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powerpc: add exit_flags field in pt_regs

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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
This commit is contained in:
Mukesh Kumar Chaurasiya
2026-04-27 17:57:39 +05:30
committed by Madhavan Srinivasan
parent 02565a782c
commit d7a6797e0b
3 changed files with 13 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/powerpc/include/asm/ptrace.h
View File

@@ -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)

14
arch/powerpc/include/uapi/asm/ptrace.h
View File

@@ -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__ */

1
arch/powerpc/kernel/ptrace/ptrace.c
View File

@@ -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));