arm64 kexec hang
panand at redhat.com
Mon Mar 30 07:38:27 PDT 2015
On Monday 30 March 2015 05:56 PM, Pratyush Anand wrote:
> Hi Geoff,
> On Saturday 28 March 2015 02:41 AM, Pratyush Anand wrote:
>> Hi Geoff,
>> On Friday 27 March 2015 10:53 PM, Geoff Levand wrote:
>>> Hi Pratyush,
>>> On Wed, 2015-03-25 at 15:55 +0530, Pratyush Anand wrote:
>>>> So with following changes kexec load seems to complete without any
>>>> error. However, kexec reboot does not work yet, Nothing after bye
>>>> message :( (1st kernel booted with maxcpus=1)
>>> 'Bye!' doesn't mean much, other than the first kernel has
>>> almost shutdown. I recommend for debugging you either define
>>> ARM64_DEBUG_PORT for the kexec-tools build, or have a suitable
>>> earlyprintk= on the kernel command line. See the read_sink()
>>> routine in kexec-arm64.c.
> Problem seems to be related to compilation of purgatory code.
> For example see here:
> 70 0000000000000120 <purgatory>:
> 71 120: a9bf7bfd stp x29, x30, [sp,#-16]!
> 72 124: 910003fd mov x29, sp
> 73 128: 58000100 ldr x0, 148 <purgatory+0x28>
> 74 12c: 94000000 bl 544 <printf>
> So, when it executes instruction at address 0x128 in above code, it does
> not contain correct address of data where "I'm in purgatory" is located.
> It seems that code has been compiled as 32 bit.
> PC: 0x400415012c , PSTATE: 0x400003c9
> (gdb) monitor reg x0
> x0 (/64): 0x00000000041568F8
> (gdb) monitor mdw 0x00000000041568F8 4
> 0x41568f8: fffefffe fffefffe fffefffe fffefffe : ................
> The buffer location passed to printf is not correct.
> Similarly, even if ARM64_DEBUG_PORT is programmed with correct UART TX
> register, arm64_sink is not modified correctly when elf_rel_set_symbol
> is called.
> So correct data is at 0x00000040041568F8 and not 0x00000000041568F8
> (gdb) monitor mdw 0x00000040041568F8 4
> 0x40041568f8: 206d2749 70206e69 61677275 79726f74 : I'm in purgatory
> should n't the pc relative instruction like adrp be generated instead of
> What does -mcmodel=large cflag do? May be it is causing to generate such
Following changes allows purgatory to execute.
diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 8df66f5c8273..4365bb4087ad 100644
@@ -993,8 +993,8 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr,
unsigned long r_type,
# define R_AARCH64_CALL26 283
- uint32_t *location = (uint32_t *)ptr;
- uint32_t data = *location;
+ uint64_t *location = (uint64_t *)ptr;
+ uint64_t data = *location;
const char *type = NULL;
@@ -1026,7 +1026,7 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr,
unsigned long r_type,
- dbgprintf("%s: %s %x->%x\n", __func__, type, data, *location);
+ dbgprintf("%s: %s %lx->%lx\n", __func__, type, data, *location);
So I get following and then nothing..
[ 162.087569] Bye!
I'm in purgatory
purgatory: kernel_entry: 0000004000280000
Hopefully, I will be able to debug it further.will come back.
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