Re: [PATCH v17 05/10] x86: kdump: move reserve_crashkernel[_low]() into crash_core.c

john.p.donnelly
2021-12-13T14:30:51Z

On 12/10/21 12:55 AM, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10@huawei.com>
>
> Make the functions reserve_crashkernel[_low]() as generic. Since
> reserve_crashkernel[_low]() implementations are quite similar on other
> architectures as well, we can have more users of this later.
>
> So have CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL in arch/Kconfig and
> select this by X86.
>
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> Tested-by: John Donnelly <John.p.donnelly@oracle.com>
> Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>

Acked-by: John Donnelly <john.p.donnelly@oracle.com>
> ---
> arch/Kconfig | 3 +
> arch/x86/Kconfig | 2 +
> arch/x86/include/asm/elf.h | 3 +
> arch/x86/include/asm/kexec.h | 28 ++++++-
> arch/x86/kernel/setup.c | 143 +-------------------------------
> include/linux/crash_core.h | 3 +
> include/linux/kexec.h | 2 -
> kernel/crash_core.c | 156 +++++++++++++++++++++++++++++++++++
> kernel/kexec_core.c | 17 ----
> 9 files changed, 194 insertions(+), 163 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index d3c4ab249e9c275..7bdb32c41985dc5 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -24,6 +24,9 @@ config KEXEC_ELF
> config HAVE_IMA_KEXEC
> bool
>
> +config ARCH_WANT_RESERVE_CRASH_KERNEL
> + bool
> +
> config SET_FS
> bool
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 5c2ccb85f2efb86..bd78ed8193079b9 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -12,6 +12,7 @@ config X86_32
> depends on !64BIT
> # Options that are inherently 32-bit kernel only:
> select ARCH_WANT_IPC_PARSE_VERSION
> + select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
> select CLKSRC_I8253
> select CLONE_BACKWARDS
> select GENERIC_VDSO_32
> @@ -28,6 +29,7 @@ config X86_64
> select ARCH_HAS_GIGANTIC_PAGE
> select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
> select ARCH_USE_CMPXCHG_LOCKREF
> + select ARCH_WANT_RESERVE_CRASH_KERNEL if KEXEC_CORE
> select HAVE_ARCH_SOFT_DIRTY
> select MODULES_USE_ELF_RELA
> select NEED_DMA_MAP_STATE
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index 29fea180a6658e8..7a6c36cff8331f5 100644
> --- a/arch/x86/include/asm/elf.h
> +++ b/arch/x86/include/asm/elf.h
> @@ -94,6 +94,9 @@ extern unsigned int vdso32_enabled;
>
> #define elf_check_arch(x) elf_check_arch_ia32(x)
>
> +/* We can also handle crash dumps from 64 bit kernel. */
> +# define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)
> +
> /* SVR4/i386 ABI (pages 3-31, 3-32) says that when the program starts %edx
> contains a pointer to a function which might be registered using `atexit'.
> This provides a mean for the dynamic linker to call DT_FINI functions for
> diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
> index 3a22e65262aa70b..3ff38a1353a2b86 100644
> --- a/arch/x86/include/asm/kexec.h
> +++ b/arch/x86/include/asm/kexec.h
> @@ -21,6 +21,27 @@
> /* 16M alignment for crash kernel regions */
> #define CRASH_ALIGN SZ_16M
>
> +/*
> + * Keep the crash kernel below this limit.
> + *
> + * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> + * due to mapping restrictions.
> + *
> + * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> + * the upper limit of system RAM in 4-level paging mode. Since the kdump
> + * jump could be from 5-level paging to 4-level paging, the jump will fail if
> + * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> + * no good way to detect the paging mode of the target kernel which will be
> + * loaded for dumping.
