diff mbox series

[v2,3/5] gdbstub: Save target's siginfo

Message ID 20240307182623.1450717-3-gustavo.romero@linaro.org (mailing list archive)
State New, archived
Headers show
Series [v2,1/5] gdbstub: Rename back gdb_handlesig | expand

Commit Message

Gustavo Romero March 7, 2024, 6:26 p.m. UTC
Save target's siginfo into gdbserver_state so it can be used later, for
example, in any stub that requires the target's si_signo and si_code.

This change affects only linux-user mode.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
---
 gdbstub/internals.h    |  3 +++
 gdbstub/user-target.c  |  3 ++-
 gdbstub/user.c         | 14 ++++++++++----
 include/gdbstub/user.h |  6 +++++-
 linux-user/main.c      |  2 +-
 linux-user/signal.c    |  5 ++++-
 6 files changed, 25 insertions(+), 8 deletions(-)

Comments

Richard Henderson March 7, 2024, 9:09 p.m. UTC | #1
On 3/7/24 08:26, Gustavo Romero wrote:
> Save target's siginfo into gdbserver_state so it can be used later, for
> example, in any stub that requires the target's si_signo and si_code.
> 
> This change affects only linux-user mode.
> 
> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   gdbstub/internals.h    |  3 +++
>   gdbstub/user-target.c  |  3 ++-
>   gdbstub/user.c         | 14 ++++++++++----
>   include/gdbstub/user.h |  6 +++++-
>   linux-user/main.c      |  2 +-
>   linux-user/signal.c    |  5 ++++-
>   6 files changed, 25 insertions(+), 8 deletions(-)
> 
> diff --git a/gdbstub/internals.h b/gdbstub/internals.h
> index 56b7c13b75..a7cc69dab3 100644
> --- a/gdbstub/internals.h
> +++ b/gdbstub/internals.h
> @@ -58,6 +58,9 @@ typedef struct GDBState {
>       int line_csum; /* checksum at the end of the packet */
>       GByteArray *last_packet;
>       int signal;
> +#ifdef CONFIG_USER_ONLY
> +    uint8_t siginfo[MAX_SIGINFO_LENGTH];
> +#endif

If we this in GDBUserState in user.c -- no need for ifdefs then.

> --- a/gdbstub/user-target.c
> +++ b/gdbstub/user-target.c
> @@ -10,11 +10,12 @@
>   #include "qemu/osdep.h"
>   #include "exec/gdbstub.h"
>   #include "qemu.h"
> -#include "internals.h"
>   #ifdef CONFIG_LINUX
>   #include "linux-user/loader.h"
>   #include "linux-user/qemu.h"
> +#include "gdbstub/user.h"
>   #endif
> +#include "internals.h"
>   
>   /*
>    * Map target signal numbers to GDB protocol signal numbers and vice

Why are any changes required here?
Perhaps this is improper patch split from one of the others?

> @@ -140,6 +141,11 @@ int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
>           return sig;
>       }
>   
> +    if (siginfo) {
> +        /* Save target-specific siginfo. */
> +        memcpy(gdbserver_state.siginfo, siginfo, siginfo_len);
> +    }

A comment here about asserting the size at compile-time elsewhere would be welcome for 
future code browsers.

Need to record siginfo_len for later use -- you don't want to expose all 128 bytes if the 
actual structure is smaller.

> @@ -510,7 +516,7 @@ void gdb_breakpoint_remove_all(CPUState *cs)
>   void gdb_syscall_handling(const char *syscall_packet)
>   {
>       gdb_put_packet(syscall_packet);
> -    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL);
> +    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL, NULL, 0);
>   }
>   
>   static bool should_catch_syscall(int num)
> @@ -528,7 +534,7 @@ void gdb_syscall_entry(CPUState *cs, int num)
>   {
>       if (should_catch_syscall(num)) {
>           g_autofree char *reason = g_strdup_printf("syscall_entry:%x;", num);
> -        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
> +        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
>       }
>   }
>   
> @@ -536,7 +542,7 @@ void gdb_syscall_return(CPUState *cs, int num)
>   {
>       if (should_catch_syscall(num)) {
>           g_autofree char *reason = g_strdup_printf("syscall_return:%x;", num);
> -        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
> +        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
>       }

All of this makes me wonder if we should provide a different interface for syscalls, even 
if it uses the same code paths internally.

