On January 31, 2024 1:14:52 PM PST, tip-bot2 for Xin Li <tip-bot2@xxxxxxxxxxxxx> wrote: >The following commit has been merged into the x86/fred branch of tip: > >Commit-ID: ee63291aa8287cb7ded767d340155fe8681fc075 >Gitweb: https://git.kernel.org/tip/ee63291aa8287cb7ded767d340155fe8681fc075 >Author: Xin Li <xin3.li@xxxxxxxxx> >AuthorDate: Tue, 05 Dec 2023 02:50:02 -08:00 >Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx> >CommitterDate: Wed, 31 Jan 2024 22:01:13 +01:00 > >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: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >Originally-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx> >Signed-off-by: Xin Li <xin3.li@xxxxxxxxx> >Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> >Tested-by: Shan Kang <shan.kang@xxxxxxxxx> >Link: https://lore.kernel.org/r/20231205105030.8698-14-xin3.li@xxxxxxxxx >--- > arch/x86/entry/vsyscall/vsyscall_64.c | 2 +- > arch/x86/include/asm/ptrace.h | 48 ++++++++++++++++++-------- > arch/x86/kernel/process_64.c | 2 +- > 3 files changed, 37 insertions(+), 15 deletions(-) > >diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c >index e0ca812..a3c0df1 100644 >--- a/arch/x86/entry/vsyscall/vsyscall_64.c >+++ b/arch/x86/entry/vsyscall/vsyscall_64.c >@@ -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); >diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h >index f4db78b..b268cd2 100644 >--- a/arch/x86/include/asm/ptrace.h >+++ b/arch/x86/include/asm/ptrace.h >@@ -57,17 +57,19 @@ struct pt_regs { > #else /* __i386__ */ > > 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; > unsigned long r13; > unsigned long r12; > unsigned long bp; > unsigned long bx; >-/* These regs are callee-clobbered. Always saved on kernel entry. */ >+ >+ /* These regs are callee-clobbered. Always saved on kernel entry. */ > unsigned long r11; > unsigned long r10; > unsigned long r9; >@@ -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__ */ >diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c >index 33b2687..0f78b58 100644 >--- a/arch/x86/kernel/process_64.c >+++ b/arch/x86/kernel/process_64.c >@@ -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); Incidentally, the comment about callee-saved registers is long since both obsolete and is now outright wrong. The next version of gcc (14 I think) will have an attribute to turn off saving registers which we can use for top-level C functions.
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