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Date: Mon, 15 Apr 2019 07:55:18 +0300
From: Mike Rapoport <rppt@...ux.ibm.com>
To: Chen Zhou <chenzhou10@...wei.com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
ebiederm@...ssion.com, catalin.marinas@....com,
will.deacon@....com, akpm@...ux-foundation.org,
ard.biesheuvel@...aro.org, horms@...ge.net.au,
takahiro.akashi@...aro.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
linux-mm@...ck.org, wangkefeng.wang@...wei.com
Subject: Re: [PATCH v3 3/4] arm64: kdump: support more than one crash kernel
regions
On Mon, Apr 15, 2019 at 10:27:30AM +0800, Chen Zhou wrote:
> Hi Mike,
>
> On 2019/4/14 20:13, Mike Rapoport wrote:
> > Hi,
> >
> > On Tue, Apr 09, 2019 at 06:28:18PM +0800, Chen Zhou wrote:
> >> After commit (arm64: kdump: support reserving crashkernel above 4G),
> >> there may be two crash kernel regions, one is below 4G, the other is
> >> above 4G.
> >>
> >> Crash dump kernel reads more than one crash kernel regions via a dtb
> >> property under node /chosen,
> >> linux,usable-memory-range = <BASE1 SIZE1 [BASE2 SIZE2]>
> >
> > Somehow I've missed that previously, but how is this supposed to work on
> > EFI systems?
>
> Whatever the way in which the systems work, there is FDT pointer(__fdt_pointer)
> in arm64 kernel and file /sys/firmware/fdt will be created in late_initcall.
>
> Kexec-tools read and update file /sys/firmware/fdt in EFI systems to support kdump to
> boot capture kernel.
>
> For supporting more than one crash kernel regions, kexec-tools make changes accordingly.
> Details are in below:
> http://lists.infradead.org/pipermail/kexec/2019-April/022792.html
Thanks for the clarification!
> Thanks,
> Chen Zhou
>
> >
> >> Signed-off-by: Chen Zhou <chenzhou10@...wei.com>
> >> ---
> >> arch/arm64/mm/init.c | 66 ++++++++++++++++++++++++++++++++++++++++--------
> >> include/linux/memblock.h | 6 +++++
> >> mm/memblock.c | 7 ++---
> >> 3 files changed, 66 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> >> index 3bebddf..0f18665 100644
> >> --- a/arch/arm64/mm/init.c
> >> +++ b/arch/arm64/mm/init.c
> >> @@ -65,6 +65,11 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init;
> >>
> >> #ifdef CONFIG_KEXEC_CORE
> >>
> >> +/* at most two crash kernel regions, low_region and high_region */
> >> +#define CRASH_MAX_USABLE_RANGES 2
> >> +#define LOW_REGION_IDX 0
> >> +#define HIGH_REGION_IDX 1
> >> +
> >> /*
> >> * reserve_crashkernel() - reserves memory for crash kernel
> >> *
> >> @@ -297,8 +302,8 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
> >> const char *uname, int depth, void *data)
> >> {
> >> struct memblock_region *usablemem = data;
> >> - const __be32 *reg;
> >> - int len;
> >> + const __be32 *reg, *endp;
> >> + int len, nr = 0;
> >>
> >> if (depth != 1 || strcmp(uname, "chosen") != 0)
> >> return 0;
> >> @@ -307,22 +312,63 @@ static int __init early_init_dt_scan_usablemem(unsigned long node,
> >> if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
> >> return 1;
> >>
> >> - usablemem->base = dt_mem_next_cell(dt_root_addr_cells, ®);
> >> - usablemem->size = dt_mem_next_cell(dt_root_size_cells, ®);
> >> + endp = reg + (len / sizeof(__be32));
> >> + while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> >> + usablemem[nr].base = dt_mem_next_cell(dt_root_addr_cells, ®);
> >> + usablemem[nr].size = dt_mem_next_cell(dt_root_size_cells, ®);
> >> +
> >> + if (++nr >= CRASH_MAX_USABLE_RANGES)
> >> + break;
> >> + }
> >>
> >> return 1;
> >> }
> >>
> >> static void __init fdt_enforce_memory_region(void)
> >> {
> >> - struct memblock_region reg = {
> >> - .size = 0,
> >> - };
> >> + int i, cnt = 0;
> >> + struct memblock_region regs[CRASH_MAX_USABLE_RANGES];
> >> +
> >> + memset(regs, 0, sizeof(regs));
> >> + of_scan_flat_dt(early_init_dt_scan_usablemem, regs);
> >> +
> >> + for (i = 0; i < CRASH_MAX_USABLE_RANGES; i++)
> >> + if (regs[i].size)
> >> + cnt++;
> >> + else
> >> + break;
> >> +
> >> + if (cnt - 1 == LOW_REGION_IDX)
> >> + memblock_cap_memory_range(regs[LOW_REGION_IDX].base,
> >> + regs[LOW_REGION_IDX].size);
> >> + else if (cnt - 1 == HIGH_REGION_IDX) {
> >> + /*
> >> + * Two crash kernel regions, cap the memory range
> >> + * [regs[LOW_REGION_IDX].base, regs[HIGH_REGION_IDX].end]
> >> + * and then remove the memory range in the middle.
