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* [PATCH] arm64, vmcoreinfo : Append 'MAX_USER_VA_BITS' and 'MAX_PHYSMEM_BITS' to vmcoreinfo
@ 2019-01-30 12:23 Bhupesh Sharma
  2019-01-30 15:21 ` James Morse
  2019-01-31  1:48 ` Dave Young
  0 siblings, 2 replies; 29+ messages in thread
From: Bhupesh Sharma @ 2019-01-30 12:23 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: Mark Rutland, ard.biesheuvel, catalin.marinas, bhsharma, kexec,
	Will Deacon, AKASHI Takahiro, James Morse, bhupesh.linux

With ARMv8.2-LVA and LPA architecture extensions, arm64 hardware which
supports these extensions can support upto 52-bit virtual and 52-bit
physical addresses respectively.

Since at the moment we enable the support of these extensions via CONFIG
flags, e.g.
 - LPA via CONFIG_ARM64_PA_BITS_52

there are no clear mechanisms in user-space right now to
deteremine these CONFIG flag values and also determine the PARange and
VARange address values.

User-space tools like 'makedumpfile' and 'crash-utility' can instead
use the 'MAX_USER_VA_BITS' and 'MAX_PHYSMEM_BITS' values to determine
the maximum virtual address and physical address (respectively)
supported by underlying kernel.

A reference 'makedumpfile' implementation which uses this approach to
determining the maximum physical address is available in [0].

[0]. https://github.com/bhupesh-sharma/makedumpfile/blob/52-bit-pa-support-via-vmcore-v1/arch/arm64.c#L490

Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Bhupesh Sharma <bhsharma@redhat.com>
---
 arch/arm64/kernel/crash_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/crash_core.c b/arch/arm64/kernel/crash_core.c
index ca4c3e12d8c5..ad231be5c0d8 100644
--- a/arch/arm64/kernel/crash_core.c
+++ b/arch/arm64/kernel/crash_core.c
@@ -10,6 +10,8 @@
 void arch_crash_save_vmcoreinfo(void)
 {
 	VMCOREINFO_NUMBER(VA_BITS);
+	VMCOREINFO_NUMBER(MAX_USER_VA_BITS);
+	VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
 	/* Please note VMCOREINFO_NUMBER() uses "%d", not "%x" */
 	vmcoreinfo_append_str("NUMBER(kimage_voffset)=0x%llx\n",
 						kimage_voffset);
-- 
2.7.4


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2019-01-30 12:23 [PATCH] arm64, vmcoreinfo : Append 'MAX_USER_VA_BITS' and 'MAX_PHYSMEM_BITS' to vmcoreinfo Bhupesh Sharma
2019-01-30 15:21 ` James Morse
2019-01-30 21:39   ` Bhupesh Sharma
2019-02-04 14:35     ` Bhupesh Sharma
2019-02-04 15:31       ` Robin Murphy
2019-02-12  4:55         ` Bhupesh Sharma
2019-02-12 10:49           ` Robin Murphy
2019-02-04 16:56       ` James Morse
2019-01-31  1:48 ` Dave Young
2019-01-31 10:00   ` Bhupesh Sharma
2019-01-31 14:03   ` Dave Anderson
2019-02-04 16:04   ` Kazuhito Hagio
2019-02-12  5:07     ` Bhupesh Sharma
2019-02-12 10:44       ` Dave Young
2019-02-12 19:59         ` Bhupesh Sharma
2019-02-12 23:03           ` Kazuhito Hagio
2019-02-13 11:15             ` Dave Young
2019-02-13 18:22               ` James Morse
2019-02-13 19:52                 ` Kazuhito Hagio
2019-02-15 17:34                   ` James Morse
2019-02-15 18:01                     ` Bhupesh Sharma
2019-02-18 15:27                       ` Steve Capper
2019-02-21 16:08                         ` Bhupesh Sharma
2019-02-19 20:47                       ` Kazuhito Hagio
2019-02-21 16:20                         ` Bhupesh Sharma
2019-02-21 16:42                           ` Dave Anderson
2019-02-21 19:02                             ` Kazuhito Hagio
2019-03-01  4:01                               ` Bhupesh Sharma
2019-02-14 19:30                 ` Bhupesh Sharma

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