[PATCH 7/9] x86/dumpstack: Add a show_ip() function

Borislav Petkov
2018-04-17T16:14:00Z

... which shows the Instruction Pointer along with the insn bytes around
it. Use it whenever we print rIP. Drop the rIP < PAGE_OFFSET check since
our probe_kernel_read() can handle any address properly.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/include/asm/stacktrace.h | 1 +
arch/x86/kernel/dumpstack.c | 23 +++++++++++++----------
arch/x86/kernel/process_32.c | 8 +++-----
3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 0630eeb18bbc..b6dc698f992a 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -112,4 +112,5 @@ static inline unsigned long caller_frame_pointer(void)
}

void show_opcodes(u8 *rip, const char *loglvl);
+void show_ip(struct pt_regs *regs, const char *loglvl);
#endif /* _ASM_X86_STACKTRACE_H */
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1592d0c3ebb5..82da808b5c36 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -94,9 +94,19 @@ void show_opcodes(u8 *rip, const char *loglvl)
pr_cont("\n");
}

+void show_ip(struct pt_regs *regs, const char *loglvl)
+{
+#ifdef CONFIG_X86_32
+ printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
+#else
+ printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
+#endif
+ show_opcodes((u8 *)regs->ip, loglvl);
+}
+
void show_iret_regs(struct pt_regs *regs)
{
- printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
+ show_ip(regs, KERN_DEFAULT);
printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
regs->sp, regs->flags);
}
@@ -392,15 +402,8 @@ void show_regs(struct pt_regs *regs)
__show_regs(regs, all);

/*
- * When in-kernel, we also print out the stack and code at the
- * time of the fault..
+ * When in-kernel, we also print out the stack at the time of the fault..
*/
- if (!user_mode(regs)) {
+ if (!user_mode(regs))
show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
-
- if (regs->ip < PAGE_OFFSET)
- printk(KERN_DEFAULT "Code: Bad RIP value.\n");
- else
- show_opcodes((u8 *)regs->ip, KERN_DEFAULT);
- }
}
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 5224c6099184..0ae659de21eb 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -76,16 +76,14 @@ void __show_regs(struct pt_regs *regs, int all)
savesegment(gs, gs);
}

- printk(KERN_DEFAULT "EIP: %pS\n", (void *)regs->ip);
- printk(KERN_DEFAULT "EFLAGS: %08lx CPU: %d\n", regs->flags,
- raw_smp_processor_id());
+ show_ip(regs, KERN_DEFAULT);

printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
regs->si, regs->di, regs->bp, sp);
- printk(KERN_DEFAULT " DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
- (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
+ printk(KERN_DEFAULT "DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n",
+ (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss, regs->flags);

if (!all)
return;
--
2.13.0