Do we want to zero the gdbserver siginfo to indicate that the contents are no longer 
valid?  I know it's not a real signal delivered to the process, but might we need to 
construct a simple siginfo struct to match the sigtrap?


r~
Alex Bennée March 7, 2024, 10:33 p.m. UTC | #2
Richard Henderson <richard.henderson@linaro.org> writes:

> On 3/7/24 08:26, Gustavo Romero wrote:
>> Save target's siginfo into gdbserver_state so it can be used later, for
>> example, in any stub that requires the target's si_signo and si_code.
>> This change affects only linux-user mode.
>> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   gdbstub/internals.h    |  3 +++
>>   gdbstub/user-target.c  |  3 ++-
>>   gdbstub/user.c         | 14 ++++++++++----
>>   include/gdbstub/user.h |  6 +++++-
>>   linux-user/main.c      |  2 +-
>>   linux-user/signal.c    |  5 ++++-
>>   6 files changed, 25 insertions(+), 8 deletions(-)
>> diff --git a/gdbstub/internals.h b/gdbstub/internals.h
>> index 56b7c13b75..a7cc69dab3 100644
>> --- a/gdbstub/internals.h
>> +++ b/gdbstub/internals.h
>> @@ -58,6 +58,9 @@ typedef struct GDBState {
>>       int line_csum; /* checksum at the end of the packet */
>>       GByteArray *last_packet;
>>       int signal;
>> +#ifdef CONFIG_USER_ONLY
>> +    uint8_t siginfo[MAX_SIGINFO_LENGTH];
>> +#endif
>
> If we this in GDBUserState in user.c -- no need for ifdefs then.

Although it does break on FreeBSD's user target:

  FAILED: libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o 
  cc -m64 -mcx16 -Ilibqemu-arm-bsd-user.fa.p -I. -I.. -Itarget/arm -I../target/arm -I../common-user/host/x86_64 -I../bsd-user/include -Ibsd-user/freebsd -I../bsd-user/freebsd -I../bsd-user/host/x86_64 -Ibsd-user -I../bsd-user -I../bsd-user/arm -Iqapi -Itrace -Iui -Iui/shader -I/usr/local/include/capstone -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -fstack-protector-strong -Wempty-body -Wendif-labels -Wexpansion-to-defined -Wformat-security -Wformat-y2k -Wignored-qualifiers -Winit-self -Wmissing-format-attribute -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wredundant-decls -Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings -Wno-gnu-variable-sized-type-not-at-end -Wno-initializer-overrides -Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value -Wno-string-plus-int -Wno-tautological-type-limit-compare -Wno-typedef-redefinition -Wthread-safety -iquote . -iquote /tmp/cirrus-ci-build -iquote /tmp/cirrus-ci-build/include -iquote /tmp/cirrus-ci-build/host/include/x86_64 -iquote /tmp/cirrus-ci-build/host/include/generic -iquote /tmp/cirrus-ci-build/tcg/i386 -pthread -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero -fPIE -DNEED_CPU_H '-DCONFIG_TARGET="arm-bsd-user-config-target.h"' '-DCONFIG_DEVICES="arm-bsd-user-config-devices.h"' -MD -MQ libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -MF libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o.d -o libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -c ../gdbstub/user-target.c
  In file included from ../gdbstub/user-target.c:18:
  ../gdbstub/internals.h:62:21: error: use of undeclared identifier 'MAX_SIGINFO_LENGTH'
     62 |     uint8_t siginfo[MAX_SIGINFO_LENGTH];
        |                     ^
  1 error generated.
  [2084/6731] Compiling C object libqemu-arm

