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linux-user/hppa: Document non-use of setup_sigtramp 

We cannot use a raw sigtramp page for hppa,
but must wait for full vdso support.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210929130553.121567-10-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Richard Henderson 2021-09-29 09:05:36 -04:00 committed by Laurent Vivier
parent c8ef02b1ac
commit a22fccd8b7
1 changed files with 14 additions and 0 deletions
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14
linux-user/hppa/target_signal.h
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@ -71,4 +71,18 @@ typedef struct target_sigaltstack {
/* mask for all SS_xxx flags */
#define TARGET_SS_FLAG_BITS TARGET_SS_AUTODISARM
/*
* We cannot use a bare sigtramp page for hppa-linux.
*
* Unlike other guests where we use the instructions at PC to validate
* an offset from SP, the hppa libgcc signal frame fallback unwinding uses
* the PC address itself to find the frame. This is due to the fact that
* the hppa grows the stack upward, and the frame is of unknown size.
*
* TODO: We should be able to use a VDSO to address this, by providing
* proper unwind info for the sigtramp code, at which point the fallback
* unwinder will not be used.
*/
#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
#endif /* HPPA_TARGET_SIGNAL_H */