diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2018-05-22 09:00:00 +1000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-05-21 20:45:31 -0700 |
| commit | a048a07d7f4535baa4cbad6bc024f175317ab938 (patch) | |
| tree | 3ae572e2057a26a151957ccada417251121f41aa /arch/powerpc/include/asm/feature-fixups.h | |
| parent | c85061e6e0ee07e131b929e6a17bb2e20d19b321 (diff) | |
powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit
On some CPUs we can prevent a vulnerability related to store-to-load
forwarding by preventing store forwarding between privilege domains,
by inserting a barrier in kernel entry and exit paths.
This is known to be the case on at least Power7, Power8 and Power9
powerpc CPUs.
Barriers must be inserted generally before the first load after moving
to a higher privilege, and after the last store before moving to a
lower privilege, HV and PR privilege transitions must be protected.
Barriers are added as patch sections, with all kernel/hypervisor entry
points patched, and the exit points to lower privilge levels patched
similarly to the RFI flush patching.
Firmware advertisement is not implemented yet, so CPU flush types
are hard coded.
Thanks to Michal Suchánek for bug fixes and review.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/powerpc/include/asm/feature-fixups.h')
| -rw-r--r-- | arch/powerpc/include/asm/feature-fixups.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h index 1e82eb3caabd..a9b64df34e2a 100644 --- a/arch/powerpc/include/asm/feature-fixups.h +++ b/arch/powerpc/include/asm/feature-fixups.h @@ -187,6 +187,22 @@ label##3: \ FTR_ENTRY_OFFSET label##1b-label##3b; \ .popsection; +#define STF_ENTRY_BARRIER_FIXUP_SECTION \ +953: \ + .pushsection __stf_entry_barrier_fixup,"a"; \ + .align 2; \ +954: \ + FTR_ENTRY_OFFSET 953b-954b; \ + .popsection; + +#define STF_EXIT_BARRIER_FIXUP_SECTION \ +955: \ + .pushsection __stf_exit_barrier_fixup,"a"; \ + .align 2; \ +956: \ + FTR_ENTRY_OFFSET 955b-956b; \ + .popsection; + #define RFI_FLUSH_FIXUP_SECTION \ 951: \ .pushsection __rfi_flush_fixup,"a"; \ @@ -199,6 +215,9 @@ label##3: \ #ifndef __ASSEMBLY__ #include <linux/types.h> +extern long stf_barrier_fallback; +extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup; +extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup; extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup; void apply_feature_fixups(void); |