> + */
> +#ifdef CONFIG_X86_32
> +# define CRASH_ADDR_LOW_MAX SZ_512M
> +# define CRASH_ADDR_HIGH_MAX SZ_512M
> +#else
> +# define CRASH_ADDR_LOW_MAX SZ_4G
> +# define CRASH_ADDR_HIGH_MAX SZ_64T
> +#endif
> +
> #ifndef __ASSEMBLY__
>
> #include <linux/string.h>
> @@ -51,9 +72,6 @@ struct kimage;
>
> /* The native architecture */
> # define KEXEC_ARCH KEXEC_ARCH_386
> -
> -/* We can also handle crash dumps from 64 bit kernel. */
> -# define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)
> #else
> /* Maximum physical address we can use pages from */
> # define KEXEC_SOURCE_MEMORY_LIMIT (MAXMEM-1)
> @@ -195,6 +213,10 @@ typedef void crash_vmclear_fn(void);
> extern crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss;
> extern void kdump_nmi_shootdown_cpus(void);
>
> +#ifdef CONFIG_KEXEC_CORE
> +extern void __init reserve_crashkernel(void);
> +#endif
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_X86_KEXEC_H */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 7ae00716a208f82..5519baa7f4b964e 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -39,6 +39,7 @@
> #include <asm/io_apic.h>
> #include <asm/kasan.h>
> #include <asm/kaslr.h>
> +#include <asm/kexec.h>
> #include <asm/mce.h>
> #include <asm/mtrr.h>
> #include <asm/realmode.h>
> @@ -386,147 +387,7 @@ static void __init memblock_x86_reserve_range_setup_data(void)
> }
> }
>
> -/*
> - * --------- Crashkernel reservation ------------------------------
> - */
> -
> -#ifdef CONFIG_KEXEC_CORE
> -
> -/*
> - * Keep the crash kernel below this limit.
> - *
> - * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> - * due to mapping restrictions.
> - *
> - * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> - * the upper limit of system RAM in 4-level paging mode. Since the kdump
> - * jump could be from 5-level paging to 4-level paging, the jump will fail if
> - * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> - * no good way to detect the paging mode of the target kernel which will be
> - * loaded for dumping.
> - */
> -#ifdef CONFIG_X86_32
> -# define CRASH_ADDR_LOW_MAX SZ_512M
> -# define CRASH_ADDR_HIGH_MAX SZ_512M
> -#else
> -# define CRASH_ADDR_LOW_MAX SZ_4G
> -# define CRASH_ADDR_HIGH_MAX SZ_64T
> -#endif
> -
> -static int __init reserve_crashkernel_low(void)
> -{
> -#ifdef CONFIG_X86_64
> - unsigned long long base, low_base = 0, low_size = 0;
> - unsigned long low_mem_limit;
> - int ret;
> -
> - low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
> -
> - /* crashkernel=Y,low */
> - ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
> - if (ret) {
> - /*
> - * two parts from kernel/dma/swiotlb.c:
> - * -swiotlb size: user-specified with swiotlb= or default.
> - *
> - * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> - * to 8M for other buffers that may need to stay low too. Also
> - * make sure we allocate enough extra low memory so that we
> - * don't run out of DMA buffers for 32-bit devices.
> - */
> - low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> - } else {
> - /* passed with crashkernel=0,low ? */
> - if (!low_size)
> - return 0;
> - }
> -
> - low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, CRASH_ALIGN,
> - CRASH_ADDR_LOW_MAX);
> - if (!low_base) {
> - pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> - (unsigned long)(low_size >> 20));
> - return -ENOMEM;
> - }
> -
> - pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
> - (unsigned long)(low_size >> 20),
> - (unsigned long)(low_base >> 20),
> - (unsigned long)(low_mem_limit >> 20));
> -
> - crashk_low_res.start = low_base;
> - crashk_low_res.end = low_base + low_size - 1;
> -#endif
> - return 0;
> -}
> -
> -static void __init reserve_crashkernel(void)
> -{
> - unsigned long long crash_size, crash_base, total_mem;
> - bool high = false;
> - int ret;
> -
> - total_mem = memblock_phys_mem_size();
> -
> - /* crashkernel=XM */
> - ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
> - if (ret != 0 || crash_size <= 0) {
> - /* crashkernel=X,high */
> - ret = parse_crashkernel_high(boot_command_line, total_mem,
> - &crash_size, &crash_base);
> - if (ret != 0 || crash_size <= 0)
> - return;
> - high = true;
> - }
> -
> - /* 0 means: find the address automatically */
> - if (!crash_base) {
> - /*
> - * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> - * crashkernel=x,high reserves memory over CRASH_ADDR_LOW_MAX,
> - * also allocates 256M extra low memory for DMA buffers
> - * and swiotlb.
> - * But the extra memory is not required for all machines.
