[PATCH stable v4.9 05/35] powerpc/64s: Patch barrier_nospec in modules

Michael Ellerman
2019-04-11T11:46:44Z

From: Michal Suchanek <msuchanek@suse.de>

commit 815069ca57c142eb71d27439bc27f41a433a67b3 upstream.

Note that unlike RFI which is patched only in kernel the nospec state
reflects settings at the time the module was loaded.

Iterating all modules and re-patching every time the settings change
is not implemented.

Based on lwsync patching.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/include/asm/setup.h | 7 +++++++
arch/powerpc/kernel/module.c | 6 ++++++
arch/powerpc/kernel/security.c | 2 +-
arch/powerpc/lib/feature-fixups.c | 16 +++++++++++++---
4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 709f4e739ae8..a225b5c42e76 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -52,6 +52,13 @@ enum l1d_flush_type {
void setup_rfi_flush(enum l1d_flush_type, bool enable);
void do_rfi_flush_fixups(enum l1d_flush_type types);
void do_barrier_nospec_fixups(bool enable);
+extern bool barrier_nospec_enabled;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
+#else
+static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
+#endif

#endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 30b89d5cbb03..d30f0626dcd0 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -72,6 +72,12 @@ int module_finalize(const Elf_Ehdr *hdr,
do_feature_fixups(powerpc_firmware_features,
(void *)sect->sh_addr,
(void *)sect->sh_addr + sect->sh_size);
+
+ sect = find_section(hdr, sechdrs, "__spec_barrier_fixup");
+ if (sect != NULL)
+ do_barrier_nospec_fixups_range(barrier_nospec_enabled,
+ (void *)sect->sh_addr,
+ (void *)sect->sh_addr + sect->sh_size);
#endif

sect = find_section(hdr, sechdrs, "__lwsync_fixup");
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 8b1cf9c81b82..34d436fe2498 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -15,7 +15,7 @@

unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;

-static bool barrier_nospec_enabled;
+bool barrier_nospec_enabled;

static void enable_barrier_nospec(bool enable)
{
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index f82ae6bb2365..a1222c441df5 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -278,14 +278,14 @@ void do_rfi_flush_fixups(enum l1d_flush_type types)
: "unknown");
}

-void do_barrier_nospec_fixups(bool enable)
+void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_end)
{
unsigned int instr, *dest;
long *start, *end;
int i;

- start = PTRRELOC(&__start___barrier_nospec_fixup),
- end = PTRRELOC(&__stop___barrier_nospec_fixup);
+ start = fixup_start;
+ end = fixup_end;

instr = 0x60000000; /* nop */

@@ -304,6 +304,16 @@ void do_barrier_nospec_fixups(bool enable)
printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
}

+void do_barrier_nospec_fixups(bool enable)
+{
+ void *start, *end;
+
+ start = PTRRELOC(&__start___barrier_nospec_fixup),
+ end = PTRRELOC(&__stop___barrier_nospec_fixup);
+
+ do_barrier_nospec_fixups_range(enable, start, end);
+}
+
#endif /* CONFIG_PPC_BOOK3S_64 */

void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
--
2.20.1