See: https://gitlab.com/stsquad/qemu/-/jobs/6345829419

<snip>
Gustavo Romero March 8, 2024, 5:01 p.m. UTC | #3
Hi Alex,

On 3/7/24 7:33 PM, Alex Bennée wrote:
> Richard Henderson <richard.henderson@linaro.org> writes:
> 
>> On 3/7/24 08:26, Gustavo Romero wrote:
>>> Save target's siginfo into gdbserver_state so it can be used later, for
>>> example, in any stub that requires the target's si_signo and si_code.
>>> This change affects only linux-user mode.
>>> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
>>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
>>> ---
>>>    gdbstub/internals.h    |  3 +++
>>>    gdbstub/user-target.c  |  3 ++-
>>>    gdbstub/user.c         | 14 ++++++++++----
>>>    include/gdbstub/user.h |  6 +++++-
>>>    linux-user/main.c      |  2 +-
>>>    linux-user/signal.c    |  5 ++++-
>>>    6 files changed, 25 insertions(+), 8 deletions(-)
>>> diff --git a/gdbstub/internals.h b/gdbstub/internals.h
>>> index 56b7c13b75..a7cc69dab3 100644
>>> --- a/gdbstub/internals.h
>>> +++ b/gdbstub/internals.h
>>> @@ -58,6 +58,9 @@ typedef struct GDBState {
>>>        int line_csum; /* checksum at the end of the packet */
>>>        GByteArray *last_packet;
>>>        int signal;
>>> +#ifdef CONFIG_USER_ONLY
>>> +    uint8_t siginfo[MAX_SIGINFO_LENGTH];
>>> +#endif
>>
>> If we this in GDBUserState in user.c -- no need for ifdefs then.
> 
> Although it does break on FreeBSD's user target:
> 
>    FAILED: libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o
>    cc -m64 -mcx16 -Ilibqemu-arm-bsd-user.fa.p -I. -I.. -Itarget/arm -I../target/arm -I../common-user/host/x86_64 -I../bsd-user/include -Ibsd-user/freebsd -I../bsd-user/freebsd -I../bsd-user/host/x86_64 -Ibsd-user -I../bsd-user -I../bsd-user/arm -Iqapi -Itrace -Iui -Iui/shader -I/usr/local/include/capstone -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -fstack-protector-strong -Wempty-body -Wendif-labels -Wexpansion-to-defined -Wformat-security -Wformat-y2k -Wignored-qualifiers -Winit-self -Wmissing-format-attribute -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wredundant-decls -Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings -Wno-gnu-variable-sized-type-not-at-end -Wno-initializer-overrides -Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value -Wno-string-plus-int -Wno-tautological-type-limit-compare -Wno-typedef-redefinition -Wthread-safety -iquote . -iquote /tmp/cirrus-ci-build -iquote /tmp/cirrus-ci-build/include -iquote /tmp/cirrus-ci-build/host/include/x86_64 -iquote /tmp/cirrus-ci-build/host/include/generic -iquote /tmp/cirrus-ci-build/tcg/i386 -pthread -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero -fPIE -DNEED_CPU_H '-DCONFIG_TARGET="arm-bsd-user-config-target.h"' '-DCONFIG_DEVICES="arm-bsd-user-config-devices.h"' -MD -MQ libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -MF libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o.d -o libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -c ../gdbstub/user-target.c
>    In file included from ../gdbstub/user-target.c:18:
>    ../gdbstub/internals.h:62:21: error: use of undeclared identifier 'MAX_SIGINFO_LENGTH'
>       62 |     uint8_t siginfo[MAX_SIGINFO_LENGTH];
>          |                     ^
>    1 error generated.
>    [2084/6731] Compiling C object libqemu-arm
> 
> See: https://gitlab.com/stsquad/qemu/-/jobs/6345829419

argh, I've tested all targets for linux-user, but missed bsd-user. I've tried
once to build it but that requires a BSD-like host, which I don't have at the
moment, then I forgot about it... Let me setup one and review the change in
the light of the comments from you and Richard.

