On 2017/3/18 4:27, Dave Anderson wrote:
>
> ----- Original Message -----
>> On 2017/3/17 22:25, Dave Anderson wrote:
>>> ----- Original Message -----
>>>> However, that is why I am interested in your live system initialization
>>>> of kimage_voffset -- for live system access using /dev/mem, /proc/kcore,
>>>> or an older version of the /dev/crash driver that did not have the ioctl()
>>>> to read kimage_voffset. But, in order to do that, arm64_calc_kimage_voffset()
>>>> needs to be able to handle all /proc/iomem cases to correctly calculate
>>>> PHYS_OFFSET.
>>> Or better stated, your arm64_calc_kimage_voffset() needs to be able to handle all
>>> /proc/iomem cases to correctly calculate kimage_voffset. Because on the 4.8
>>> kernel, it does not work.
>> Dave,
>>
>> Sorry for my misunderstanding of PHYS_OFFSET, actually kimage_voffset
>> is the offset between kernel virtual address and physical address. So,
>> to calculate it need find out which physical address is mapping to
>> VA_START, not PHYS_OFFSET.
>>
>> Please check patch v5, it should be OK for live system.
>>
>> Thanks,
>> Yueyi
>
> Yueyi,
>
> Yes, thanks, this patch does select the correct "offset" for
> use by your calculation. On both the 4.8 and 4.10 kernels,
> the System RAM segment at 0x4000200000 is selected.
>
> However, I wonder if it would be simpler to just select the
> System RAM segment that *contains* the "Kernel code" segment,
> which would follow it in /proc/iomem:
>
> 4.8 kernel:
>
> 4000000000-40001fffff : System RAM
> 4000200000-43fa59ffff : System RAM
> 4000280000-4000c7ffff : Kernel code
> 4000d90000-400166ffff : Kernel data
> 43fa5a0000-43fa9dffff : System RAM
> 43fa9e0000-43ff99ffff : System RAM
> 43ff9a0000-43ff9affff : System RAM
> 43ff9b0000-43ff9bffff : System RAM
> 43ff9c0000-43ff9effff : System RAM
> 43ff9f0000-43ffffffff : System RAM
>
> 4.10 kernel:
>
> 4000000000-40001fffff : reserved
> 4000200000-4001ffffff : System RAM
> 4000280000-4000ccffff : Kernel code
> 4000e00000-40016effff : Kernel data
> 40023b0000-4ff733ffff : System RAM
> 4ff7340000-4ff77cffff : reserved
> 4ff77d0000-4ff792ffff : System RAM
> 4ff7930000-4ff7e7ffff : reserved
> 4ff7e80000-4ff7e8ffff : System RAM
> 4ff7e90000-4ff7efffff : reserved
> 4ff7f10000-4ff800ffff : reserved
> 4ff8010000-4fffffffff : System RAM
>
> In other words, just walk through the /proc/iomem entries, saving
> the System RAM start address as you go. Then when "Kernel code" is
> found, use the last RAM start address.
>
> And a couple other things...
>
> For backwards compatibility (i.e., kernels without kimage_voffset),
> the call from arm64_init() should be conditional like this:
>
> if (machdep->flags & NEW_VMEMMAP)
> arm64_calc_kimage_voffset();
>
> And for live systems without /dev/crash, it wouldn't be necessary to
> add "--kaslr=0" to the command line if arm64_calc_kimage_voffset() started
> something like this:
>
> static void
> arm64_calc_kimage_voffset(void)
> {
> struct machine_specific *ms = machdep->machspec;
> ulong offset;
>
> if (ms->kimage_voffset) /* vmcoreinfo, --machdep override, or ioctl */
> return;
>
> if (DUMPFILE()) {
> if (!(kt->flags2 & KASLR) || !(kt->flags & RELOC_SET))
> return;
> }
> ...
>
> What do you think?
>
> Thanks,
> Dave
>
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Agreed, I have made change as your recommendation. For NEW_VMEMMAP,
always calculate kimage_voffset if it not be given.
Thanks,
Yueyi
From 47060ef9f16ba64584f0a9222eba9271d34f9031 Mon Sep 17 00:00:00 2001
From: Yueyi Li <liyueyi@xxxxxxxx>
Date: Tue, 14 Mar 2017 21:25:21 +0800
Subject: [PATCH] [ARM64][patch] Auto calculate kimage_voffset.
For some use case such as VMCOREINFO or /dev/crash is not support,
kimage_voffset can not be read directly, then try to calculate it.
---
arm64.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/arm64.c b/arm64.c
index 6eaf96d..01edc36 100644
--- a/arm64.c
+++ b/arm64.c
@@ -27,6 +27,7 @@
static struct machine_specific arm64_machine_specific = { 0 };
static int arm64_verify_symbol(const char *, ulong, char);
static void arm64_parse_cmdline_args(void);
+static void arm64_calc_kimage_voffset(void);
static void arm64_calc_phys_offset(void);
static void arm64_calc_virtual_memory_ranges(void);
static int arm64_kdump_phys_base(ulong *);
@@ -216,6 +217,8 @@ arm64_init(int when)
+ ARM64_MODULES_VSIZE -1;
ms->vmalloc_start_addr = ms->modules_end + 1;
+
+ arm64_calc_kimage_voffset();
} else {
ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
ms->modules_end = ARM64_PAGE_OFFSET - 1;
@@ -735,6 +738,68 @@ arm64_parse_cmdline_args(void)
}
}
+static void
+arm64_calc_kimage_voffset(void)
+{
+ struct machine_specific *ms = machdep->machspec;
+ ulong phys_addr;
+
+ if (ms->kimage_voffset) /* vmcoreinfo or --machdep override */
+ return;
+
+ if(ACTIVE()){
+ char buf[BUFSIZE];
+ char *p1;
+ int errflag;
+ FILE *iomem;
+
+ if ((iomem = fopen("/proc/iomem", "r")) == NULL)
+ return;
+
+ errflag = 1;
+ while (fgets(buf, BUFSIZE, iomem)) {
+ if(strstr(buf, ": Kernel code")) {
+ errflag = 0;
+ break;
+ }
+ if (strstr(buf, ": System RAM")) {
+ clean_line(buf);
+
+ if (!(p1 = strstr(buf, "-")))
+ continue;
+
+ *p1 = NULLCHAR;
+
+ phys_addr = htol(buf, RETURN_ON_ERROR | QUIET, NULL);
+ if (BADADDR == phys_addr)
+ continue;
+ }
+ }
+ fclose(iomem);
+
+ if (errflag)
+ return;
+
+ }else if (DISKDUMP_DUMPFILE())
+ return;
+ else if (KDUMP_DUMPFILE())
+ arm_kdump_phys_base(&phys_addr); /*Get start address of first memory block*/
+ else{
+ error(WARNING,
+ "kimage_voffset cannot be determined from the dumpfile.\n");
+ error(CONT,
+ "Using default value of 0. If this is not correct, then try\n");
+ error(CONT,
+ "using the command line option: --machdep kimage_voffset=<addr>\n");
+ return;
+ }
+
+ ms->kimage_voffset = ms->vmalloc_start_addr - phys_addr;
+
+ if ((kt->flags2 & KASLR) && (kt->flags & RELOC_SET))
+ ms->kimage_voffset += (kt->relocate * -1);
+
+}
static void
arm64_calc_phys_offset(void)
--
1.9.1
--
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