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x86/retbleed: Add SKL call thunk

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Add the actual SKL call thunk for call depth accounting.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.101125588@infradead.org
This commit is contained in:
Thomas Gleixner 2022-09-15 13:11:29 +02:00 committed by Peter Zijlstra
parent 3b6c1747da
commit bbaceb189a
1 changed files with 20 additions and 5 deletions
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25
arch/x86/kernel/callthunks.c
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@ -7,6 +7,7 @@
#include <linux/moduleloader.h>
#include <asm/alternative.h>
#include <asm/asm-offsets.h>
#include <asm/cpu.h>
#include <asm/ftrace.h>
#include <asm/insn.h>
@ -55,7 +56,21 @@ static const struct core_text builtin_coretext = {
.name = "builtin",
};
static struct thunk_desc callthunk_desc __ro_after_init;
asm (
".pushsection .rodata \n"
".global skl_call_thunk_template \n"
"skl_call_thunk_template: \n"
__stringify(INCREMENT_CALL_DEPTH)" \n"
".global skl_call_thunk_tail \n"
"skl_call_thunk_tail: \n"
".popsection \n"
);
extern u8 skl_call_thunk_template[];
extern u8 skl_call_thunk_tail[];
#define SKL_TMPL_SIZE \
((unsigned int)(skl_call_thunk_tail - skl_call_thunk_template))
extern void error_entry(void);
extern void xen_error_entry(void);
@ -157,11 +172,11 @@ static const u8 nops[] = {
static __init_or_module void *patch_dest(void *dest, bool direct)
{
unsigned int tsize = callthunk_desc.template_size;
unsigned int tsize = SKL_TMPL_SIZE;
u8 *pad = dest - tsize;
/* Already patched? */
if (!bcmp(pad, callthunk_desc.template, tsize))
if (!bcmp(pad, skl_call_thunk_template, tsize))
return pad;
/* Ensure there are nops */
@ -171,9 +186,9 @@ static __init_or_module void *patch_dest(void *dest, bool direct)
}
if (direct)
memcpy(pad, callthunk_desc.template, tsize);
memcpy(pad, skl_call_thunk_template, tsize);
else
text_poke_copy_locked(pad, callthunk_desc.template, tsize, true);
text_poke_copy_locked(pad, skl_call_thunk_template, tsize, true);
return pad;
}