Thanks!


Cheers,
Gustavo
Alex Bennée March 8, 2024, 7:25 p.m. UTC | #4
Gustavo Romero <gustavo.romero@linaro.org> writes:

> Hi Alex,
>
> On 3/7/24 7:33 PM, Alex Bennée wrote:
>> Richard Henderson <richard.henderson@linaro.org> writes:
>> 
>>> On 3/7/24 08:26, Gustavo Romero wrote:
>>>> Save target's siginfo into gdbserver_state so it can be used later, for
>>>> example, in any stub that requires the target's si_signo and si_code.
>>>> This change affects only linux-user mode.
>>>> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
>>>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
>>>> ---
>>>>    gdbstub/internals.h    |  3 +++
>>>>    gdbstub/user-target.c  |  3 ++-
>>>>    gdbstub/user.c         | 14 ++++++++++----
>>>>    include/gdbstub/user.h |  6 +++++-
>>>>    linux-user/main.c      |  2 +-
>>>>    linux-user/signal.c    |  5 ++++-
>>>>    6 files changed, 25 insertions(+), 8 deletions(-)
>>>> diff --git a/gdbstub/internals.h b/gdbstub/internals.h
>>>> index 56b7c13b75..a7cc69dab3 100644
>>>> --- a/gdbstub/internals.h
>>>> +++ b/gdbstub/internals.h
>>>> @@ -58,6 +58,9 @@ typedef struct GDBState {
>>>>        int line_csum; /* checksum at the end of the packet */
>>>>        GByteArray *last_packet;
>>>>        int signal;
>>>> +#ifdef CONFIG_USER_ONLY
>>>> +    uint8_t siginfo[MAX_SIGINFO_LENGTH];
>>>> +#endif
>>>
>>> If we this in GDBUserState in user.c -- no need for ifdefs then.
>> Although it does break on FreeBSD's user target:
>>    FAILED: libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o
>>    cc -m64 -mcx16 -Ilibqemu-arm-bsd-user.fa.p -I. -I.. -Itarget/arm -I../target/arm -I../common-user/host/x86_64 -I../bsd-user/include -Ibsd-user/freebsd -I../bsd-user/freebsd -I../bsd-user/host/x86_64 -Ibsd-user -I../bsd-user -I../bsd-user/arm -Iqapi -Itrace -Iui -Iui/shader -I/usr/local/include/capstone -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/usr/local/include -fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -fstack-protector-strong -Wempty-body -Wendif-labels -Wexpansion-to-defined -Wformat-security -Wformat-y2k -Wignored-qualifiers -Winit-self -Wmissing-format-attribute -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wredundant-decls -Wstrict-prototypes -Wtype-limits -Wundef -Wvla -Wwrite-strings -Wno-gnu-variable-sized-type-not-at-end -Wno-initializer-overrides -Wno-missing-include-dirs -Wno-psabi -Wno-shift-negative-value -Wno-string-plus-int -Wno-tautological-type-limit-compare -Wno-typedef-redefinition -Wthread-safety -iquote . -iquote /tmp/cirrus-ci-build -iquote /tmp/cirrus-ci-build/include -iquote /tmp/cirrus-ci-build/host/include/x86_64 -iquote /tmp/cirrus-ci-build/host/include/generic -iquote /tmp/cirrus-ci-build/tcg/i386 -pthread -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -fno-strict-aliasing -fno-common -fwrapv -ftrivial-auto-var-init=zero -fPIE -DNEED_CPU_H '-DCONFIG_TARGET="arm-bsd-user-config-target.h"' '-DCONFIG_DEVICES="arm-bsd-user-config-devices.h"' -MD -MQ libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -MF libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o.d -o libqemu-arm-bsd-user.fa.p/gdbstub_user-target.c.o -c ../gdbstub/user-target.c
>>    In file included from ../gdbstub/user-target.c:18:
>>    ../gdbstub/internals.h:62:21: error: use of undeclared identifier 'MAX_SIGINFO_LENGTH'
>>       62 |     uint8_t siginfo[MAX_SIGINFO_LENGTH];
>>          |                     ^
>>    1 error generated.
>>    [2084/6731] Compiling C object libqemu-arm
>> See: https://gitlab.com/stsquad/qemu/-/jobs/6345829419
>
> argh, I've tested all targets for linux-user, but missed bsd-user. I've tried
> once to build it but that requires a BSD-like host, which I don't have at the
> moment, then I forgot about it... Let me setup one and review the change in
> the light of the comments from you and Richard.

