Fixes for 5.4

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-5.4/arm64-alternatives-don-t-patch-up-internal-branches.patch b/queue-5.4/arm64-alternatives-don-t-patch-up-internal-branches.patch
new file mode 100644 (file)
index 0000000..386e10a
--- /dev/null
+++ b/queue-5.4/arm64-alternatives-don-t-patch-up-internal-branches.patch
@@ -0,0 +1,64 @@
+From fbe82156997416d75ee65f80ede3be5e0c0ff6b4 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Thu, 9 Jul 2020 15:59:53 +0300
+Subject: arm64/alternatives: don't patch up internal branches
+
+From: Ard Biesheuvel <ardb@kernel.org>
+
+[ Upstream commit 5679b28142193a62f6af93249c0477be9f0c669b ]
+
+Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement
+sequences") moved the alternatives replacement sequences into subsections,
+in order to keep the as close as possible to the code that they replace.
+
+Unfortunately, this broke the logic in branch_insn_requires_update,
+which assumed that any branch into kernel executable code was a branch
+that required updating, which is no longer the case now that the code
+sequences that are patched in are in the same section as the patch site
+itself.
+
+So the only way to discriminate branches that require updating and ones
+that don't is to check whether the branch targets the replacement sequence
+itself, and so we can drop the call to kernel_text_address() entirely.
+
+Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences")
+Reported-by: Alexandru Elisei <alexandru.elisei@arm.com>
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
+Link: https://lore.kernel.org/r/20200709125953.30918-1-ardb@kernel.org
+Signed-off-by: Will Deacon <will@kernel.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/arm64/kernel/alternative.c | 16 ++--------------
+ 1 file changed, 2 insertions(+), 14 deletions(-)
+
+diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
+index d1757ef1b1e74..73039949b5ce2 100644
+--- a/arch/arm64/kernel/alternative.c
++++ b/arch/arm64/kernel/alternative.c
+@@ -43,20 +43,8 @@ bool alternative_is_applied(u16 cpufeature)
+  */
+ static bool branch_insn_requires_update(struct alt_instr *alt, unsigned long pc)
+ {
+-      unsigned long replptr;
+-
+-      if (kernel_text_address(pc))
+-              return true;
+-
+-      replptr = (unsigned long)ALT_REPL_PTR(alt);
+-      if (pc >= replptr && pc <= (replptr + alt->alt_len))
+-              return false;
+-
+-      /*
+-       * Branching into *another* alternate sequence is doomed, and
+-       * we're not even trying to fix it up.
+-       */
+-      BUG();
++      unsigned long replptr = (unsigned long)ALT_REPL_PTR(alt);
++      return !(pc >= replptr && pc <= (replptr + alt->alt_len));
+ }
+ 
+ #define align_down(x, a)      ((unsigned long)(x) & ~(((unsigned long)(a)) - 1))
+-- 
+2.25.1
+

diff --git a/queue-5.4/series b/queue-5.4/series
index cd5a2be56510306150839a466e6daa98370b440c..7c74c59c136661940c5fedf805b6e3126de8496a 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -42,3 +42,4 @@ arm64-alternatives-use-subsections-for-replacement-s.patch
 tpm_tis-extra-chip-ops-check-on-error-path-in-tpm_ti.patch
 gfs2-read-only-mounts-should-grab-the-sd_freeze_gl-g.patch
 i2c-eg20t-load-module-automatically-if-id-matches.patch
+arm64-alternatives-don-t-patch-up-internal-branches.patch