[PATCH v4 08/23] x86/kgdb: Avoid redundant comparison of patched code

[Rick Edgecombe]

From: Nadav Amit <na...@vmware.com>

text_poke() already ensures that the written value is the correct one
and fails if that is not the case. There is no need for an additional
comparison. Remove it.

Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Nadav Amit <na...@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgeco...@intel.com>
---
 arch/x86/kernel/kgdb.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 2b203ee5b879..13b13311b792 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -747,7 +747,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long 
ip)
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
        int err;
-       char opc[BREAK_INSTR_SIZE];
 
        bpt->type = BP_BREAKPOINT;
        err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
@@ -766,11 +765,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
                return -EBUSY;
        text_poke_kgdb((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
                       BREAK_INSTR_SIZE);
-       err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
-       if (err)
-               return err;
-       if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
-               return -EINVAL;
        bpt->type = BP_POKE_BREAKPOINT;
 
        return err;
@@ -778,9 +772,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 
 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 {
-       int err;
-       char opc[BREAK_INSTR_SIZE];
-
        if (bpt->type != BP_POKE_BREAKPOINT)
                goto knl_write;
        /*
@@ -791,10 +782,7 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
                goto knl_write;
        text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr,
                       BREAK_INSTR_SIZE);
-       err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
-       if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
-               goto knl_write;
-       return err;
+       return 0;
 
 knl_write:
        return probe_kernel_write((char *)bpt->bpt_addr,
-- 
2.17.1