  make vm-build-[open|net|free]bsd

see make vm-help for details.

>
> Thanks!
>
>
> Cheers,
> Gustavo
Gustavo Romero March 8, 2024, 8:24 p.m. UTC | #5
Hi Richard,

On 3/7/24 6:09 PM, Richard Henderson wrote:
> On 3/7/24 08:26, Gustavo Romero wrote:
>> Save target's siginfo into gdbserver_state so it can be used later, for
>> example, in any stub that requires the target's si_signo and si_code.
>>
>> This change affects only linux-user mode.
>>
>> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
>> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   gdbstub/internals.h    |  3 +++
>>   gdbstub/user-target.c  |  3 ++-
>>   gdbstub/user.c         | 14 ++++++++++----
>>   include/gdbstub/user.h |  6 +++++-
>>   linux-user/main.c      |  2 +-
>>   linux-user/signal.c    |  5 ++++-
>>   6 files changed, 25 insertions(+), 8 deletions(-)
>>
>> diff --git a/gdbstub/internals.h b/gdbstub/internals.h
>> index 56b7c13b75..a7cc69dab3 100644
>> --- a/gdbstub/internals.h
>> +++ b/gdbstub/internals.h
>> @@ -58,6 +58,9 @@ typedef struct GDBState {
>>       int line_csum; /* checksum at the end of the packet */
>>       GByteArray *last_packet;
>>       int signal;
>> +#ifdef CONFIG_USER_ONLY
>> +    uint8_t siginfo[MAX_SIGINFO_LENGTH];
>> +#endif
> 
> If we this in GDBUserState in user.c -- no need for ifdefs then.

Thanks, I've moved it to user.c.


>> --- a/gdbstub/user-target.c
>> +++ b/gdbstub/user-target.c
>> @@ -10,11 +10,12 @@
>>   #include "qemu/osdep.h"
>>   #include "exec/gdbstub.h"
>>   #include "qemu.h"
>> -#include "internals.h"
>>   #ifdef CONFIG_LINUX
>>   #include "linux-user/loader.h"
>>   #include "linux-user/qemu.h"
>> +#include "gdbstub/user.h"
>>   #endif
>> +#include "internals.h"
>>   /*
>>    * Map target signal numbers to GDB protocol signal numbers and vice
> 
> Why are any changes required here?
> Perhaps this is improper patch split from one of the others?

This was intentional. Because I declared siginfo[MAX_SIGINFO_LENGTH] in
GDBState struct, which is in internals.h and MAX_SIGINFO_LENGTH is defined
in gdbstub/user.h I had to move internals.h after user.h was included so
MAX_SIGINFO_LENGTH could be found.

I'm reverting it.


>> @@ -140,6 +141,11 @@ int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
>>           return sig;
>>       }
>> +    if (siginfo) {
>> +        /* Save target-specific siginfo. */
>> +        memcpy(gdbserver_state.siginfo, siginfo, siginfo_len);
>> +    }
> 
> A comment here about asserting the size at compile-time elsewhere would be welcome for future code browsers.

Done.


> Need to record siginfo_len for later use -- you don't want to expose all 128 bytes if the actual structure is smaller.

In the stub, the full size is only used to check if the requested offset+len is valid.
So the only size that matters for reading data from siginfo and assembling
the reply is the length in the query, not siginfo_len. But I agree it's better, even
more now that I moved the stub from user-target.c to user.c.


