ARM: Don't allow highmem on SMP platforms without h/w TLB ops broadcast
We suffer an unfortunate combination of "features" which makes highmem support on platforms without hardware TLB maintainence broadcast difficult: - we need kmap_high_get() support for DMA cache coherence - this requires kmap_high() to take a spinlock with IRQs disabled - kmap_high() occasionally calls flush_all_zero_pkmaps() to clear out old mappings - flush_all_zero_pkmaps() calls flush_tlb_kernel_range(), which on s/w IPI'd systems eventually calls smp_call_function_many() - smp_call_function_many() must not be called with IRQs disabled: WARNING: at kernel/smp.c:380 smp_call_function_many+0xc4/0x240() Modules linked in: Backtrace: [<c00306f0>] (dump_backtrace+0x0/0x108) from [<c0286e6c>] (dump_stack+0x18/0x1c) r6:c007cd18 r5:c02ff228 r4:0000017c [<c0286e54>] (dump_stack+0x0/0x1c) from [<c0053e08>] (warn_slowpath_common+0x50/0x80) [<c0053db8>] (warn_slowpath_common+0x0/0x80) from [<c0053e50>] (warn_slowpath_null+0x18/0x1c) r7:00000003 r6:00000001 r5:c1ff4000 r4:c035fa34 [<c0053e38>] (warn_slowpath_null+0x0/0x1c) from [<c007cd18>] (smp_call_function_many+0xc4/0x240) [<c007cc54>] (smp_call_function_many+0x0/0x240) from [<c007cec0>] (smp_call_function+0x2c/0x38) [<c007ce94>] (smp_call_function+0x0/0x38) from [<c005980c>] (on_each_cpu+0x1c/0x38) [<c00597f0>] (on_each_cpu+0x0/0x38) from [<c0031788>] (flush_tlb_kernel_range+0x50/0x58) r6:00000001 r5:00000800 r4:c05f3590 [<c0031738>] (flush_tlb_kernel_range+0x0/0x58) from [<c009c600>] (flush_all_zero_pkmaps+0xc0/0xe8) [<c009c540>] (flush_all_zero_pkmaps+0x0/0xe8) from [<c009c6b4>] (kmap_high+0x8c/0x1e0) [<c009c628>] (kmap_high+0x0/0x1e0) from [<c00364a8>] (kmap+0x44/0x5c) [<c0036464>] (kmap+0x0/0x5c) from [<c0109dfc>] (cramfs_readpage+0x3c/0x194) [<c0109dc0>] (cramfs_readpage+0x0/0x194) from [<c0090c14>] (__do_page_cache_readahead+0x1f0/0x290) [<c0090a24>] (__do_page_cache_readahead+0x0/0x290) from [<c0090ce4>] (ra_submit+0x30/0x38) [<c0090cb4>] (ra_submit+0x0/0x38) from [<c0089384>] (filemap_fault+0x3dc/0x438) r4:c1819988 [<c0088fa8>] (filemap_fault+0x0/0x438) from [<c009d21c>] (__do_fault+0x58/0x43c) [<c009d1c4>] (__do_fault+0x0/0x43c) from [<c009e8cc>] (handle_mm_fault+0x104/0x318) [<c009e7c8>] (handle_mm_fault+0x0/0x318) from [<c0033c98>] (do_page_fault+0x188/0x1e4) [<c0033b10>] (do_page_fault+0x0/0x1e4) from [<c0033ddc>] (do_translation_fault+0x7c/0x84) [<c0033d60>] (do_translation_fault+0x0/0x84) from [<c002b474>] (do_DataAbort+0x40/0xa4) r8:c1ff5e20 r7:c0340120 r6:00000805 r5:c1ff5e54 r4:c03400d0 [<c002b434>] (do_DataAbort+0x0/0xa4) from [<c002bcac>] (__dabt_svc+0x4c/0x60) ... So we disable highmem support on these systems. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>hifive-unleashed-5.1
Russell King
parent
9a0f6b4646
commit
e616c59140
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@ -0,0 +1,16 @@
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/*
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* ARM specific SMP header, this contains our implementation
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* details.
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*/
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#ifndef __ASMARM_SMP_PLAT_H
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#define __ASMARM_SMP_PLAT_H
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#include <asm/cputype.h>
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/* all SMP configurations have the extended CPUID registers */
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static inline int tlb_ops_need_broadcast(void)
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{
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return ((read_cpuid_ext(CPUID_EXT_MMFR3) >> 12) & 0xf) < 2;
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}
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#endif
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@ -36,6 +36,7 @@
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#include <asm/tlbflush.h>
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#include <asm/ptrace.h>
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#include <asm/localtimer.h>
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#include <asm/smp_plat.h>
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/*
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* as from 2.5, kernels no longer have an init_tasks structure
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@ -586,12 +587,6 @@ struct tlb_args {
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unsigned long ta_end;
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};
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/* all SMP configurations have the extended CPUID registers */
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static inline int tlb_ops_need_broadcast(void)
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{
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return ((read_cpuid_ext(CPUID_EXT_MMFR3) >> 12) & 0xf) < 2;
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}
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static inline void ipi_flush_tlb_all(void *ignored)
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{
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local_flush_tlb_all();
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@ -21,6 +21,7 @@
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#include <asm/cachetype.h>
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#include <asm/setup.h>
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#include <asm/sizes.h>
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#include <asm/smp_plat.h>
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#include <asm/tlb.h>
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#include <asm/highmem.h>
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@ -709,10 +710,6 @@ static void __init sanity_check_meminfo(void)
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if (meminfo.nr_banks >= NR_BANKS) {
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printk(KERN_CRIT "NR_BANKS too low, "
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"ignoring high memory\n");
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} else if (cache_is_vipt_aliasing()) {
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printk(KERN_CRIT "HIGHMEM is not yet supported "
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"with VIPT aliasing cache, "
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"ignoring high memory\n");
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} else {
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memmove(bank + 1, bank,
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(meminfo.nr_banks - i) * sizeof(*bank));
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@ -756,6 +753,38 @@ static void __init sanity_check_meminfo(void)
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#endif
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j++;
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}
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#ifdef CONFIG_HIGHMEM
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if (highmem) {
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const char *reason = NULL;
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if (cache_is_vipt_aliasing()) {
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/*
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* Interactions between kmap and other mappings
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* make highmem support with aliasing VIPT caches
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* rather difficult.
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*/
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reason = "with VIPT aliasing cache";
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#ifdef CONFIG_SMP
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} else if (tlb_ops_need_broadcast()) {
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/*
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* kmap_high needs to occasionally flush TLB entries,
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* however, if the TLB entries need to be broadcast
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* we may deadlock:
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* kmap_high(irqs off)->flush_all_zero_pkmaps->
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* flush_tlb_kernel_range->smp_call_function_many
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* (must not be called with irqs off)
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*/
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reason = "without hardware TLB ops broadcasting";
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#endif
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}
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if (reason) {
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printk(KERN_CRIT "HIGHMEM is not supported %s, ignoring high memory\n",
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reason);
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while (j > 0 && meminfo.bank[j - 1].highmem)
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j--;
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}
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}
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#endif
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meminfo.nr_banks = j;
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}
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