Commit ee63291a authored by Xin Li's avatar Xin Li Committed by Borislav Petkov (AMD)
Browse files

x86/ptrace: Cleanup the definition of the pt_regs structure 



struct pt_regs is hard to read because the member or section related
comments are not aligned with the members.

The 'cs' and 'ss' members of pt_regs are type of 'unsigned long' while
in reality they are only 16-bit wide. This works so far as the
remaining space is unused, but FRED will use the remaining bits for
other purposes.

To prepare for FRED:

  - Cleanup the formatting
  - Convert 'cs' and 'ss' to u16 and embed them into an union
    with a u64
  - Fixup the related printk() format strings

Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Originally-by: default avatarH. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: default avatarXin Li <xin3.li@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarShan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-14-xin3.li@intel.com
parent cd6df3f3

arch/x86/entry/vsyscall/vsyscall_64.c

+1 −1
Original line number Diff line number Diff line
@@ -76,7 +76,7 @@ static void warn_bad_vsyscall(const char *level, struct pt_regs *regs, 
	if (!show_unhandled_signals)

		return;



	printk_ratelimited("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n",

	printk_ratelimited("%s%s[%d] %s ip:%lx cs:%x sp:%lx ax:%lx si:%lx di:%lx\n",

			   level, current->comm, task_pid_nr(current),

			   message, regs->ip, regs->cs,

			   regs->sp, regs->ax, regs->si, regs->di);

arch/x86/include/asm/ptrace.h

+35 −13
Original line number Diff line number Diff line
@@ -58,8 +58,9 @@ struct pt_regs { 


struct pt_regs {

	/*

 * C ABI says these regs are callee-preserved. They aren't saved on kernel entry

 * unless syscall needs a complete, fully filled "struct pt_regs".

	 * C ABI says these regs are callee-preserved. They aren't saved on

	 * kernel entry unless syscall needs a complete, fully filled

	 * "struct pt_regs".

	 */

	unsigned long r15;

	unsigned long r14;
@@ -67,6 +68,7 @@ struct pt_regs { 
	unsigned long r12;

	unsigned long bp;

	unsigned long bx;



	/* These regs are callee-clobbered. Always saved on kernel entry. */

	unsigned long r11;

	unsigned long r10;
@@ -77,18 +79,38 @@ struct pt_regs { 
	unsigned long dx;

	unsigned long si;

	unsigned long di;



	/*

 * On syscall entry, this is syscall#. On CPU exception, this is error code.

 * On hw interrupt, it's IRQ number:

	 * orig_ax is used on entry for:

	 * - the syscall number (syscall, sysenter, int80)

	 * - error_code stored by the CPU on traps and exceptions

	 * - the interrupt number for device interrupts

	 */

	unsigned long orig_ax;

/* Return frame for iretq */



	/* The IRETQ return frame starts here */

	unsigned long ip;

	unsigned long cs;



	union {

		/* The full 64-bit data slot containing CS */

		u64		csx;

		/* CS selector */

		u16		cs;

	};



	unsigned long flags;

	unsigned long sp;

	unsigned long ss;

/* top of stack page */



	union {

		/* The full 64-bit data slot containing SS */

		u64		ssx;

		/* SS selector */

		u16		ss;

	};



	/*

	 * Top of stack on IDT systems.

	 */

};



#endif /* !__i386__ */

arch/x86/kernel/process_64.c

+1 −1
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, 


	printk("%sFS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",

	       log_lvl, fs, fsindex, gs, gsindex, shadowgs);

	printk("%sCS:  %04lx DS: %04x ES: %04x CR0: %016lx\n",

	printk("%sCS:  %04x DS: %04x ES: %04x CR0: %016lx\n",

		log_lvl, regs->cs, ds, es, cr0);

	printk("%sCR2: %016lx CR3: %016lx CR4: %016lx\n",

		log_lvl, cr2, cr3, cr4);