always zero: used - * for zero-mapped memory areas etc.. - */ -#define ZERO_PAGE(vaddr) (virt_to_page(0)) - /* * Mark the prot value as uncacheable and unbufferable. */ diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index 78a532068fec..ef48a55e9af8 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -10,6 +10,15 @@ #include #include +#ifndef __ASSEMBLY__ +/* + * ZERO_PAGE is a global shared page that is always zero: used + * for zero-mapped memory areas etc.. + */ +extern struct page *empty_zero_page; +#define ZERO_PAGE(vaddr) (empty_zero_page) +#endif + #ifndef CONFIG_MMU #include @@ -139,13 +148,6 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, */ #ifndef __ASSEMBLY__ -/* - * ZERO_PAGE is a global shared page that is always zero: used - * for zero-mapped memory areas etc.. - */ -extern struct page *empty_zero_page; -#define ZERO_PAGE(vaddr) (empty_zero_page) - extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c index c42debaded95..c1494a4dee25 100644 --- a/arch/arm/mm/nommu.c +++ b/arch/arm/mm/nommu.c @@ -26,6 +26,13 @@ unsigned long vectors_base; +/* + * empty_zero_page is a special page that is used for + * zero-initialized data and COW. + */ +struct page *empty_zero_page; +EXPORT_SYMBOL(empty_zero_page); + #ifdef CONFIG_ARM_MPU struct mpu_rgn_info mpu_rgn_info; #endif @@ -148,9 +155,21 @@ void __init adjust_lowmem_bounds(void) */ void __init paging_init(const struct machine_desc *mdesc) { + void *zero_page; + early_trap_init((void *)vectors_base); mpu_setup(); + + /* allocate the zero page. */ + zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE); + if (!zero_page) + panic("%s: Failed to allocate %lu bytes align=0x%lx\n", + __func__, PAGE_SIZE, PAGE_SIZE); + bootmem_init(); + + empty_zero_page = virt_to_page(zero_page); + flush_dcache_page(empty_zero_page); } /* -- cgit