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ARM: Spectre-BHB workaround

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commit b9baf5c8c5c356757f4f9d8180b5e9d234065bc3 upstream.

Workaround the Spectre BHB issues for Cortex-A15, Cortex-A57,
Cortex-A72, Cortex-A73 and Cortex-A75. We also include Brahma B15 as
well to be safe, which is affected by Spectre V2 in the same ways as
Cortex-A15.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
[changes due to lack of SYSTEM_FREEING_INITMEM - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Russell King (Oracle)
2022-02-10 16:05:45 +00:00
committed by Greg Kroah-Hartman
parent 29d9b56df1
commit 3f9c958e35
9 changed files with 254 additions and 9 deletions
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38
arch/arm/kernel/traps.c
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@@ -30,6 +30,7 @@
#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/exception.h>
#include <asm/spectre.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/ptrace.h>
@@ -820,6 +821,43 @@ static void flush_vectors(void *vma, size_t offset, size_t size)
flush_icache_range(start, end);
}
#ifdef CONFIG_HARDEN_BRANCH_HISTORY
int spectre_bhb_update_vectors(unsigned int method)
{
extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
void *vec_start, *vec_end;
if (system_state > SYSTEM_SCHEDULING) {
pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
smp_processor_id());
return SPECTRE_VULNERABLE;
}
switch (method) {
case SPECTRE_V2_METHOD_LOOP8:
vec_start = __vectors_bhb_loop8_start;
vec_end = __vectors_bhb_loop8_end;
break;
case SPECTRE_V2_METHOD_BPIALL:
vec_start = __vectors_bhb_bpiall_start;
vec_end = __vectors_bhb_bpiall_end;
break;
default:
pr_err("CPU%u: unknown Spectre BHB state %d\n",
smp_processor_id(), method);
return SPECTRE_VULNERABLE;
}
copy_from_lma(vectors_page, vec_start, vec_end);
flush_vectors(vectors_page, 0, vec_end - vec_start);
return SPECTRE_MITIGATED;
}
#endif
void __init early_trap_init(void *vectors_base)
{
extern char __stubs_start[], __stubs_end[];