>> @@ -510,7 +516,7 @@ void gdb_breakpoint_remove_all(CPUState *cs)
>>   void gdb_syscall_handling(const char *syscall_packet)
>>   {
>>       gdb_put_packet(syscall_packet);
>> -    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL);
>> +    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL, NULL, 0);
>>   }
>>   static bool should_catch_syscall(int num)
>> @@ -528,7 +534,7 @@ void gdb_syscall_entry(CPUState *cs, int num)
>>   {
>>       if (should_catch_syscall(num)) {
>>           g_autofree char *reason = g_strdup_printf("syscall_entry:%x;", num);
>> -        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
>> +        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
>>       }
>>   }
>> @@ -536,7 +542,7 @@ void gdb_syscall_return(CPUState *cs, int num)
>>   {
>>       if (should_catch_syscall(num)) {
>>           g_autofree char *reason = g_strdup_printf("syscall_return:%x;", num);
>> -        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
>> +        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
>>       }
> 
> All of this makes me wonder if we should provide a different interface for syscalls, even if it uses the same code paths internally.

Should I address it in this series? I'm sure how that interface would be.


> Do we want to zero the gdbserver siginfo to indicate that the contents are no longer valid?  I know it's not a real signal delivered to the process, but might we need to construct a simple siginfo struct to match the sigtrap?

In gdb_handlesig we always copy the full size of siginfo to gdbserver_user_state siginfo,
which is passed in siginfo_len and now recorded gdbserver siginfo_len too for later use.
Isn't that copy guaranteeing that gdbserver siginfo has always no stale data?


Cheers,
Gustavo
Richard Henderson March 9, 2024, 12:41 a.m. UTC | #6
On 3/8/24 09:25, Alex Bennée wrote:
>    make vm-build-[open|net|free]bsd
> 
> see make vm-help for details.

That won't build freebsd user.
Something I've mentioned to you before...


r~
Alex Bennée March 9, 2024, 11:43 a.m. UTC | #7
Richard Henderson <richard.henderson@linaro.org> writes:

> On 3/8/24 09:25, Alex Bennée wrote:
>>    make vm-build-[open|net|free]bsd
>> see make vm-help for details.
>
> That won't build freebsd user.
> Something I've mentioned to you before...

  make vm-build-freebsd BUILD_TARGET=all

I guess the default "check" target doesn't work due to the missing cross
compilers meaning we have no check-tcg target in the default check list.

>
>
> r~
diff mbox series

Patch

diff --git a/gdbstub/internals.h b/gdbstub/internals.h
index 56b7c13b75..a7cc69dab3 100644
--- a/gdbstub/internals.h
+++ b/gdbstub/internals.h
@@ -58,6 +58,9 @@  typedef struct GDBState {
     int line_csum; /* checksum at the end of the packet */
     GByteArray *last_packet;
     int signal;
+#ifdef CONFIG_USER_ONLY
+    uint8_t siginfo[MAX_SIGINFO_LENGTH];
+#endif
     bool multiprocess;
     GDBProcess *processes;
     int process_num;
diff --git a/gdbstub/user-target.c b/gdbstub/user-target.c
index b7d4c37cd8..215bf33ab3 100644
--- a/gdbstub/user-target.c
+++ b/gdbstub/user-target.c
@@ -10,11 +10,12 @@ 
 #include "qemu/osdep.h"
 #include "exec/gdbstub.h"
 #include "qemu.h"
-#include "internals.h"
 #ifdef CONFIG_LINUX
 #include "linux-user/loader.h"
 #include "linux-user/qemu.h"
+#include "gdbstub/user.h"
 #endif
+#include "internals.h"
 
 /*
  * Map target signal numbers to GDB protocol signal numbers and vice
diff --git a/gdbstub/user.c b/gdbstub/user.c
index a157e67f95..777fa78ef4 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -131,7 +131,8 @@  void gdb_qemu_exit(int code)
     exit(code);
 }
 
