From: Jarkko Sakkinen <jarkko@kernel.org>
To: Reinette Chatre <reinette.chatre@intel.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Shuah Khan <shuah@kernel.org>,
"open list:INTEL SGX" <linux-sgx@vger.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] selftests/sgx: Use rip relative addressing for encl_stack
Date: Wed, 30 Mar 2022 22:22:43 +0300 [thread overview]
Message-ID: <962cf8bf3544fe3e5d263442bb5ca2e21f25a54b.camel@kernel.org> (raw)
In-Reply-To: <f68d472877b7136c32d8770603a3de38de59c322.camel@kernel.org>
On Wed, 2022-03-30 at 22:03 +0300, Jarkko Sakkinen wrote:
> On Wed, 2022-03-30 at 10:40 -0700, Reinette Chatre wrote:
> > Could you please elaborate how the compiler will fix it up?
>
> Sure.
>
> Here's the disassembly of the RBX version:
>
> [0x000021a9]> pi 1
> lea rax, [rbx + loc.encl_stack]
>
> Here's the same with s/RBX/RIP/:
>
> [0x000021a9]> pi 5
> lea rax, loc.encl_stack
> Compiler will substitute correct offset relative to the RIP,
> well, because it can and it makes sense.
>
> It is treated differently than other registers, e.g. when
> LEA is assembled.
>
> BR, Jarkko
To demonstrate this I did a couple of simple sessions with Rizin
(fork/continuation/something of Radare2):
jarkko@suppilovahvero ~/Downloads (main)> rizin test_encl.rbx.elf
-- Temporally drop the verbosity prefixing the commands with ':'
[0x00002000]> aaa
[x] Analyze all flags starting with sym. and entry0 (aa)
[x] Analyze function calls (aac)
[x] Analyze len bytes of instructions for references (aar)
[x] Check for classes
[x] Type matching analysis for all functions (aaft)
[x] Propagate noreturn information
[x] Use -AA or aaaa to perform additional experimental analysis.
[0x00002000]> /ad lea
0x0000206e # 7: lea rax, [rip + 0xf8b]
0x0000206f # 6: lea eax, [rip + 0xf8b]
0x0000207e # 1: leave
0x000020a1 # 7: lea rcx, [rip + 0xf58]
0x000020a2 # 6: lea ecx, [rip + 0xf58]
0x000020b4 # 1: leave
0x000020ee # 1: leave
0x00002128 # 1: leave
0x00002145 # 7: lea rax, [rip - 0x102]
0x00002146 # 6: lea eax, [rip - 0x102]
0x00002150 # 7: lea rax, [rip - 0xd7]
0x00002151 # 6: lea eax, [rip - 0xd7]
0x0000215b # 7: lea rax, [rip - 0xac]
0x0000215c # 6: lea eax, [rip - 0xac]
0x00002166 # 7: lea rax, [rip - 0x7d]
0x00002167 # 6: lea eax, [rip - 0x7d]
0x00002171 # 7: lea rax, [rip - 0x4e]
0x00002172 # 6: lea eax, [rip - 0x4e]
0x000021a7 # 1: leave
0x000021a9 # 7: lea rax, [rbx + loc.encl_stack]
0x000021aa # 6: lea eax, [rbx + loc.encl_stack]
[0x00002000]> s 0x21a9
[0x000021a9]> pi 1
lea rax, [rbx + loc.encl_stack]
[0x000021a9]>
jarkko@suppilovahvero ~/Downloads (main)> rizin test_encl.elf
-- Use V! to enter into the visual panels mode (dwm style)
[0x00002000]> aaa
[x] Analyze all flags starting with sym. and entry0 (aa)
[x] Analyze function calls (aac)
[x] Analyze len bytes of instructions for references (aar)
[x] Check for classes
[x] Type matching analysis for all functions (aaft)
[x] Propagate noreturn information
[x] Use -AA or aaaa to perform additional experimental analysis.
[0x00002000]> /ad lea
0x0000206e # 7: lea rax, [rip + 0xf8b]
0x0000206f # 6: lea eax, [rip + 0xf8b]
0x0000207e # 1: leave
0x000020a1 # 7: lea rcx, [rip + 0xf58]
0x000020a2 # 6: lea ecx, [rip + 0xf58]
0x000020b4 # 1: leave
0x000020ee # 1: leave
0x00002128 # 1: leave
0x00002145 # 7: lea rax, [rip - 0x102]
0x00002146 # 6: lea eax, [rip - 0x102]
0x00002150 # 7: lea rax, [rip - 0xd7]
0x00002151 # 6: lea eax, [rip - 0xd7]
0x0000215b # 7: lea rax, [rip - 0xac]
0x0000215c # 6: lea eax, [rip - 0xac]
0x00002166 # 7: lea rax, [rip - 0x7d]
0x00002167 # 6: lea eax, [rip - 0x7d]
0x00002171 # 7: lea rax, [rip - 0x4e]
0x00002172 # 6: lea eax, [rip - 0x4e]
0x000021a7 # 1: leave
0x000021a9 # 7: lea rax, [rip + 0x5e50]
0x000021aa # 6: lea eax, [rip + 0x5e50]
[0x00002000]> s 0x21a9
[0x000021a9]> pi 1
lea rax, loc.encl_stack
[0x000021a9]>
BR, Jarkko
next prev parent reply other threads:[~2022-03-30 19:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 7:43 [PATCH v2 1/2] selftests/sgx: Use rip relative addressing for encl_stack Jarkko Sakkinen
2022-03-22 7:43 ` [PATCH v2 2/2] selftests/sgx: Make TCS table relocatable Jarkko Sakkinen
2022-03-28 21:49 ` [PATCH v2 1/2] selftests/sgx: Use rip relative addressing for encl_stack Reinette Chatre
2022-03-30 14:54 ` Jarkko Sakkinen
2022-03-30 14:56 ` Jarkko Sakkinen
2022-03-30 17:40 ` Reinette Chatre
[not found] ` <f68d472877b7136c32d8770603a3de38de59c322.camel@kernel.org>
2022-03-30 19:22 ` Jarkko Sakkinen [this message]
2022-03-30 20:05 ` Reinette Chatre
2022-03-30 20:40 ` Jarkko Sakkinen
2022-03-30 21:29 ` Reinette Chatre
2022-03-30 22:30 ` Jarkko Sakkinen
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