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authorDiana Craciun <diana.craciun@nxp.com>2019-04-11 21:46:18 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-17 08:36:42 +0200
commitd91460f2d0efc0fe6a197fc739e30edab6070456 (patch)
treef8b159803a00736195ee0541c23a523df01188b4
parentae361096d6857727275631d1d64bcd8fec2d8f25 (diff)
powerpc/fsl: Add infrastructure to fixup branch predictor flush
commit 76a5eaa38b15dda92cd6964248c39b5a6f3a4e9d upstream. In order to protect against speculation attacks (Spectre variant 2) on NXP PowerPC platforms, the branch predictor should be flushed when the privillege level is changed. This patch is adding the infrastructure to fixup at runtime the code sections that are performing the branch predictor flush depending on a boot arg parameter which is added later in a separate patch. Signed-off-by: Diana Craciun <diana.craciun@nxp.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--arch/powerpc/include/asm/feature-fixups.h12
-rw-r--r--arch/powerpc/include/asm/setup.h2
-rw-r--r--arch/powerpc/kernel/vmlinux.lds.S8
-rw-r--r--arch/powerpc/lib/feature-fixups.c23
4 files changed, 45 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index afd3efd38938..175128e19025 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/arch/powerpc/include/asm/feature-fixups.h
@@ -221,6 +221,17 @@ void setup_feature_keys(void);
FTR_ENTRY_OFFSET 953b-954b; \
.popsection;
+#define START_BTB_FLUSH_SECTION \
+955: \
+
+#define END_BTB_FLUSH_SECTION \
+956: \
+ .pushsection __btb_flush_fixup,"a"; \
+ .align 2; \
+957: \
+ FTR_ENTRY_OFFSET 955b-957b; \
+ FTR_ENTRY_OFFSET 956b-957b; \
+ .popsection;
#ifndef __ASSEMBLY__
@@ -229,6 +240,7 @@ 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;
extern long __start___barrier_nospec_fixup, __stop___barrier_nospec_fixup;
+extern long __start__btb_flush_fixup, __stop__btb_flush_fixup;
#endif
diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index d3e9da62d029..23ee67e279ae 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -65,6 +65,8 @@ void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
#endif
+void do_btb_flush_fixups(void);
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_POWERPC_SETUP_H */
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 5c6cf58943b9..50d365060855 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -164,6 +164,14 @@ SECTIONS
}
#endif /* CONFIG_PPC_BARRIER_NOSPEC */
+#ifdef CONFIG_PPC_FSL_BOOK3E
+ . = ALIGN(8);
+ __spec_btb_flush_fixup : AT(ADDR(__spec_btb_flush_fixup) - LOAD_OFFSET) {
+ __start__btb_flush_fixup = .;
+ *(__btb_flush_fixup)
+ __stop__btb_flush_fixup = .;
+ }
+#endif
EXCEPTION_TABLE(0)
NOTES :kernel :notes
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index b3e362437ec4..e6ed0ec94bc8 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -347,6 +347,29 @@ void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_
printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
}
+
+static void patch_btb_flush_section(long *curr)
+{
+ unsigned int *start, *end;
+
+ start = (void *)curr + *curr;
+ end = (void *)curr + *(curr + 1);
+ for (; start < end; start++) {
+ pr_devel("patching dest %lx\n", (unsigned long)start);
+ patch_instruction(start, PPC_INST_NOP);
+ }
+}
+
+void do_btb_flush_fixups(void)
+{
+ long *start, *end;
+
+ start = PTRRELOC(&__start__btb_flush_fixup);
+ end = PTRRELOC(&__stop__btb_flush_fixup);
+
+ for (; start < end; start += 2)
+ patch_btb_flush_section(start);
+}
#endif /* CONFIG_PPC_FSL_BOOK3E */
void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)