[PATCH 4.9 068/171] s390/disassembler: dont hide instruction addresses

Greg Kroah-Hartman
2020-01-02T22:31:08Z

From: Ilya Leoshkevich <iii@linux.ibm.com>

[ Upstream commit 544f1d62e3e6c6e6d17a5e56f6139208acb5ff46 ]

Due to kptr_restrict, JITted BPF code is now displayed like this:

000000000b6ed1b2: ebdff0800024 stmg %r13,%r15,128(%r15)
000000004cde2ba0: 41d0f040 la %r13,64(%r15)
00000000fbad41b0: a7fbffa0 aghi %r15,-96

Leaking kernel addresses to dmesg is not a concern in this case, because
this happens only when JIT debugging is explicitly activated, which only
root can do.

Use %px in this particular instance, and also to print an instruction
address in show_code and PCREL (e.g. brasl) arguments in print_insn.
While at present functionally equivalent to %016lx, %px is recommended
by Documentation/core-api/printk-formats.rst for such cases.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/dis.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
index aaf9dab3c193..f9dca1aed9a4 100644
--- a/arch/s390/kernel/dis.c
+++ b/arch/s390/kernel/dis.c
@@ -1930,10 +1930,11 @@ static int print_insn(char *buffer, unsigned char *code, unsigned long addr)
ptr += sprintf(ptr, "%%c%i", value);
else if (operand->flags & OPERAND_VR)
ptr += sprintf(ptr, "%%v%i", value);
- else if (operand->flags & OPERAND_PCREL)
- ptr += sprintf(ptr, "%lx", (signed int) value
- + addr);
- else if (operand->flags & OPERAND_SIGNED)
+ else if (operand->flags & OPERAND_PCREL) {
+ void *pcrel = (void *)((int)value + addr);
+
+ ptr += sprintf(ptr, "%px", pcrel);
+ } else if (operand->flags & OPERAND_SIGNED)
ptr += sprintf(ptr, "%i", value);
else
ptr += sprintf(ptr, "%u", value);
@@ -2005,7 +2006,7 @@ void show_code(struct pt_regs *regs)
else
*ptr++ = ' ';
addr = regs->psw.addr + start - 32;
- ptr += sprintf(ptr, "%016lx: ", addr);
+ ptr += sprintf(ptr, "%px: ", (void *)addr);
if (start + opsize >= end)
break;
for (i = 0; i < opsize; i++)
@@ -2033,7 +2034,7 @@ void print_fn_code(unsigned char *code, unsigned long len)
opsize = insn_length(*code);
if (opsize > len)
break;
- ptr += sprintf(ptr, "%p: ", code);
+ ptr += sprintf(ptr, "%px: ", code);
for (i = 0; i < opsize; i++)
ptr += sprintf(ptr, "%02x", code[i]);
*ptr++ = '\t';
--
2.20.1