powerpc: add exit_flags field in pt_regs

Add a new field `exit_flags` in the pt_regs structure. This field will hold
the flags set during interrupt or syscall execution that are required during
exit to user mode.

Specifically, the `TIF_RESTOREALL` flag, stored in this field, helps the
exit routine determine if any NVGPRs were modified and need to be restored
before returning to userspace.

This addition ensures a clean and architecture-specific mechanism to track
per-syscall or per-interrupt state transitions related to register restore.

Changes:
 - Add `exit_flags` and `__pt_regs_pad` to maintain 16-byte stack alignment
 - Update asm-offsets.c and ptrace.c for offset and validation
 - Update PT_* constants in uapi header to reflect the new layout

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
Tested-by: Samir M <samir@linux.ibm.com>
Tested-by: David Gow <davidgow@google.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260427122742.210074-6-mkchauras@gmail.com

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 94aa1de2b06e19f257adff807f40e2a3026fa3de..2e741ea57b80765b4e06e341e468098d8d7b7098 100644 (file)
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -53,6 +53,9 @@ struct pt_regs
                                unsigned long esr;
                        };
                        unsigned long result;
+                       unsigned long exit_flags;
+                       /* Maintain 16 byte interrupt stack alignment */
+                       unsigned long __pt_regs_pad[3];
                };
        };
 #if defined(CONFIG_PPC64) || defined(CONFIG_PPC_KUAP)

diff --git a/arch/powerpc/include/uapi/asm/ptrace.h b/arch/powerpc/include/uapi/asm/ptrace.h
index 01e630149d48e131ca7f7f12ba920dc07bf994cb..a393b7f2760a2e1aaf230a3bf71d3ccfd0061362 100644 (file)
--- a/arch/powerpc/include/uapi/asm/ptrace.h
+++ b/arch/powerpc/include/uapi/asm/ptrace.h
@@ -55,6 +55,8 @@ struct pt_regs
        unsigned long dar;              /* Fault registers */
        unsigned long dsisr;            /* on 4xx/Book-E used for ESR */
        unsigned long result;           /* Result of a system call */
+       unsigned long exit_flags;       /* System call exit flags */
+       unsigned long __pt_regs_pad[3]; /* Maintain 16 byte interrupt stack alignment */
 };
 
 #endif /* __ASSEMBLER__ */
@@ -114,10 +116,12 @@ struct pt_regs
 #define PT_DAR 41
 #define PT_DSISR 42
 #define PT_RESULT 43
-#define PT_DSCR 44
-#define PT_REGS_COUNT 44
+#define PT_EXIT_FLAGS 44
+#define PT_PAD 47 /* 3 times */
+#define PT_DSCR 48
+#define PT_REGS_COUNT 48
 
-#define PT_FPR0        48      /* each FP reg occupies 2 slots in this space */
+#define PT_FPR0        (PT_REGS_COUNT + 4)     /* each FP reg occupies 2 slots in this space */
 
 #ifndef __powerpc64__
 
@@ -129,7 +133,7 @@ struct pt_regs
 #define PT_FPSCR (PT_FPR0 + 32)        /* each FP reg occupies 1 slot in 64-bit space */
 
 
-#define PT_VR0 82      /* each Vector reg occupies 2 slots in 64-bit */
+#define PT_VR0 (PT_FPSCR + 2)  /* <82> each Vector reg occupies 2 slots in 64-bit */
 #define PT_VSCR (PT_VR0 + 32*2 + 1)
 #define PT_VRSAVE (PT_VR0 + 33*2)
 
@@ -137,7 +141,7 @@ struct pt_regs
 /*
  * Only store first 32 VSRs here. The second 32 VSRs in VR0-31
  */
-#define PT_VSR0 150    /* each VSR reg occupies 2 slots in 64-bit */
+#define PT_VSR0        (PT_VRSAVE + 2) /* each VSR reg occupies 2 slots in 64-bit */
 #define PT_VSR31 (PT_VSR0 + 2*31)
 #endif /* __powerpc64__ */
 

diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index c6997df632873d20f76ffad06b279d8964cffa0d..2134b6d155ff669c2b07477c8b76feefb132cecb 100644 (file)
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c
@@ -432,6 +432,7 @@ void __init pt_regs_check(void)
        CHECK_REG(PT_DAR, dar);
        CHECK_REG(PT_DSISR, dsisr);
        CHECK_REG(PT_RESULT, result);
+       CHECK_REG(PT_EXIT_FLAGS, exit_flags);
        #undef CHECK_REG
 
        BUILD_BUG_ON(PT_REGS_COUNT != sizeof(struct user_pt_regs) / sizeof(unsigned long));