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| author | Peter Zijlstra <peterz@infradead.org> | 2022-05-06 14:14:34 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-05-06 15:57:02 +0200 |
| commit | 8c42819b61b8340cff0643e65b5ce6a4144ab155 (patch) | |
| tree | 004465a4e2c22446f5396768f49c5f197720c71f /arch/x86/entry/calling.h | |
| parent | d205222eb6a8e5e70c21200beb81c6e19ec211d6 (diff) | |
| download | linux-stable-8c42819b61b8340cff0643e65b5ce6a4144ab155.tar.gz linux-stable-8c42819b61b8340cff0643e65b5ce6a4144ab155.tar.bz2 linux-stable-8c42819b61b8340cff0643e65b5ce6a4144ab155.zip | |
x86/entry: Use PUSH_AND_CLEAR_REGS for compat
Since the upper regs don't exist for ia32 code, preserving them
doesn't hurt and it simplifies the code.
This doesn't add any attack surface that would not already be
available through INT80.
Notably:
- 32bit SYSENTER: didn't clear si, dx, cx.
- 32bit SYSCALL, INT80: *do* clear si since the C functions don't
take a second argument.
- 64bit: didn't clear si since the C functions take a second
argument; except the error_entry path might have only one argument,
so clearing si was missing here.
32b SYSENTER should be clearing all those 3 registers, nothing uses them
and selftests pass.
Unconditionally clear rsi since it simplifies code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.293889636@infradead.org
Diffstat (limited to 'arch/x86/entry/calling.h')
| -rw-r--r-- | arch/x86/entry/calling.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index a4c061fb7c6e..debbe94aa3db 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -99,6 +99,7 @@ For 32-bit we have the following conventions - kernel is built with * well before they could be put to use in a speculative execution * gadget. */ + xorl %esi, %esi /* nospec si */ xorl %edx, %edx /* nospec dx */ xorl %ecx, %ecx /* nospec cx */ xorl %r8d, %r8d /* nospec r8 */ |