> >> + */
> >> + int start_rgn, end_rgn, i, ret;
> >> + phys_addr_t mid_base, mid_size;
> >> +
> >> + mid_base = regs[LOW_REGION_IDX].base + regs[LOW_REGION_IDX].size;
> >> + mid_size = regs[HIGH_REGION_IDX].base - mid_base;
> >> + ret = memblock_isolate_range(&memblock.memory, mid_base,
> >> + mid_size, &start_rgn, &end_rgn);
> >>
> >> - of_scan_flat_dt(early_init_dt_scan_usablemem, ®);
> >> + if (ret)
> >> + return;
> >>
> >> - if (reg.size)
> >> - memblock_cap_memory_range(reg.base, reg.size);
> >> + memblock_cap_memory_range(regs[LOW_REGION_IDX].base,
> >> + regs[HIGH_REGION_IDX].base -
> >> + regs[LOW_REGION_IDX].base +
> >> + regs[HIGH_REGION_IDX].size);
> >> + for (i = end_rgn - 1; i >= start_rgn; i--) {
> >> + if (!memblock_is_nomap(&memblock.memory.regions[i]))
> >> + memblock_remove_region(&memblock.memory, i);
> >> + }
> >> + memblock_remove_range(&memblock.reserved, mid_base,
> >> + mid_base + mid_size);
> >> + }
> >> }
> >>
> >> void __init arm64_memblock_init(void)
> >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> >> index 294d5d8..787d252 100644
> >> --- a/include/linux/memblock.h
> >> +++ b/include/linux/memblock.h
> >> @@ -110,9 +110,15 @@ void memblock_discard(void);
> >>
> >> phys_addr_t memblock_find_in_range(phys_addr_t start, phys_addr_t end,
> >> phys_addr_t size, phys_addr_t align);
> >> +void memblock_remove_region(struct memblock_type *type, unsigned long r);
> >> void memblock_allow_resize(void);
> >> int memblock_add_node(phys_addr_t base, phys_addr_t size, int nid);
> >> int memblock_add(phys_addr_t base, phys_addr_t size);
> >> +int memblock_isolate_range(struct memblock_type *type,
> >> + phys_addr_t base, phys_addr_t size,
> >> + int *start_rgn, int *end_rgn);
> >> +int memblock_remove_range(struct memblock_type *type,
> >> + phys_addr_t base, phys_addr_t size);
> >> int memblock_remove(phys_addr_t base, phys_addr_t size);
> >> int memblock_free(phys_addr_t base, phys_addr_t size);
> >> int memblock_reserve(phys_addr_t base, phys_addr_t size);
> >> diff --git a/mm/memblock.c b/mm/memblock.c
> >> index e7665cf..1846e2d 100644
> >> --- a/mm/memblock.c
> >> +++ b/mm/memblock.c
> >> @@ -357,7 +357,8 @@ phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
> >> return ret;
> >> }
> >>
> >> -static void __init_memblock memblock_remove_region(struct memblock_type *type, unsigned long r)
> >> +void __init_memblock memblock_remove_region(struct memblock_type *type,
> >> + unsigned long r)
> >> {
> >> type->total_size -= type->regions[r].size;
> >> memmove(&type->regions[r], &type->regions[r + 1],
> >> @@ -724,7 +725,7 @@ int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
> >> * Return:
> >> * 0 on success, -errno on failure.
> >> */
> >> -static int __init_memblock memblock_isolate_range(struct memblock_type *type,
> >> +int __init_memblock memblock_isolate_range(struct memblock_type *type,
> >> phys_addr_t base, phys_addr_t size,
> >> int *start_rgn, int *end_rgn)
> >> {
> >> @@ -784,7 +785,7 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
> >> return 0;
> >> }
> >>
> >> -static int __init_memblock memblock_remove_range(struct memblock_type *type,
> >> +int __init_memblock memblock_remove_range(struct memblock_type *type,
> >> phys_addr_t base, phys_addr_t size)
> >> {
> >> int start_rgn, end_rgn;
> >> --
> >> 2.7.4
> >>
> >
>
--
Sincerely yours,
Mike.
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