-int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
+int gdb_handlesig(CPUState *cpu, int sig, const char *reason, void *siginfo,
+                  int siginfo_len)
 {
     char buf[256];
     int n;
@@ -140,6 +141,11 @@  int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
         return sig;
     }
 
+    if (siginfo) {
+        /* Save target-specific siginfo. */
+        memcpy(gdbserver_state.siginfo, siginfo, siginfo_len);
+    }
+
     /* disable single step if it was enabled */
     cpu_single_step(cpu, 0);
     tb_flush(cpu);
@@ -510,7 +516,7 @@  void gdb_breakpoint_remove_all(CPUState *cs)
 void gdb_syscall_handling(const char *syscall_packet)
 {
     gdb_put_packet(syscall_packet);
-    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL);
+    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL, NULL, 0);
 }
 
 static bool should_catch_syscall(int num)
@@ -528,7 +534,7 @@  void gdb_syscall_entry(CPUState *cs, int num)
 {
     if (should_catch_syscall(num)) {
         g_autofree char *reason = g_strdup_printf("syscall_entry:%x;", num);
-        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
+        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
     }
 }
 
@@ -536,7 +542,7 @@  void gdb_syscall_return(CPUState *cs, int num)
 {
     if (should_catch_syscall(num)) {
         g_autofree char *reason = g_strdup_printf("syscall_return:%x;", num);
-        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
+        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
     }
 }
 
diff --git a/include/gdbstub/user.h b/include/gdbstub/user.h
index 6647af2123..0ec9a7e596 100644
--- a/include/gdbstub/user.h
+++ b/include/gdbstub/user.h
@@ -9,11 +9,15 @@ 
 #ifndef GDBSTUB_USER_H
 #define GDBSTUB_USER_H
 
+#define MAX_SIGINFO_LENGTH 128
+
 /**
  * gdb_handlesig() - yield control to gdb
  * @cpu: CPU
  * @sig: if non-zero, the signal number which caused us to stop
  * @reason: stop reason for stop reply packet or NULL
+ * @siginfo: target-specific siginfo struct
+ * @siginfo_len: target-specific siginfo struct length
  *
  * This function yields control to gdb, when a user-mode-only target
  * needs to stop execution. If @sig is non-zero, then we will send a
@@ -25,7 +29,7 @@ 
  * or 0 if no signal should be delivered, ie the signal that caused
  * us to stop should be ignored.
  */
-int gdb_handlesig(CPUState *, int, const char *);
+int gdb_handlesig(CPUState *, int, const char *, void *, int);
 
 /**
  * gdb_signalled() - inform remote gdb of sig exit
diff --git a/linux-user/main.c b/linux-user/main.c
index 049fd85a2a..3187be48d6 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1014,7 +1014,7 @@  int main(int argc, char **argv, char **envp)
                     gdbstub);
             exit(EXIT_FAILURE);
         }
-        gdb_handlesig(cpu, 0, NULL);
+        gdb_handlesig(cpu, 0, NULL, NULL, 0);
     }
 
 #ifdef CONFIG_SEMIHOSTING
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 7a4c8e416e..98d1eacffe 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -34,6 +34,9 @@ 
 #include "user/safe-syscall.h"
 #include "tcg/tcg.h"
 
+/* target_siginfo_t must fit in gdbstub's siginfo save area. */
+QEMU_BUILD_BUG_ON(sizeof(target_siginfo_t) > MAX_SIGINFO_LENGTH);
+
 static struct target_sigaction sigact_table[TARGET_NSIG];
 
 static void host_signal_handler(int host_signum, siginfo_t *info,
@@ -1186,7 +1189,7 @@  static void handle_pending_signal(CPUArchState *cpu_env, int sig,
      */
     tswap_siginfo(&k->info, &k->info);
 
-    sig = gdb_handlesig(cpu, sig, NULL);
+    sig = gdb_handlesig(cpu, sig, NULL, &k->info, sizeof(k->info));
     if (!sig) {
         sa = NULL;
         handler = TARGET_SIG_IGN;