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feat(trbe): introduce trbe_disable() function

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This patch adds trbe_disable() which disables Trace buffer access
from lower ELs in all security state. This function makes Secure
state the owner of Trace buffer and access from EL2/EL1 generate
trap exceptions to EL3.

Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: If3e3bd621684b3c28f44c3ed2fe3df30b143f8cd
This commit is contained in:
Arvind Ram Prakash 2024-07-19 11:39:49 -05:00 • committed by Manish Pandey
parent 651fe5073c
commit b36e975ea3
2 changed files with 23 additions and 0 deletions
include/lib/extensions
trbe.h
lib/extensions/trbe
trbe.c

4
include/lib/extensions/trbe.h
View file

@ -10,9 +10,13 @@
#include <context.h>
#if ENABLE_TRBE_FOR_NS
void trbe_disable(cpu_context_t *ctx);
void trbe_enable(cpu_context_t *ctx);
void trbe_init_el2_unused(void);
#else
static inline void trbe_disable(cpu_context_t *ctx)
{
}
static inline void trbe_enable(cpu_context_t *ctx)
{
}

19
lib/extensions/trbe/trbe.c
View file

@ -39,6 +39,25 @@ void trbe_enable(cpu_context_t *ctx)
write_ctx_reg(state, CTX_MDCR_EL3, mdcr_el3_val);
}
void trbe_disable(cpu_context_t *ctx)
{
el3_state_t *state = get_el3state_ctx(ctx);
u_register_t mdcr_el3_val = read_ctx_reg(state, CTX_MDCR_EL3);
/*
* MDCR_EL3.NSTBE = 0b0
* Trace Buffer owning Security state is secure state. If FEAT_RME
* is not implemented, this field is RES0.
*
* MDCR_EL3.NSTB = 0b00
* Clear these bits to disable access of trace buffer control registers
* from lower ELs in any security state.
*/
mdcr_el3_val &= ~(MDCR_NSTB(MDCR_NSTB_EL1));
mdcr_el3_val &= ~(MDCR_NSTBE_BIT);
write_ctx_reg(state, CTX_MDCR_EL3, mdcr_el3_val);
}
void trbe_init_el2_unused(void)
{
/*