x86: set bp field in pt_regs properly

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kernel / entry_64.S

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cf3a0b2d00599adb2a79fefa991c0d8223059fba..25bb3f9b25527bc55ea01496a53e9bf727e6a289 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -667,6 +667,13 @@ END(stub_rt_sigreturn)
        SAVE_ARGS
        leaq -ARGOFFSET(%rsp),%rdi      # arg1 for handler
        pushq %rbp
+       /*
+        * Save rbp twice: One is for marking the stack frame, as usual, and the
+        * other, to fill pt_regs properly. This is because bx comes right
+        * before the last saved register in that structure, and not bp. If the
+        * base pointer were in the place bx is today, this would not be needed.
+        */
+       movq %rbp, -8(%rsp)
        CFI_ADJUST_CFA_OFFSET   8
        CFI_REL_OFFSET          rbp, 0
        movq %rsp,%rbp