> - * So try low memory first and fall back to high memory
> - * unless "crashkernel=size[KMG],high" is specified.
> - */
> - if (!high)
> - crash_base = memblock_phys_alloc_range(crash_size,
> - CRASH_ALIGN, CRASH_ALIGN,
> - CRASH_ADDR_LOW_MAX);
> - if (!crash_base)
> - crash_base = memblock_phys_alloc_range(crash_size,
> - CRASH_ALIGN, CRASH_ALIGN,
> - CRASH_ADDR_HIGH_MAX);
> - if (!crash_base) {
> - pr_info("crashkernel reservation failed - No suitable area found.\n");
> - return;
> - }
> - } else {
> - unsigned long long start;
> -
> - start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> - crash_base + crash_size);
> - if (start != crash_base) {
> - pr_info("crashkernel reservation failed - memory is in use.\n");
> - return;
> - }
> - }
> -
> - if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
> - memblock_phys_free(crash_base, crash_size);
> - return;
> - }
> -
> - pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> - (unsigned long)(crash_size >> 20),
> - (unsigned long)(crash_base >> 20),
> - (unsigned long)(total_mem >> 20));
> -
> - crashk_res.start = crash_base;
> - crashk_res.end = crash_base + crash_size - 1;
> -}
> -#else
> +#ifndef CONFIG_KEXEC_CORE
> static void __init reserve_crashkernel(void)
> {
> }
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index de62a722431e7db..f6b99da4ed08ecf 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -73,6 +73,9 @@ extern unsigned char *vmcoreinfo_data;
> extern size_t vmcoreinfo_size;
> extern u32 *vmcoreinfo_note;
>
> +extern struct resource crashk_res;
> +extern struct resource crashk_low_res;
> +
> Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> void *data, size_t data_len);
> void final_note(Elf_Word *buf);
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 0c994ae37729e1e..cd744d962f6f417 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -352,8 +352,6 @@ extern int kexec_load_disabled;
>
> /* Location of a reserved region to hold the crash kernel.
> */
> -extern struct resource crashk_res;
> -extern struct resource crashk_low_res;
> extern note_buf_t __percpu *crash_notes;
>
> /* flag to track if kexec reboot is in progress */
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index eb53f5ec62c900f..b23cfc0ca8905fd 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -8,6 +8,12 @@
> #include <linux/crash_core.h>
> #include <linux/utsname.h>
> #include <linux/vmalloc.h>
> +#include <linux/memblock.h>
> +#include <linux/swiotlb.h>
> +
> +#ifdef CONFIG_KEXEC_CORE
> +#include <asm/kexec.h>
> +#endif
>
> #include <asm/page.h>
> #include <asm/sections.h>
> @@ -22,6 +28,22 @@ u32 *vmcoreinfo_note;
> /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
> static unsigned char *vmcoreinfo_data_safecopy;
>
> +/* Location of the reserved area for the crash kernel */
> +struct resource crashk_res = {
> + .name = "Crash kernel",
> + .start = 0,
> + .end = 0,
> + .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> + .desc = IORES_DESC_CRASH_KERNEL
> +};
> +struct resource crashk_low_res = {
> + .name = "Crash kernel",
> + .start = 0,
> + .end = 0,
> + .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> + .desc = IORES_DESC_CRASH_KERNEL
> +};
> +
> /*
> * parsing the "crashkernel" commandline
> *
> @@ -295,6 +317,140 @@ int __init parse_crashkernel_low(char *cmdline,
> "crashkernel=", suffix_tbl[SUFFIX_LOW]);
> }
>
> +/*
> + * --------- Crashkernel reservation ------------------------------
> + */
> +
> +#ifdef CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL
> +static int __init reserve_crashkernel_low(void)
> +{
> +#ifdef CONFIG_64BIT
> + unsigned long long base, low_base = 0, low_size = 0;
> + unsigned long low_mem_limit;
> + int ret;
> +
> + low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
> +
> + /* crashkernel=Y,low */
> + ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
> + if (ret) {
> + /*
> + * two parts from kernel/dma/swiotlb.c:
> + * -swiotlb size: user-specified with swiotlb= or default.
> + *
> + * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> + * to 8M for other buffers that may need to stay low too. Also
> + * make sure we allocate enough extra low memory so that we
> + * don't run out of DMA buffers for 32-bit devices.
