Merge tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Thomas Gleixner:

 - Improve retpoline code patching by separating it from alternatives
   which reduces memory footprint and allows to do better optimizations
   in the actual runtime patching.

 - Add proper retpoline support for x86/BPF

 - Address noinstr warnings in x86/kvm, lockdep and paravirtualization
   code

 - Add support to handle pv_opsindirect calls in the noinstr analysis

 - Classify symbols upfront and cache the result to avoid redundant
   str*cmp() invocations.

 - Add a CFI hash to reduce memory consumption which also reduces
   runtime on a allyesconfig by ~50%

 - Adjust XEN code to make objtool handling more robust and as a side
   effect to prevent text fragmentation due to placement of the
   hypercall page.

* tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  bpf,x86: Respect X86_FEATURE_RETPOLINE*
  bpf,x86: Simplify computing label offsets
  x86,bugs: Unconditionally allow spectre_v2=retpoline,amd
  x86/alternative: Add debug prints to apply_retpolines()
  x86/alternative: Try inline spectre_v2=retpoline,amd
  x86/alternative: Handle Jcc __x86_indirect_thunk_\reg
  x86/alternative: Implement .retpoline_sites support
  x86/retpoline: Create a retpoline thunk array
  x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h
  x86/asm: Fixup odd GEN-for-each-reg.h usage
  x86/asm: Fix register order
  x86/retpoline: Remove unused replacement symbols
  objtool,x86: Replace alternatives with .retpoline_sites
  objtool: Shrink struct instruction
  objtool: Explicitly avoid self modifying code in .altinstr_replacement
  objtool: Classify symbols
  objtool: Support pv_opsindirect calls for noinstr
  x86/xen: Rework the xen_{cpu,irq,mmu}_opsarrays
  x86/xen: Mark xen_force_evtchn_callback() noinstr
  x86/xen: Make irq_disable() noinstr
  ...

1 files changed, 19 insertions, 3 deletions

diff --git a/arch/x86/net/bpf_jit_comp32.c b/arch/x86/net/bpf_jit_comp32.c
index 3bfda5f502cb..da9b7cfa4632 100644
--- a/arch/x86/net/bpf_jit_comp32.c
+++ b/arch/x86/net/bpf_jit_comp32.c
@@ -15,6 +15,7 @@
 #include <asm/cacheflush.h>
 #include <asm/set_memory.h>
 #include <asm/nospec-branch.h>
+#include <asm/asm-prototypes.h>
 #include <linux/bpf.h>
 
 /*
@@ -1267,6 +1268,21 @@ static void emit_epilogue(u8 **pprog, u32 stack_depth)
 	*pprog = prog;
 }
 
+static int emit_jmp_edx(u8 **pprog, u8 *ip)
+{
+	u8 *prog = *pprog;
+	int cnt = 0;
+
+#ifdef CONFIG_RETPOLINE
+	EMIT1_off32(0xE9, (u8 *)__x86_indirect_thunk_edx - (ip + 5));
+#else
+	EMIT2(0xFF, 0xE2);
+#endif
+	*pprog = prog;
+
+	return cnt;
+}
+
 /*
  * Generate the following code:
  * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
@@ -1280,7 +1296,7 @@ static void emit_epilogue(u8 **pprog, u32 stack_depth)
  *   goto *(prog->bpf_func + prologue_size);
  * out:
  */
-static void emit_bpf_tail_call(u8 **pprog)
+static void emit_bpf_tail_call(u8 **pprog, u8 *ip)
 {
 	u8 *prog = *pprog;
 	int cnt = 0;
@@ -1362,7 +1378,7 @@ static void emit_bpf_tail_call(u8 **pprog)
 	 * eax == ctx (1st arg)
 	 * edx == prog->bpf_func + prologue_size
 	 */
-	RETPOLINE_EDX_BPF_JIT();
+	cnt += emit_jmp_edx(&prog, ip + cnt);
 
 	if (jmp_label1 == -1)
 		jmp_label1 = cnt;
@@ -2122,7 +2138,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
 			break;
 		}
 		case BPF_JMP | BPF_TAIL_CALL:
-			emit_bpf_tail_call(&prog);
+			emit_bpf_tail_call(&prog, image + addrs[i - 1]);
 			break;
 
 		/* cond jump */