[PATCH] gdbstub: Fix segment fault for i386 and m68k

[PATCH] gdbstub: Fix segment fault for i386 and m68k

[Changbin Du]

With GByteArray, we should pass the object itself but not to plus an offset.

gdb log:
Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
__memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:384
384	../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S: No such file or directory.

Fixes: a010bdbe71 ("gdbstub: extend GByteArray to read register helpers")
Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
 target/i386/gdbstub.c | 2 +-
 target/m68k/helper.c  | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/target/i386/gdbstub.c b/target/i386/gdbstub.c
index f3d23b614e..b98a99500a 100644
--- a/target/i386/gdbstub.c
+++ b/target/i386/gdbstub.c
@@ -106,7 +106,7 @@ int x86_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
     } else if (n >= IDX_FP_REGS && n < IDX_FP_REGS + 8) {
         floatx80 *fp = (floatx80 *) &env->fpregs[n - IDX_FP_REGS];
         int len = gdb_get_reg64(mem_buf, cpu_to_le64(fp->low));
-        len += gdb_get_reg16(mem_buf + len, cpu_to_le16(fp->high));
+        len += gdb_get_reg16(mem_buf, cpu_to_le16(fp->high));
         return len;
     } else if (n >= IDX_XMM_REGS && n < IDX_XMM_REGS + CPU_NB_REGS) {
         n -= IDX_XMM_REGS;
diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index 014657c637..cad4083895 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -109,8 +109,8 @@ static int m68k_fpu_gdb_get_reg(CPUM68KState *env, GByteArray *mem_buf, int n)
 {
     if (n < 8) {
         int len = gdb_get_reg16(mem_buf, env->fregs[n].l.upper);
-        len += gdb_get_reg16(mem_buf + len, 0);
-        len += gdb_get_reg64(mem_buf + len, env->fregs[n].l.lower);
+        len += gdb_get_reg16(mem_buf, 0);
+        len += gdb_get_reg64(mem_buf, env->fregs[n].l.lower);
         return len;
     }
     switch (n) {
-- 
2.25.1

Re: [PATCH] gdbstub: Fix segment fault for i386 and m68k

[Laurent Vivier]

CC: Alex Bennée

The one for m68k is already queued by Alex.

Thanks,
Laurent

Le 12/04/2020 à 12:44, Changbin Du a écrit :
> With GByteArray, we should pass the object itself but not to plus an offset.
> 
> gdb log:
> Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
> __memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:384
> 384	../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S: No such file or directory.
> 
> Fixes: a010bdbe71 ("gdbstub: extend GByteArray to read register helpers")
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
>  target/i386/gdbstub.c | 2 +-
>  target/m68k/helper.c  | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/target/i386/gdbstub.c b/target/i386/gdbstub.c
> index f3d23b614e..b98a99500a 100644
> --- a/target/i386/gdbstub.c
> +++ b/target/i386/gdbstub.c
> @@ -106,7 +106,7 @@ int x86_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
>      } else if (n >= IDX_FP_REGS && n < IDX_FP_REGS + 8) {
>          floatx80 *fp = (floatx80 *) &env->fpregs[n - IDX_FP_REGS];
>          int len = gdb_get_reg64(mem_buf, cpu_to_le64(fp->low));
> -        len += gdb_get_reg16(mem_buf + len, cpu_to_le16(fp->high));
> +        len += gdb_get_reg16(mem_buf, cpu_to_le16(fp->high));
>          return len;
>      } else if (n >= IDX_XMM_REGS && n < IDX_XMM_REGS + CPU_NB_REGS) {
>          n -= IDX_XMM_REGS;
> diff --git a/target/m68k/helper.c b/target/m68k/helper.c
> index 014657c637..cad4083895 100644
> --- a/target/m68k/helper.c
> +++ b/target/m68k/helper.c
> @@ -109,8 +109,8 @@ static int m68k_fpu_gdb_get_reg(CPUM68KState *env, GByteArray *mem_buf, int n)
>  {
>      if (n < 8) {
>          int len = gdb_get_reg16(mem_buf, env->fregs[n].l.upper);
> -        len += gdb_get_reg16(mem_buf + len, 0);
> -        len += gdb_get_reg64(mem_buf + len, env->fregs[n].l.lower);
> +        len += gdb_get_reg16(mem_buf, 0);
> +        len += gdb_get_reg64(mem_buf, env->fregs[n].l.lower);
>          return len;
>      }
>      switch (n) {
> 

Re: [PATCH] gdbstub: Fix segment fault for i386 and m68k

[Changbin Du]

On Sun, Apr 12, 2020 at 02:58:56PM +0200, Laurent Vivier wrote:
> CC: Alex Bennée
> 
> The one for m68k is already queued by Alex.
>
Great. I will send x86 fix only. Thanks!

> Thanks,
> Laurent
> 
-- 
Cheers,
Changbin Du