> + */
> + low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> + } else {
> + /* passed with crashkernel=0,low ? */
> + if (!low_size)
> + return 0;
> + }
> +
> + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, CRASH_ALIGN,
> + CRASH_ADDR_LOW_MAX);
> + if (!low_base) {
> + pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> + (unsigned long)(low_size >> 20));
> + return -ENOMEM;
> + }
> +
> + pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
> + (unsigned long)(low_size >> 20),
> + (unsigned long)(low_base >> 20),
> + (unsigned long)(low_mem_limit >> 20));
> +
> + crashk_low_res.start = low_base;
> + crashk_low_res.end = low_base + low_size - 1;
> +#endif
> + return 0;
> +}
> +
> +/*
> + * reserve_crashkernel() - reserves memory for crash kernel
> + *
> + * This function reserves memory area given in "crashkernel=" kernel command
> + * line parameter. The memory reserved is used by dump capture kernel when
> + * primary kernel is crashing.
> + */
> +void __init reserve_crashkernel(void)
> +{
> + unsigned long long crash_size, crash_base, total_mem;
> + bool high = false;
> + int ret;
> +
> + total_mem = memblock_phys_mem_size();
> +
> + /* crashkernel=XM */
> + ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
> + if (ret != 0 || crash_size <= 0) {
> + /* crashkernel=X,high */
> + ret = parse_crashkernel_high(boot_command_line, total_mem,
> + &crash_size, &crash_base);
> + if (ret != 0 || crash_size <= 0)
> + return;
> + high = true;
> + }
> +
> + /* 0 means: find the address automatically */
> + if (!crash_base) {
> + /*
> + * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> + * crashkernel=x,high reserves memory over CRASH_ADDR_LOW_MAX,
> + * also allocates 256M extra low memory for DMA buffers
> + * and swiotlb.
> + * But the extra memory is not required for all machines.
> + * So try low memory first and fall back to high memory
> + * unless "crashkernel=size[KMG],high" is specified.
> + */
> + if (!high)
> + crash_base = memblock_phys_alloc_range(crash_size,
> + CRASH_ALIGN, CRASH_ALIGN,
> + CRASH_ADDR_LOW_MAX);
> + if (!crash_base)
> + crash_base = memblock_phys_alloc_range(crash_size,
> + CRASH_ALIGN, CRASH_ALIGN,
> + CRASH_ADDR_HIGH_MAX);
> + if (!crash_base) {
> + pr_info("crashkernel reservation failed - No suitable area found.\n");
> + return;
> + }
> + } else {
> + /* User specifies base address explicitly. */
> + unsigned long long start;
> +
> + if (!IS_ALIGNED(crash_base, CRASH_ALIGN)) {
> + pr_warn("cannot reserve crashkernel: base address is not %ldMB aligned\n",
> + (unsigned long)CRASH_ALIGN >> 20);
> + return;
> + }
> +
> + start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> + crash_base + crash_size);
> + if (start != crash_base) {
> + pr_info("crashkernel reservation failed - memory is in use.\n");
> + return;
> + }
> + }
> +
> + if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
> + memblock_phys_free(crash_base, crash_size);
> + return;
> + }
> +
> + pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> + (unsigned long)(crash_size >> 20),
> + (unsigned long)(crash_base >> 20),
> + (unsigned long)(total_mem >> 20));
> +
> + crashk_res.start = crash_base;
> + crashk_res.end = crash_base + crash_size - 1;
> +}
> +#endif /* CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL */
> +
> Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> void *data, size_t data_len)
> {
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 5a5d192a89ac307..1e0d4909bbb6b77 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -54,23 +54,6 @@ note_buf_t __percpu *crash_notes;
> /* Flag to indicate we are going to kexec a new kernel */
> bool kexec_in_progress = false;
>
> -
> -/* Location of the reserved area for the crash kernel */
> -struct resource crashk_res = {
> - .name = "Crash kernel",
> - .start = 0,
> - .end = 0,
> - .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> - .desc = IORES_DESC_CRASH_KERNEL
> -};
> -struct resource crashk_low_res = {
> - .name = "Crash kernel",
> - .start = 0,
> - .end = 0,
> - .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
> - .desc = IORES_DESC_CRASH_KERNEL
> -};
> -
> int kexec_should_crash(struct task_struct *p)
> {
> /*