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target/i386: Implement x86_cpu_record_sigsegv

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Record cr2, error_code, and exception_index.  That last means
that we must exit to cpu_loop ourselves, instead of letting
exception_index being overwritten.

Use the maperr parameter to properly set PG_ERROR_P_MASK.

Reviewed by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-09-17 19:10:25 -07:00
parent 860e0b965b
commit f74bd157c6
3 changed files with 25 additions and 7 deletions
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6
target/i386/tcg/helper-tcg.h
View File

@ -43,9 +43,15 @@ bool x86_cpu_exec_interrupt(CPUState *cpu, int int_req);
#endif
/* helper.c */
#ifdef CONFIG_USER_ONLY
void x86_cpu_record_sigsegv(CPUState *cs, vaddr addr,
MMUAccessType access_type,
bool maperr, uintptr_t ra);
#else
bool x86_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
MMUAccessType access_type, int mmu_idx,
bool probe, uintptr_t retaddr);
#endif
void breakpoint_handler(CPUState *cs);

3
target/i386/tcg/tcg-cpu.c
View File

@ -72,10 +72,11 @@ static const struct TCGCPUOps x86_tcg_ops = {
.synchronize_from_tb = x86_cpu_synchronize_from_tb,
.cpu_exec_enter = x86_cpu_exec_enter,
.cpu_exec_exit = x86_cpu_exec_exit,
.tlb_fill = x86_cpu_tlb_fill,
#ifdef CONFIG_USER_ONLY
.fake_user_interrupt = x86_cpu_do_interrupt,
.record_sigsegv = x86_cpu_record_sigsegv,
#else
.tlb_fill = x86_cpu_tlb_fill,
.do_interrupt = x86_cpu_do_interrupt,
.cpu_exec_interrupt = x86_cpu_exec_interrupt,
.debug_excp_handler = breakpoint_handler,

23
target/i386/tcg/user/excp_helper.c
View File

@ -22,18 +22,29 @@
#include "exec/exec-all.h"
#include "tcg/helper-tcg.h"
bool x86_cpu_tlb_fill(CPUState *cs, vaddr addr, int size,
MMUAccessType access_type, int mmu_idx,
bool probe, uintptr_t retaddr)
void x86_cpu_record_sigsegv(CPUState *cs, vaddr addr,
MMUAccessType access_type,
bool maperr, uintptr_t ra)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
/*
* The error_code that hw reports as part of the exception frame
* is copied to linux sigcontext.err. The exception_index is
* copied to linux sigcontext.trapno. Short of inventing a new
* place to store the trapno, we cannot let our caller raise the
* signal and set exception_index to EXCP_INTERRUPT.
*/
env->cr[2] = addr;
env->error_code = (access_type == MMU_DATA_STORE) << PG_ERROR_W_BIT;
env->error_code |= PG_ERROR_U_MASK;
env->error_code = ((access_type == MMU_DATA_STORE) << PG_ERROR_W_BIT)
| (maperr ? 0 : PG_ERROR_P_MASK)
| PG_ERROR_U_MASK;
cs->exception_index = EXCP0E_PAGE;
/* Disable do_interrupt_user. */
env->exception_is_int = 0;
env->exception_next_eip = -1;
cpu_loop_exit_restore(cs, retaddr);
cpu_loop_exit_restore(cs, ra);
}